Antithrombin III for critically ill patients

Mikkel Allingstrup; Jørn Wetterslev; Frederikke B Ravn; Ann Merete Møller; Arash Afshari

doi:10.1002/14651858.CD005370.pub3

. 2016 Feb 9;2016(2):CD005370. doi: 10.1002/14651858.CD005370.pub3

Antithrombin III for critically ill patients

Mikkel Allingstrup ^1,^2,^✉, Jørn Wetterslev ³, Frederikke B Ravn ⁴, Ann Merete Møller ⁵, Arash Afshari ¹

Editor: Cochrane Emergency and Critical Care Group

PMCID: PMC6517014 PMID: 26858174

Abstract

Background

Critical illness is associated with uncontrolled inflammation and vascular damage which can result in multiple organ failure and death. Antithrombin III (AT III) is an anticoagulant with anti‐inflammatory properties but the efficacy and any harmful effects of AT III supplementation in critically ill patients are unknown. This review was published in 2008 and updated in 2015.

Objectives

To examine:

1. The effect of AT III on mortality in critically ill participants.

2. The benefits and harms of AT III.

We investigated complications specific and not specific to the trial intervention, bleeding events, the effect on sepsis and disseminated intravascular coagulation (DIC) and the length of stay in the intensive care unit (ICU) and in hospital in general.

Search methods

We searched the following databases from inception to 27 August 2015: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid SP), EMBASE (Ovid SP,), CAB, BIOSIS and CINAHL. We contacted the main authors of trials to ask for any missed, unreported or ongoing trials.

Selection criteria

Data collection and analysis

Our primary outcome measure was mortality. Two authors each independently abstracted data and resolved any disagreements by discussion. We presented pooled estimates of the intervention effects on dichotomous outcomes as risk ratios (RR) with 95% confidence intervals (CI). We performed subgroup analyses to assess risk of bias, the effect of AT III in different populations (sepsis, trauma, obstetrics, and paediatrics), and the effect of AT III in patients with or without the use of concomitant heparin. We assessed the adequacy of the available number of participants and performed trial sequential analysis (TSA) to establish the implications for further research.

Main results

We included 30 RCTs with a total of 3933 participants (3882 in the primary outcome analyses).

Combining all trials, regardless of bias, showed no statistically significant effect of AT III on mortality with a RR of 0.95 (95% CI 0.88 to 1.03), I² statistic = 0%, fixed‐effect model, 29 trials, 3882 participants, moderate quality of evidence). For trials with low risk of bias the RR was 0.96 (95% Cl 0.88 to 1.04, I² statistic = 0%, fixed‐effect model, 9 trials, 2915 participants) and for high risk of bias RR 0.94 (95% Cl 0.77 to 1.14, I² statistic = 0%, fixed‐effect model, 20 trials, 967 participants).

For participants with severe sepsis and DIC the RR for mortality was non‐significant, 0.95 (95% Cl 0.88 to 1.03, I² statistic = 0%, fixed‐effect model, 12 trials, 2858 participants, moderate quality of evidence).

We conducted 14 subgroup and sensitivity analyses with respect to the different domains of risk of bias, but detected no statistically significant benefit in any subgroup analyses.

Our secondary objective was to assess the benefits and harms of AT III. For complications specific to the trial intervention the RR was 1.26 (95% Cl 0.83 to 1.92, I² statistic = 0%, random‐effect model, 3 trials, 2454 participants, very low quality of evidence). For complications not specific to the trial intervention, the RR was 0.71 (95% Cl 0.08 to 6.11, I² statistic = 28%, random‐effects model, 2 trials, 65 participants, very low quality of evidence). For complications other than bleeding, the RR was 0.72 ( 95% Cl 0.42 to 1.25, I² statistic = 0%, fixed‐effect model, 3 trials, 187 participants, very low quality of evidence). Eleven trials investigated bleeding events and we found a statistically significant increase, RR 1.58 (95% CI 1.35 to 1.84, I² statistic = 0%, fixed‐effect model, 11 trials, 3019 participants, moderate quality of evidence) in the AT III group. The amount of red blood cells administered had a mean difference (MD) of 138.49 (95% Cl ‐391.35 to 668.34, I² statistic = 84%, random‐effect model, 4 trials, 137 participants, very low quality of evidence). The effect of AT III in patients with multiple organ failure (MOF) was a MD of ‐1.24 (95% Cl ‐2.18 to ‐0.29, I² statistic = 48%, random‐effects model, 3 trials, 156 participants, very low quality of evidence) and for patients with an Acute Physiology and Chronic Health Evaluation score (APACHE) at II and III the MD was ‐2.18 (95% Cl ‐4.36 to ‐0.00, I² statistic = 0%, fixed‐effect model, 3 trials, 102 participants, very low quality of evidence). The incidence of respiratory failure had a RR of 0.93 (95% Cl 0.76 to 1.14, I² statistic = 32%, random‐effects model, 6 trials, 2591 participants, moderate quality of evidence). AT III had no statistically significant impact on the duration of mechanical ventilation (MD 2.20 days, 95% Cl ‐1.21 to 5.60, I² statistic = 0%, fixed‐effect model, 3 trials, 190 participants, very low quality of evidence); on the length of stay in the ICU (MD 0.24, 95% Cl ‐1.34 to 1.83, I² statistic = 0%, fixed‐effect model, 7 trials, 376 participants, very low quality of evidence) or on the length of stay in hospital in general (MD 1.10, 95% Cl ‐7.16 to 9.36), I² statistic = 74%, 4 trials, 202 participants, very low quality of evidence).

Authors' conclusions

There is insufficient evidence to support AT III substitution in any category of critically ill participants including the subset of patients with sepsis and DIC. We did not find a statistically significant effect of AT III on mortality, but AT III increased the risk of bleeding events. Subgroup analyses performed according to duration of intervention, length of follow‐up, different patient groups, and use of adjuvant heparin did not show differences in the estimates of intervention effects. The majority of included trials were at high risk of bias (GRADE; very low quality of evidence for most of the analyses). Hence a large RCT of AT III is needed, without adjuvant heparin among critically ill patients such as those with severe sepsis and DIC, with prespecified inclusion criteria and good bias protection.

Plain language summary

Antithrombin III for critically ill patients

Background

Antithrombin is a small particle produced by the liver. It deactivates several substances which affect the ability of the blood to form clots. Its activity is increased many‐fold by the drug heparin, which enhances the binding of antithrombin to clotting factors so that the blood does not form clots. Antithrombin also reduces inflammation in the human body. Inflammation is the body's attempt at self protection to remove harmful stimuli and begin healing processes. Inflammation is thus not always a bad process.

This updated review assessed the effects of antithrombin in people recovering from critical illness. Our primary goal was to investigate whether the number of people who died changed by giving antithrombin. We also investigated whether there were more complications among people treated with this drug, the extent of bleeding and the amount of blood given to the critical ill people. Finally we examined the impact of antithrombin on the duration of respiratory therapy, length of stay in the intensive care units and in the hospital in general.

Study characteristics

We included 30 trials with 3933 participants (3882 in our data calculation) in this updated review. We found the overall quality of trials to be poor, with little information on how the experiments were carried out. The results were limited and the included trials were mostly small. In most trials, there was a high risk of misleading information. Thus, the results must be interpreted with caution. The evidence is up to date to 27 August 2015.

Study funding sources

Three of the 30 included trials reported receiving money from drug companies.

Key results

In our review we could not identify a clear advantage of antithrombin for the objectives we examined, overall or among various types of patients or subgroups. In our investigation of bleeding events, however, we found an increased risk of bleeding for patients treated with antithrombin.

Quality of the evidence

Overall, there was a low quality of information from the studies regarding all of the results. We conclude that there is a need for a large‐scale clinical trial with low risk of misleading information to investigate the advantages and harms of this drug among critically ill patients.

Summary of findings

Trial sequential analysis of AT III vs placebo or no intervention on number of bleeding events. The Diversity (D‐square) is 0%, the control event proportion is 13.2% and the required information size is estimated for an anticipated relative risk increase of 20% with a type 1 and 2 error risk of 5% and 20% respectively. The cumulative Z‐curve is breaking through the trial sequential monitoring boundary for harm suggesting, even though the required information size has not been reached, that AT III increases the number of bleeding events. The TSA‐adjusted meta‐analysis yields a RR of 1.85 (95% CI 1.35 to 1.85).

Background

Description of the condition

Despite advances in the medical field, growing numbers of patients are becoming critically ill. Each year, 5,700,000 people in the USA are admitted to intensive care units (ICUs) (Wunsch 2008).

Critical illness is characterized by cellular immune dysfunction, vascular damage and uncontrolled hyperinflammation, even when the cause of illness is not infection. In critical illness, a systemic activation of coagulation may occur which, at its worst, results in a fulminant disseminated intravascular coagulation (DIC). DIC is characterized by simultaneous widespread microvascular thrombosis and profuse bleeding from various sites (Levi 2004). Sepsis resulting from a generalized inflammatory and procoagulant response to an infection is associated with a high risk of mortality. Twenty per cent of patients who develop severe sepsis will die during their hospitalization (Mayr 2014). Septic shock is associated with the highest mortality, approaching 50% (Mayr 2014). This rate increases in the presence of circulatory shock despite aggressive antimicrobial therapy, adequate fluid resuscitation, and optimal care (Periti 2000), and may reach as high as 70% in patients with multiple organ dysfunction (Polderman 2004).

The inflammation associated with critical illness is characterized by an increase in the number and activity of numerous molecules, such as platelet activating factor, von Willebrand factor, and tumour necrosis factor. There is a simultaneous increase in the activity of pro‐inflammatory and pro‐coagulant processes, such as thrombin formation, fibrin deposition at the vascular wall, and the formation of aggregates containing platelets and leukocytes. Leukocyte rolling, adhesion, and transmigration are also important parts of the inflammatory reaction. These processes lead to capillary leakage, severe disturbance of the microcirculation, tissue damage, and eventually multiorgan failure and death (Becker 2000).

Description of the intervention

Any proposed treatment of critical illness should aim to eliminate the underlying disorder or condition and to restore microvascular function, hence reducing organ dysfunction (Levi 2004).

Antithrombin III (AT III) is primarily a potent anticoagulant with independent anti‐inflammatory properties. AT III irreversibly inhibits serine proteases (for example, activated factor X and thrombin) in a one‐to‐one ratio, with the generation of protease‐AT III complexes. Heparin prevents AT III from interacting with the endothelial cell surface by binding to sites on the AT III molecule, competing for the AT III binding site, and reducing AT III ability to interact with its cellular receptor. AT III's anticoagulant effect is thus greatly accelerated (by a factor of 1000) by heparin; heparin reduces AT III's anti‐inflammatory properties, weakens vascular protection, and increases bleeding events (Diaz 2015; Opal 2002; Rublee 2003).

Heparin in patients with sepsis, septic shock, or DIC associated with infection may be associated with decreased mortality (Zarychanski 2015). However, the overall effect is still not clear. Major bleeding events related to heparin administration cannot be excluded (Zarychanski 2015) and safety outcomes have yet to be validated in a multicentre trial setting.

How the intervention might work

The blood concentration of AT III falls by 20% to 40% in septic patients, and these levels correlate with disease severity and clinical outcome (Opal 2002; Wiedermann 2002). This reduction in concentration is due to the combined effect of decreased production of AT III in the liver, inactivation by the enzyme elastase, which is increased during inflammation, and loss of AT III from the circulation into tissues through inflamed and leaking capillary blood vessels. These processes reduce the half‐life of AT III from a mean of 55 hours to 20 hours (Fourrier 2000). The main mechanism of AT III depletion in severe sepsis is linked to consumption of the molecule.

It is this depletion of AT III that has prompted research into the potential benefits of replenishing AT III levels. Investigators have often tried to increase the antithrombin concentration to supranormal values because the activity of pro‐inflammatory and pro‐coagulant molecules are increased in critically ill patients. Thus artificially high levels of AT III may be required to overcome the inhibitory effect of thrombin and other such serine proteases. This is because the normal serum concentration of AT III does not necessarily reflect the amount bound to endothelial receptors and appears insufficient (Fourrier 2000). Finally, by blocking the actions of thrombin, AT III may have anti‐angiogenic and antitumour properties (Larsson 2001).

Why it is important to do this review

Although critically ill patients are a heterogeneous population, they are characterized by having systemic inflammation, no matter what the cause of their illness. This inflammation causes further damage to tissues and organs and can result in multiple organ failure and death. The process of inflammation can be modified by AT III, whether or not clotting is abnormal, and it is possible that AT III can reduce the high death rate or permanent damage experienced by critically ill patients. The benefit of AT III supplementation in critically ill patients is still controversial and its efficacy is still debated (Tagami 2014; Tagami 2015).

Objectives

To examine:

The effect of AT III on mortality in critically ill participants.
The benefits and harms of AT III.

We investigated complications specific and not specific to the trial intervention, bleeding events, the effect on sepsis and DIC and the length of stay in ICU and in hospital in general.

Methods

Criteria for considering studies for this review

Types of studies

We included randomized controlled trials (RCTs) irrespective of publication status, date of publication, blinding status, outcomes published, or language. We contacted the investigators and the authors in order to retrieve relevant data. We included unpublished trials only if trial data and methodological descriptions were either provided in written form or could be retrieved from the trial authors. We excluded cross‐over trials. We include In this updated review trials published as abstracts (Balk 1995; Blauhut 1985; Muntean 1989; Palareti 1995; Schuster 1997).

Types of participants

We included critically ill participants as variously defined by the trial authors. However, we excluded trials of adjuvant AT III administration for the reduction of cardiovascular events in the invasive treatment of acute myocardial infarction.

The terminology for sepsis, as originally proposed by the American College of Chest Physicians and the Society of Critical Care Medicine, is in many ways outdated (Opal 2003). A loose definition of sepsis can easily result in enrolment of a heterogeneous population and hence in exaggerated findings, in either direction, that are difficult to reproduce. However, we accepted the various definitions of sepsis, septic shock, DIC, and other critical illnesses as proposed by the authors; we did not exclude any trial based on their definitions. We chose to accept the term 'standard treatment of sepsis and DIC' as reported by many authors, despite the lack of a generally accepted treatment regimen.

We classified two trials as obstetric trials (Kobayashi 2003; Maki 2000); four trials as paediatric trials (Fulia 2003; Mitchell 2003; Muntean 1989; Schmidt 1998); and a further two trials as trauma trials (Grenander 2001; Waydhas 1998).

Types of interventions

We included AT III versus no intervention or placebo. We included any dose of AT III, any duration of administration, and co‐interventions, but excluded trials that compared different doses of AT III.

Types of outcome measures

Primary outcomes

Overall mortality (longest follow‐up, regardless of the period of follow‐up)

Secondary outcomes

Complications during the inpatient stay specific to the trial intervention, e.g. pneumonia, congestive cardiac failure, respiratory failure, myocardial infarction, renal failure, cerebrovascular accident
Complications during the inpatient stay not specific to the trial intervention, e.g. bleeding, limb venous thrombosis, line sepsis, local haematoma
Complications specific to the trial intervention other than bleeding
Bleeding events
Amount of red blood cells administered
Incidence of surgical intervention
Severity of sepsis (according to different organ dysfunction scores; sepsis versus septic shock if adequately defined by authors)
Incidence of respiratory failure not present at admission (mechanically‐assisted ventilation)
Duration of mechanical ventilation
Length of stay in hospital
Mean length of stay in the intensive care unit (ICU)
Overall mortality among patients with severe sepsis and DIC

We defined bleeding events (4) as intracranial bleeding or bleeding requiring transfusion of at least three units of blood. We counted repeated transfusions in the same participant as a singular event.

Search methods for identification of studies

Electronic searches

In this updated review, we have further extended the original review's search from November 2006 (Afshari 2008). Thus, we searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 8). We updated our search of MEDLINE (Ovid SP, to 27 August 2015), EMBASE (Ovid SP, to 27 August 2015) and CINAHL (to 27 August 2015). The search is now from inception until 27 August 2015.

For specific information regarding our search strategies and results, please see Appendix 1.

Searching other resources

We searched for ongoing clinical trials and unpublished trials on the following Internet sites:

We handsearched the reference lists of reviews, randomized and non‐randomized trials, and editorials for additional trials. We contacted the main authors of trials and experts in this field to ask for any missed, unreported, or ongoing studies. We applied no language restrictions to eligible reports. We conducted the latest search on 27 August 2015.

Data collection and analysis

Three review authors (FR, MA and AA) independently screened and classified all citations as potential primary studies, review articles or other. The three review authors also independently examined all potential primary studies and decided on their inclusion in the review. We evaluated all trials for major potential sources of bias (random sequence generation, allocation concealment, blinding, intention‐to‐treat analysis, funding and completeness of follow‐up) (See Figure 2; Figure 3). We assessed each trial quality factor separately and defined the trials as having low risk of bias only if they adequately fulfilled all of the criteria. We independently abstracted and evaluated methodology and outcomes from each trial, in accordance with the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We resolved disagreements by consensus among the review authors.

Selection of studies

We assessed the reports identified from the described searches and excluded obviously irrelevant reports. We screened all articles by title and abstract, and then as full‐text articles for inclusion. We list all excluded studies with reasons for their exclusion in the Characteristics of excluded studies

Two review authors (FR, MA) independently examined the retrieved reports for eligibility. We performed this process without blinding to study authors, institution, journal of publication or results. We resolved disagreements by consensus among the review authors. We provide a detailed description of the search and assessment.

Data extraction and management

We used the above strategy to search for relevant trials. We then screened the titles and abstracts in order to identify studies for eligibility. We independently extracted and collected the data on a standardized paper form. We were not blinded to the study author, source institution, or the publication source of trials. We resolved disagreements by discussion and approached all first authors of the included trials for additional information on risks of bias. For more detailed information please see the section Contributions of authors.

Assessment of risk of bias in included studies

We evaluated the validity and design characteristics of each trial. We evaluated trials for major potential sources of bias (random sequence generation, allocation concealment, blinding, intention‐to‐treat analysis, funding and completeness of follow‐up). We assessed each trial quality factor separately and defined the trials as having a low risk of bias only if they adequately fulfilled all of the criteria.

1. Random sequence generation

Assessment of randomization: sufficiency of the method in producing two comparable groups before intervention.

Grade: ’low risk’: a truly random process (e.g. random computer number generator, coin tossing, throwing dice); ’high risk’: any non‐random process (e.g. date of birth, date of admission by hospital or clinic record number or by availability of the intervention); or ’unclear risk’: insufficient information.

2. Allocation concealment

Allocation method prevented investigators or participants from foreseeing assignment.

Grade: ’low risk’: central allocation or sealed opaque envelopes; ’high risk’: using an open allocation schedule or other unconcealed procedure; or ’unclear risk’: insufficient information.

3. Blinding

Assessment of appropriate blinding of the team of investigators and participants: person responsible for participant care, participants and outcome assessors.

Grade: ’low risk’: blinding considered adequate if participants and personnel were kept unaware of intervention allocations after inclusion of participants into the study, and if the method of blinding involved a placebo indistinguishable from the intervention, as mortality is an objective outcome; ’high risk’: not double‐blinded, categorized as an open‐label study, or without use of a placebo indistinguishable from the intervention; ’unclear risk’: blinding not described.

4. Incomplete outcome data

Completeness of outcome data, including attritions and exclusions.

Grade: ’low risk’: numbers and reasons for dropouts and withdrawals in the intervention groups described, or no dropouts or withdrawals were specified; ’high risk’: no description of dropouts and withdrawals provided; ’unclear risk’: report gave the impression of no dropouts or withdrawals, but this was not specifically stated.

5. Selective reporting

The possibility of selective outcome reporting.

Grade: ’low risk’: reported outcomes prespecified in an available study protocol, or, if this is not available, published report includes all expected outcomes; ’high risk’: not all prespecified outcomes reported, reported using non‐prespecified subscales, reported incompletely or report fails to include a key outcome that would have been expected for such a study; ’unclear risk’: insufficient information.

6. Funding bias

Assessment of any possible funding bias.

Grade: ’low risk’: reported no funding, funding from universities or public institutions; ’high risk’: funding from private investors, pharmaceutical companies or trial investigator employed by the pharmaceutical company; ’unclear risk’: insufficient information.

7. Other bias

Assessment of any possible sources of bias not addressed in domains 1 to 6.

Grade: ’low risk’: report appears to be free of such biases; ’high risk’: at least one important bias is present that is related to study design, early stopping because of some data‐dependent process, extreme baseline imbalance, academic bias, claimed fraudulence or other problems; or ’unclear risk’: insufficient information or evidence that an identified problem will introduce bias.

Measures of treatment effect

We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous data (binary outcomes). These included:

Primary outcomes:

Overall mortality (longest follow‐up, regardless of the period of follow‐up)

Secondary outcomes:

Complications during the inpatient stay specific to the trial intervention
Complications during the inpatient stay not specific to the trial intervention
Complications specific to the trial intervention other than bleeding
Bleeding events
Incidence of surgical intervention
Incidence of respiratory failure not present at admission
Overall mortality among patients with severe sepsis and DIC

We used the mean difference (MD) with a 95% confidence interval (CI), if data were continuous and measured in the same way between trials.

Amount of red blood cells administered
Severity of sepsis
Duration of mechanical ventilation
Length of stay in hospital
Mean length of stay in the ICU

Unit of analysis issues

Studies with multiple intervention groups

In accordance with the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011), for trials with two or more groups receiving different doses, we combined data for the primary and secondary outcomes. We excluded trials that only compared different doses of AT III and did not have a control group, with or without placebo.

Dealing with missing data

We contacted the authors of trials with missing data in order to retrieve the relevant information. For all included studies we noted levels of attrition and any exclusions. In case of missing data, we chose ’complete‐case analysis’ for our primary outcomes, which excludes from the analysis all participants with the outcome missing.

Selective outcome reporting occurs when nonsignificant results are selectively withheld from publication (Chan 2004), and is defined as the selection, on the basis of the results, of a subset of the original variables recorded for inclusion in publication of trials (Hutton 2000). The most important types of selective outcome reporting are: selective omission of outcomes from reports; selective choice of data for an outcome; selective reporting of different analyses using the same data; selective reporting of subsets of the data and selective underreporting of data (Higgins 2011).

Assessment of heterogeneity

We explored heterogeneity using the I² statistic and Chi² test. An I² statistic above 50% represents substantial heterogeneity (Higgins 2011). In case of I² statistic > 0, we tried to determine the cause of heterogeneity by performing relevant subgroup analyses. We used the Chi² test to provide an indication of heterogeneity between studies, with a P value ≤ 0.1 considered significant.

Assessment of reporting biases

Funding bias is related to the possible publication delay or discouragement of undesired results in trials sponsored by the industry (Higgins 2011).

Data synthesis

Data analysis

We used Review Manager 5 software (RevMan 5.3). We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous variables and mean difference (MD) with CI for continuous outcomes. We used the Chi² test to provide an indication of heterogeneity between studies, with a P value < 0.1 considered significant. The degree of heterogeneity observed in the results was quantified using the I² statistic, which can be interpreted as the proportion of the total variation observed between the studies that is attributable to differences between studies rather than to sampling error (Higgins 2002). An I² statistic > 75% is considered as very heterogeneous. We used both a random‐effects model and a fixed‐effect model. If the I² statistic = 0% we only reported the results from the fixed‐effect model, and in the case of I² statistic > 0% we reported only the results from the random‐effects model.

Trial sequential analysis

The risk of type 1 errors in meta‐analyses due to sparse data and repeated significance testing following updates with new trials remains a serious concern (Brok 2009; Thorlund 2009; Wetterslev 2008; Wetterslev 2009). As a result, spurious P values due to systematic errors from trials with high risk of bias, outcome reporting bias, publication bias, early stopping for benefit and small trial bias may result in false conclusions. In a single trial, interim analysis increases the risk of type 1 errors. In order to avoid type 1 errors, group sequential monitoring boundaries (Lan 1983) are used to decide whether a trial could be terminated early because of a sufficiently small P value; thus, the cumulative Z‐curve crosses the monitoring boundary.

Equally, sequential monitoring boundaries can be applied to meta‐analyses and are labelled ’trial sequential monitoring boundaries’ (TSMBs). In ’trial sequential analysis’ (TSA), the addition of each new trial in a cumulative meta‐analysis is viewed as an interim meta‐analysis, which provides useful information on the need for additional trials (Wetterslev 2008).

It is appropriate and wise to adjust new meta‐analyses for multiple testing on accumulating data to control the overall type 1 error risk in cumulative meta‐analysis (Pogue 1997; Pogue 1998; Thorlund 2009; Wetterslev 2008).

When using TSA, if the cumulative Z‐curve crosses the boundary, there is an indication of a sufficient level of evidence having been reached, and as a consequence one may conclude that no further trials may be needed. However, evidence is insufficient to allow a conclusion if the Z‐curve does not cross the boundary or does not surpass the required information size.

In order to construct the TSMBs, one needs a required information size which is calculated as the least number of participants required in a well‐powered single trial with low risk of bias (Brok 2009; Pogue 1998; Wetterslev 2008).

In this updated review, we adjusted the required information size for heterogeneity with the diversity adjustment factor (Wetterslev 2009). We applied TSA, as it prevents an increase in the risk of type 1 errors (20%). If the actual accrued information size was too small, we provided the required information size given the actual diversity (Wetterslev 2009)

Subgroup analysis and investigation of heterogeneity

We conducted the following subgroup analyses:

The effect of AT III in participants given heparin (all types and doses) versus participants not given heparin
Comparing estimates of the pooled intervention effect in trials with low risk of bias to estimates from trials with high risk of bias (i.e. trials having at least one inadequate risk of bias component)
Duration of drug administration (up to one week, more than one week)
Completeness of follow‐up
Comparing the pooled intervention effect in trials with a follow‐up that was longer than the median follow‐up with trials having a follow‐up equal to or shorter than the median follow‐up of trial participants. This was in order to detect a possible dependency of the estimate of intervention effect with length of follow‐up
The effect of AT III in the trauma population
The effect of AT III in obstetrics (eclampsia, pre‐eclampsia)
The effect of AT III in paediatrics (we defined an age below 18 years for our inclusion criteria)
The effect of AT III in sepsis and DIC

If analyses of various subgroups were significant, we performed a test of interaction (Altman 2003). We considered P values < 0.05 as indicating significant interaction between the AT III effect and subgroup category.

We included entire trials for subgroup analysis of trauma, obstetric, and paediatric participants.

Sensitivity analysis

We decided to carry out a sensitivity analysis on the results by applying fixed‐effect and random‐effects models to assess the impact of heterogeneity on our results.

Summary of findings

We used the principles of the GRADE approach to provide an overall assessment of the evidence relating to all of our outcomes. We constructed a 'Summary of findings' table using the GRADEpro software. As outcomes of public interest, we chose to present: mortality, bleeding events, incidence of respiratory failure not present at admission, duration of mechanical ventilation, length of stay in hospital, mean length of stay in ICU and overall mortality among patients with severe sepsis and DIC (see Table 1).

for the main comparison.

AT III compared to control for critically ill patients
Setting: Worldwide  Intervention: AT III  Comparison: Control Patient or population: critically ill participants
Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect  (95% CI)	No of Participants  (studies)	Quality of the evidence  (GRADE)	Comments
	Risk with control	Risk with AT III
Mortality (subgroup analysis on bias risk)	Study population		RR 0.95  (0.88 to 1.03)	3882  (29 studies)	⊕⊕⊕⊝  moderate^1,2	9 trials had low risk of bias, 20 trials high risk of bias. Trial sequential analysis (TSA) adjusted RR 0.95 (95% CI 0.87 to 1.04).
	385 per 1000	366 per 1000  (339 to 396)
	Moderate
	310 per 1000	295 per 1000  (273 to 320)
Bleeding events	Study population		RR 1.58 (1.35 to 1.84)	3019  (11 studies)	⊕⊕⊕⊝ moderate³	6 trials had low risk of bias, 5 trials high risk of bias. Based on the TSA analysis, there seem to be evidence indicating that AT III increases risk of bleeding (Figure 1). TSA adjusted meta‐analysis yields a RR of 1.85 (95% CI 1.35 to 1.85).
	385 per 1000	366 per 1000  (339 to 396)
	Moderate
	67 per 1000	102 per 1000  (87 to 119)
Incidence of respiratory failure not present at admission	Study population		RR 0.93  (0.76 to 1.14)	2591  (6 studies)	⊕⊕⊕⊝  moderate^1,4	5 trials had low risk of bias, 1 trial high risk of bias.
	106 per 1000	98 per 1000  (80 to 120)
	Moderate
	317 per 1000	294 per 1000  (241 to 361)
Duration of mechanical ventilation	The mean duration of mechanical ventilation in the intervention group was 2.2 more (1.21 fewer to 5.6 more)		‐	190  (3 studies)	⊕⊝⊝⊝  very low⁵	2 trials had low risk of bias, 1 trial high risk of bias
Length of stay in hospital	The mean length of stay in hospital in the intervention group was 1.1 more (7.16 fewer to 9.36 more)		‐	202  (4 studies)	⊕⊝⊝⊝  very low⁶	2 trials had low risk of bias, 2 trials high risk of bias
Mean length of stay in ICU	The mean length of stay in ICU in the intervention group was 0.24 more (1.34 fewer to 1.83 more)		‐	376  (7 studies)	⊕⊝⊝⊝  very low^1,7	3 trials had low risk of bias, 4 trials high risk of bias
Overall mortality among patients with severe sepsis & DIC	Study population		RR 0.95 (0.88 to 1.03)	2858  (12 studies)	⊕⊝⊝⊝  very low^1,8	4 trials had low risk of bias, 8 trials high risk of bias
	462 per 1000	439 per 1000  (407 to 476)
	Moderate
	392 per 1000	372 per 1000  (345 to 404)
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).  CI: Confidence interval; RR: Risk ratio
GRADE Working Group grades of evidence  High quality: We are very confident that the true effect lies close to that of the estimate of the effect  Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different  Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect  Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

	AT III n/N	Control n/N	Low risk of bias trials RR (95% CI)	High risk of bias trials RR (95% CI)	Overall RR (95% CI)	Heterogeneity
Overall mortality (subgroup analysis on random sequence generation)¹	720/1915	757/1967	0.95 (0.88 to 1.03)	0.98 (0.79 to 1.21)	0.95 (0.88 to 1.03)	I² = 0%
Overall mortality (subgroup analysis on allocation concealment)²	720/1915	757/1967	0.96 (0.88 to 1.04)	0.93 (0.75 to 1.15)	0.95 (0.88 to 1.03)	I² = 0%
Overall mortality (subgroup analysis on blinding)³	720/1915	757/1967	0.96 (0.88 to 1.04)	0.94 (0.77 to 1.14)	0.95 (0.88 to 1.03)	I² = 0%
Overall mortality (subgroup analysis on completeness of follow‐up)⁴	720/1915	757/1967	0.95 (0.88 to 1.02)	1.08 (0.77 to 1.51)	0.95 (0.88 to 1.03)	I² = 0%
Overall mortality (subgroup analysis on ITT)⁵	705/1856	736/1895	0.98 (0.79 to 1.22)	0.95 (0.88 to 1.03)	0.95 (0.88 to 1.03)	I² = 0%

Trial	AT III			Control			Mean Difference
	Mean	SD	Total	Mean	SD	Total	IV, Fixed, 95% CI
Eisele 1998	0.3	0.5	15	0.5	0.7	13	‐0.20 (‐0.66 to 0.26)

Date	Event	Description
4 January 2016	New citation required but conclusions have not changed	A new lead author (Allingstrup M) has updated this review in collaboration with the original authors. In this updated review we chose to include trials which had only been published as abstracts (Balk 1995; Blauhut 1985; Muntean 1989; Palareti 1995; Schuster 1997). These trials report mortality data from 236 participants. The trial abstracts do not provide us with much data to examine. However, we provide the limited mortality data that we were able to retrieve from these trials. We classify all of these trials as being at high risk of bias. The conclusions have not changed in this updated review.
4 January 2016	New search has been performed	We searched the databases until 27 August 2015. We included 10 new antithrombin III (AT III) trials in this updated review. This review now has 30 included studies in total (3933 participants). We have updated the Methods section, included full 'Risk of bias' tables and 'Summary of findings' tables. We applied trial sequential analysis (TSA).
11 February 2013	Amended	Contact details updated; order of tables corrected
12 October 2010	Amended	Contact details updated.
11 May 2010	Amended	Contact details updated.
7 August 2008	Amended	Minor edits to text
12 May 2008	Amended	converted to new Review format

Database	Search terms
The Cochrane Central Register of  Controlled Trials (CENTRAL)	#1 MeSH descriptor: (Antithrombin III) explode all trees  #2 (antithrombin III or AT III):ti,ab  #3 #1 or #2
CINAHL (EBSCO host)	S1 TI ( antithrombin) OR AB ( antithrombin)  S2 (random* or ((controlled or clinical) N3 trial) or placebo or multicenter or prospective) or ((blind or mask*) and (single or double or triple or treble))  S3 S1 and S2
MEDLINE (Ovid SP)	1. Antithrombins/ or AT?III.mp. or antithrombin*.mp.  2. ((randomised controlled trial or controlled clinical trial).pt. or randomized.ab. or placebo.ab. or clinical trials as topic.sh. or randomly.ab. or trial.ti.) not (animals not (humans and animals)).sh.  3. 1 and 2 ()  (()))
EMBASE (Ovid SP)	1. antithrombin/ or exp antithrombin III/ or (AT?III or antithrombin).ti,ab.  2. (randomized‐controlled‐trial/ or randomization/ or controlled‐trial/ or multicenter‐trial/ or phase‐3‐clinical‐trial/ or phase‐4‐clinical‐trial/ or double‐blind‐procedure/ or single‐blind‐procedure/ or (random or cross?over* or multicenter* or factorial* or placebo* or volunteer).mp. or ((singl or doubl* or trebl* or tripl) adj3 (blind or mask*)).ti,ab. or (latin adj square).mp.) not (animals not (humans and animals)).sh.  3. 1 and 2
Science Citation Index EXPANDED	#1 TS=(antithrombin* or AT?III)  #2 TS=(random* or ((controlled or clinical) SAME trial) or placebo or multicenter or prospective) or TS=((blind* or mask*) SAME (single or double or triple or treble))  #3 #1 and #2
Latin American Caribbean Health Sciences Literature (LILACS	"antithrombin$" or "AT III"

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mortality (subgroup analysis on bias risk)	29	3882	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
1.1 Trials with low bias risk	9	2915	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.88, 1.04]
1.2 Trials with high bias risk	20	967	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.77, 1.14]
2 Overall mortality (subgroup analysis on median follow‐up)	28	3848	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
2.1 Mortality in trials with follow up less than median of all trials	18	1024	Risk Ratio (M‐H, Fixed, 95% CI)	0.93 [0.77, 1.13]
2.2 Mortality in trials with follow up longer than median of all trials	10	2824	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.88, 1.04]
3 Overall mortality (subgroup analysis on duration of intervention)	28	3848	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
3.1 Median duration of AT III intervention equal to or less than one week	25	3640	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
3.2 Median duration of AT III intervention longer than one week	3	208	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.59, 1.34]
4 Overall mortality (trauma)	2	68	Risk Ratio (M‐H, Fixed, 95% CI)	2.15 [0.81, 5.72]
4.1 Trials with high bias risk	1	28	Risk Ratio (M‐H, Fixed, 95% CI)	3.43 [0.15, 77.58]
4.2 Trials with low bias risk	1	40	Risk Ratio (M‐H, Fixed, 95% CI)	2.0 [0.72, 5.59]
5 Overall mortality (obstetrics)	2	332	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.33, 3.21]
5.1 Overall maternal mortality, trials with low bias risk	2	174	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
5.2 Overall foetal and neonatal mortality, trials with low bias risk	2	158	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.33, 3.21]
6 Overall mortality (paediatrics)	4	365	Risk Ratio (M‐H, Fixed, 95% CI)	1.44 [0.73, 2.83]
6.1 Trials with low bias risk	2	182	Risk Ratio (M‐H, Fixed, 95% CI)	1.6 [0.54, 4.72]
6.2 Trials with high bias risk	2	183	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.56, 3.15]
7 Overall mortality (heparin; Warren 2001 as a trial with adjuvant heparin therapy)	26	3779	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
7.1 Trials with complete or partially adjuvant heparin therapy	16	3121	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.88, 1.04]
7.2 Trials without adjuvant heparin	10	658	Risk Ratio (M‐H, Fixed, 95% CI)	0.93 [0.71, 1.23]
8 Overall mortality (heparin; Warren 2001 as a trial without adjuvant heparin therapy)	26	3779	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
8.1 Trials with complete or partially adjuvant heparin therapy	15	807	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.79, 1.17]
8.2 Trials without adjuvant heparin	11	2972	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
9 Overall mortality (heparin; Warren 2001 data split based on heparin administration)	26	3779	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
9.1 Trials with complete or partially adjuvant heparin therapy	16	2423	Risk Ratio (M‐H, Fixed, 95% CI)	1.00 [0.91, 1.09]
9.2 Trials without adjuvant heparin	11	1356	Risk Ratio (M‐H, Fixed, 95% CI)	0.88 [0.77, 1.00]
10 Overall mortality among patients with severe sepsis & DIC	12	2858	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
10.1 Trials with low bias risk	4	2529	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.04]
10.2 Trials with high bias risk	8	329	Risk Ratio (M‐H, Fixed, 95% CI)	0.87 [0.64, 1.20]
11 Complications during the inpatient stay specific to the trial intervention	3	2454	Risk Ratio (M‐H, Random, 95% CI)	1.26 [0.83, 1.92]
11.1 Trials with low bias risk	2	2429	Risk Ratio (M‐H, Random, 95% CI)	1.62 [0.96, 2.73]
11.2 Trials with high bias risk	1	25	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.51, 1.66]
12 Complications during the inpatient stay not specific to the trial intervention	2	65	Risk Ratio (M‐H, Random, 95% CI)	0.71 [0.08, 6.11]
12.1 Trials with low bias risk	1	40	Risk Ratio (M‐H, Random, 95% CI)	3.0 [0.13, 69.52]
12.2 Trials with high bias risk	1	25	Risk Ratio (M‐H, Random, 95% CI)	0.31 [0.04, 2.57]
13 Complication specific to the trial intervention other than bleeding	3	187	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.42, 1.25]
13.1 Trials with low bias risk	1	60	Risk Ratio (M‐H, Fixed, 95% CI)	0.75 [0.18, 3.07]
13.2 Trials with high bias risk	2	127	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.40, 1.30]
14 Bleeding events	11	3019	Risk Ratio (M‐H, Fixed, 95% CI)	1.58 [1.35, 1.84]
14.1 Trials with low bias risk	6	2791	Risk Ratio (M‐H, Fixed, 95% CI)	1.58 [1.35, 1.85]
14.2 Trials with high bias risk	5	228	Risk Ratio (M‐H, Fixed, 95% CI)	1.57 [0.71, 3.49]
15 Amount of red blood cells administered	4	137	Mean Difference (IV, Random, 95% CI)	138.49 [‐391.35, 668.34]
15.1 Trials with low bias risk	1	35	Mean Difference (IV, Random, 95% CI)	‐600.0 [‐899.18, ‐300.82]
15.2 Trials with high bias risk	3	102	Mean Difference (IV, Random, 95% CI)	595.10 [‐287.14, 1477.34]
16 Incidence of surgical intervention	3	103	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.85, 1.27]
16.1 Trials with low bias risk	3	103	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.85, 1.27]
17 Severity of sepsis I	3	156	Mean Difference (IV, Random, 95% CI)	‐1.24 [‐2.18, ‐0.29]
17.1 Final MOF score among survivors, trials with low bias risk	1	88	Mean Difference (IV, Random, 95% CI)	‐0.70 [‐1.22, ‐0.18]
17.2 Final MOF score among survivors, trials with high bias risk	2	68	Mean Difference (IV, Random, 95% CI)	‐1.92 [‐3.05, ‐0.78]
18 Severity of sepsis II	3	102	Mean Difference (IV, Fixed, 95% CI)	‐2.18 [‐4.36, ‐0.00]
18.1 Final APACHE I & II scores among survivors, trials with high bias risk	3	102	Mean Difference (IV, Fixed, 95% CI)	‐2.18 [‐4.36, ‐0.00]
19 Incidence of respiratory failure not present at admission	6	2591	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.76, 1.14]
19.1 Trials with low bias risk	5	2564	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.77, 1.22]
19.2 Trials with high bias risk	1	27	Risk Ratio (M‐H, Random, 95% CI)	0.73 [0.45, 1.18]
20 Duration of mechanical ventilation	3	190	Mean Difference (IV, Fixed, 95% CI)	2.20 [‐1.21, 5.60]
20.1 Trials with low bias risk	2	162	Mean Difference (IV, Fixed, 95% CI)	2.26 [‐1.69, 6.22]
20.2 Trials with high bias risk	1	28	Mean Difference (IV, Fixed, 95% CI)	2.0 [‐4.68, 8.68]
21 Length of stay in hospital	4	202	Mean Difference (IV, Random, 95% CI)	1.10 [‐7.16, 9.36]
21.1 Trials with low bias risk	2	89	Mean Difference (IV, Random, 95% CI)	‐5.67 [‐16.24, 4.90]
21.2 Trials with high bias risk	2	113	Mean Difference (IV, Random, 95% CI)	7.17 [2.75, 11.59]
22 Mean length of stay in ICU	7	376	Mean Difference (IV, Fixed, 95% CI)	0.24 [‐1.34, 1.83]
22.1 Trials with low bias risk	3	195	Mean Difference (IV, Fixed, 95% CI)	‐0.73 [‐3.41, 1.95]
22.2 Trials with high bias risk	4	181	Mean Difference (IV, Fixed, 95% CI)	0.77 [‐1.20, 2.74]

Methods	2‐group parallel randomized clinical trial  ITT: no  No sample size calculation was reported
Participants	32 patients in the ICU with plasma AT III levels less than 70%. All participants included in the trial within 2 days after admission to the ICU AT III group: 16 participants, 8 men, median age: 63.5 years. Median APACHE II score on inclusion: 14, TISS : 34. Reason for admission: surgery 7 patients, trauma 4 patients, infection 3 patients, and other causes: 2 patients Control group: 16 participants, 9 men, median age: 66 years. Median APACHE II score on inclusion: 15, TISS : 39. Reason for admission: surgery 5 patients, trauma 4 patients, infection 5 patients, and other causes: 2 patients Exclusion criteria: under 18 years old, liver disease, HIV infection, severe brain damage, patients admitted for postoperative pain relief only, anorexia nervosa, and pregnancy
Interventions	AT III: concentrate by intravenous infusion for 20 ‐ 30 minutes twice daily as long as AT III < 90%, in a dose intended to raise the level above 100% until the patients were discharged from the ICU. First dose: 2000 ‐ 4000 IU, total amount: 3500 ‐ 17000 IU Control: no placebo Unfractionated heparin 2500 or 5000 IU x 2 or x 3 daily was given subcutaneously to all patients for thromboprophylaxis. If continuous arteriovenous haemofiltration for acute anuria, then 20000 ‐ 40000 IU heparin per 24 hours was administered as continuous infusion. Blood samples from each patient were taken daily for 7 days or until discharge. Standard intensive care treatments were administered to all patients in both groups.
Outcomes	Primary: mortality Secondary: days in ICU, bleeding and transfusion, AT III, CRP, tissue plasminogen activator inhibitor, partial thromboplastin time, prothrombin complex (prothrombin time), fibrinogen degradation products, lactoferrin/serum, lactoferrin/plasma, lysozyme, side effects, APACHE II score and TISS (during the first 24 hours)
Notes	Country: Sweden  Letter sent to authors in November 2005. Reply received in December 2005  2 participants randomized but not evaluated: 1 transferred to another hospital, the other had received AT III although randomized to the non‐AT III group. There were 3 cases of cross‐over: these participants received AT III despite being allocated to the control group. These participants were evaluated up to the day when they received AT III. No side effects were reported. Funding bias: No funding by industry
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random computer number generator
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes
Blinding of participants and personnel (performance bias)   All outcomes	Unclear risk	Unclear
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	Unclear
Incomplete outcome data (attrition bias)   All outcomes	Low risk	No withdrawals were specified.
Selective reporting (reporting bias)	Unclear risk	Unclear
Other bias	Unclear risk	Unable to assess, insufficient information

Methods	2‐group randomized clinical trial  ITT: yes  No sample size calculation was reported
Participants	29 patients with post‐necrotic cirrhosis undergoing liver transplantation were randomized to receive AT III (13 participants) or to control group (no placebo, 16 participants) ‐ before the induction of anaesthesia and during surgery. AT III group: 13 men, 4 patients with cryptogenetic cirrhosis, 4 with post‐necrotic cirrhosis, 5 with alcoholic cirrhosis, average age 44 ± 9 years, duration of surgery (mins): 625 ± 68  Control group: 16 men, 5 patients with cryptogenetic cirrhosis, 7 with post necrotic cirrhosis, 4 with alcoholic cirrhosis, average age 42 ± 9 years, duration of surgery (mins): 642 ± 113
Interventions	AT III: administered by bolus infusion before the induction of anaesthesia in order to obtain a pre‐operative activity of 100%. Thereafter 1000 units per hour were given by continuous infusion until the end of surgery. No systemic heparinization Control: no placebo
Outcomes	Mortality. Blood loss, transfusion requirements, activation of coagulation and fibrinolysis (thrombin‐antithrombin complexes), activated partial thromboplastin time, prothrombin time, thrombin time, reptilase time, expressed as ratio, fibrinogen, plasminogen, alfa2‐antiplasmin, AT III, platelet count, thrombin‐antithrombin complexes, total fibrinogen, fibrinogen and fibrin degradation products
Notes	Country: Italy  Letter sent to authors in January 2006, no reply received Funding bias: Unclear. Not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias)   All outcomes	Unclear risk	Not stated
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias)   All outcomes	Low risk	No withdrawals were specified.
Selective reporting (reporting bias)	Unclear risk	Not stated
Other bias	Unclear risk	Not stated

Methods	3‐group parallel randomized clinical trial  ITT: no  No sample size calculation was reported
Participants	51 patients with DIC and septic shock Inclusion criteria: AT III activity < 70% and at least 3 of the following: platelet count < 100, thrombin time > 24 sec, thrombin coagulase time > 22 sec, fibrinogen level < 150 mg/dl, ethanol gelatin test positive
Interventions	Control group 1: Heparin: iv heparin 3000 IU followed by continuous infusion of 250 IU/h Intervention group 2: AT III substitution with the aim to keep ATIII activity constantly around 100% Intervention group 3: Same AT III substitution as group 2 with heparin 1000 IU iv and continuous infusion of 100 IU/h
Outcomes	Blood loss, concentration of ATIII, duration of symptoms of DIC, platelet count, esterase inhibitor level, blood loss
Notes	Country: Austria  No primary endpoint, unable to retrieve additional data from authors despite several attempts to contact them. 12 participants died during the trial but no data on distribution between the groups except no statistically significant difference. Funding bias: No information
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias)   All outcomes	Unclear risk	Not stated
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias)   All outcomes	High risk	Unable to retrieve relevant data on mortality
Selective reporting (reporting bias)	Unclear risk	No information or protocol available
Other bias	Unclear risk	Unable to assess, insufficient information

Methods	Randomized clinical trial  ITT: yes  No sample size calculation was reported
Participants	Multicentre, multinational trial of patients admitted to ICU AT III group: 20 participants, 11 men, mean age: 57 ± 16 yrs, weight (kg): 71 ± 14, height (cm): 171 ± 9 Underlying disease: peritonitis 2, mediastinitis 1, neoplasia (non‐haematologic) 4, others: 12. Severity of sepsis at trial entry (mean ± SD): APACHE II: 13.5 ± 5.1, MOF: 6.1 ± 2.1, OFS:1.2 ± 0.9, AT III activity: 45.7 ± 14.4% Coagulation failure: 3, acute hepatic dysfunction: 5, acute renal dysfunction: 8, acute respiratory dysfunction: 8, acute neurological dysfunction: 6. Control group: 22 patients, 10 men, mean age: 58 ± 14 yrs, weight (kg): 73 ± 15, height (cm): 169 ± 8 Underlying disease: peritonitis 3, mediastinitis 1, adult respiratory distress syndrome 1, acute pancreatitis 3, neoplasia (non‐haematologic) 3, other: 11. Severity of sepsis at trial enter (mean ± SD): APACHE II: 15.5 ± 5.7, MOF: 6.7 ± 2.0, OFS: 0.9 ± 0.8, AT III activity: 49.0 ± 19.1%. Coagulation failure: 2, acute hepatic dysfunction: 8, acute renal dysfunction: 8, acute respiratory dysfunction: 6, acute neurological dysfunction: 10 Inclusion criteria: < 80 and > 18 years old; fulfilled the following criteria within 6‐hr window prior to initiation of treatment: 1) clinical evidence of sepsis with a suspected source of infection; 2) temperature rectally > 38.5º C or < 35.5º C; 3) leukocyte count > 10000/mm³ or < 3500. Furthermore 3 of the following had to be fulfilled: a) heart rate > 100/min; b) breath rate > 24/min or mechanical ventilation because of septic indication; c) hypotension, sys BP < 90 mm Hg when no vasoactive agent or fluid replacement; d) platelet count < 100,000/mm³; e) lactate > 1.6 mmol/l; f) urine output < 20 ml/h. Exclusion criteria: a) heparin (except sc low dose); b) malignancies (incurable with metastases); c) haematologic neoplasia (except complete remission); d) chronic treatment with high‐dose immunosuppressive drugs; e) high‐dose NSAID within previous 2 days; f) known bleeding disorder; g) ongoing massive surgical bleeding; h) multiple organ failure, at least 4 organs involved existing for over 24 hrs; i) acute myocardial Infarction; j) chronic compensated organ dysfunction (chronic liver disease, dialysis, NYHA 3 ‐ 4); k) complicated pre‐existing diabetes mellitus; l) severe obstructive pulmonary disease; m) burn; n) AIDS; o) transplant; p) severe cranial trauma and/or pathologic changes on CT and GCS < 6; q) pregnancy; r) treatment with plasma expanders (Haes); s) prior enrolment in the trial or another clinical trial within the last 30 days
Interventions	Experimental: AT III iv loading dose: 3000 units AT III, maintenance 1500 IU every 12 hours, 5 days treatment, cumulative dose: 18,000 IU Control: placebo equivalent amounts, unknown agent Standard intensive care treatment in both groups
Outcomes	Primary: 30‐day all‐cause mortality Secondary: survival days, days in ICU, safety (bleeding and transfusion), MOFS, APACHE II, OSFS, AT III activity, AT III plasma concentration, resolution of acute pre‐existing organ dysfunction (neurological, respiratory, renal, hepatic and coagulation) and incidence of organ dysfunction
Notes	Country: Germany, Belgium, the Netherlands  A letter sent to authors in December 2005, no answer received APACHE II, MOF and OSF scores were calculated on days 1, 2, 3, 7, 10, 20 and 30.  No adverse events reported Funding bias: AT III by Kybernin R Centeon Pharma GmbH, Marburg, Germany. No additional information provided
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias)   All outcomes	Unclear risk	Not stated
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias)   All outcomes	Low risk	No indications of incomplete data
Selective reporting (reporting bias)	Unclear risk	Unable to assess
Other bias	Unclear risk	Unable to assess, insufficient information

Methods	2‐group parallel prospective randomized trial  ITT: no  No sample size calculation was provided
Participants	28 patients with purely traumatic brain injury and no other major trauma AT III group: 13 participants, 10 men, mean age: 48 yrs. Mean APACHE II score: 14.2, mean GCS: 7.7, median: 7.0; 50% had positive blood alcohol detection Control group: 15 participants, 10 men, mean age: 44 years. Mean APACHE II score: 14.8, mean GCS: 7.5, median: 7.0; 50% had positive blood alcohol detection Inclusion criteria: 1) 14 ‐ 70 yrs old; 2) brain injury was CT‐verified and assessed by GCS; 3) only GCS between 4 ‐ 12 included; 4) inclusion within 12 hrs from the time of injury Exclusion criteria: 1) ongoing dialysis‐dependent renal disorder; 2) bleeding or coagulation disorder such as haemophilia or von Willebrand's disease; 3) anticoagulant therapy
Interventions	AT III: 60 IU/kg body weight initially. 8 and 16 hrs later an additional 20 IU/kg body weight was given ‐ a total of 100 IU/kg body weight during 24 hrs. The doses were adjusted to the nearest 500 IU. Duration: 24 hrs. Average total dose of AT given was 8269 ± 1562 IU Control: no placebo Both groups received additional treatment according to local standards for brain injury including surgery, ventricular drain, or intraparenchymatous intracranial pressure (ICP) device, moderate hyperventilation (pCO₂ 4 ‐ 4.5 kPa), sedation, drainage of cerebrospinal fluid, low‐dose barbiturates, mannitol infusion, inotropic drugs, clonidine and dihydroergotamine. Treatment goals were ICP < 20 mm Hg and CPP > 60 mm Hg.  LMWH 2500 IU sc only to a random group of participants in few events (1 in AT group and 3 in control group). 3 participants in each group received FFP for volume replacement.
Outcomes	Primary outcome: time of coagulopathy in participants with brain contusion and with or without intracranial haemorrhage, coagulation parameters improvement: soluble fibrin (SF), AT III‐activity, D‐dimer, thrombin‐antithrombin complex (TAT), platelet count, prothrombin complex and fibrinogen, mortality at 3 months Secondary: duration of mechanical ventilation, APACHE II score (slightly modified in order to estimate the severity of illness), improved outcome assessed by GCS (once daily and at 3 months), brain injury progress monitored by CT, bleeding events, days with mechanical ventilation, need for intensive care, and evaluation of severe disability
Notes	Country: Sweden  Letter sent to authors in December 2005, no answer received. 2 withdrawals (late presentation of exclusion criteria and a revoked consent), 1 late exclusion resulting from the revelation of improper dosage of antithrombin because of incorrect information regarding body weight 1 case of cross‐over. 1 participant in the control group was given AT III by the attending physician as part of the treatment for a septic reaction. Partially missing data on this participant Funding bias: This trial was supported by Pharmacia & Upjohn, Stockholm, Sweden. They provided antithrombin concentrate and funded the trial.
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Unclear
Allocation concealment (selection bias)	Low risk	Sealed randomization envelopes were opened in numerical order
Blinding of participants and personnel (performance bias)   All outcomes	High risk	Not blinded. Open
Blinding of outcome assessment (detection bias)   All outcomes	High risk	Open‐label. No blinding
Incomplete outcome data (attrition bias)   All outcomes	Low risk	No dropouts or withdrawals were specified.
Selective reporting (reporting bias)	Low risk	Published report appears to repot all expected outcomes.
Other bias	Low risk	Appears free of such biases

Methods
Participants	49 people undergoing haematopoietic stem cell transplantation AT III group: 24 participants, 10 men. Mean age (SD): 46.1 ± 10.3 yrs. Underlying disease: acute myeloid leukaemia 5, breast carcinoma 8, chronic myeloid leukaemia 1, multiple myeloma 3, lymphoma 7 Control group: 25 participants, 11 men. Mean age (SD): 46.0 ± 10.5 yrs. Underlying disease: acute lymphocytic leukaemia 1, acute myeloid leukaemia 4, breast carcinoma 4, chronic lymphocytic leukaemia 2, chronic myeloid leukaemia 4, Hodgkin's disease 1, multiple myeloma 3, lymphoma 6 Inclusion criteria: malignant disease admitted for HSCT, not committed to other confounding clinical trials, English their first language (to allow reliable use of the mini mental status examination)
Interventions	AT III: 70 U/kg within 24 hrs of organ dysfunction detection, followed by 50 U/kg 8,16, 48 and 72 hrs later. Total dose of AT III: 270 U/kg. Estimated to provide an increment of about 250% activity above pretreatment levels after the 3rd dose. Mean total dose: 20,520 U/participant based on the mean weight of the randomized participants (76 kg) Control: 5% human albumin, volume equal to the calculated volume of AT III concentrate
Outcomes	Primary: mortality, severity‐of‐illness score, length of hospital stay Secondary: daily screening for pulmonary, hepatic or CNS dysfunction, MODS. Correlation between AT III, number of organ failure and MODS. Number of participants progressing from single through multiple organ dysfunction
Notes	Country: USA  Letter sent to authors in December 2005, no answer received.  One participant was randomized and received the 1st dose of the trial drug based on an erroneous laboratory report. This participant was not included in the final analysis.  Organ dysfunction defined as: 1) CNS ‐ a drop in the score of standardized mini mental status examination of at least 4 points from the pre‐chemotherapy score; 2) pulmonary ‐ finger oximetry reading of SpO₂ < 90% on 2 occasions on the same day separated by at least 2 hours; 3) peptic ‐ a combination of bilirubin > 2.0 mg%, a weight gain of > 5% over pre‐chemotherapy weight, and abdominal pain of possible hepatic origin  Participants with single‐organ dysfunction with a concomitant AT III activity of < 84% of normal were defined as having MODS Funding bias: Trial drugs were provided by Baxter Healthcare, Glendale, CA, USA. No additional information is provided
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated list of random numbers
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes
Blinding of participants and personnel (performance bias)   All outcomes	Low risk	An unblinded research pharmacist reconstituted the requisite volume of trial drug and provided it to the ward personnel in unmarked containers.
Blinding of outcome assessment (detection bias)   All outcomes	Low risk	Double‐blinded
Incomplete outcome data (attrition bias)   All outcomes	Low risk	No dropouts or withdrawals were specified.
Selective reporting (reporting bias)	Low risk	Unable to assess adequately but published report does not appear to exclude outcomes
Other bias	Low risk	Appears to be free of other biases

Methods	2‐group parallel randomized controlled trial  ITT: yes  No sample size calculation was provided
Participants	Patients with AT III activity of < 70% admitted to the ICU. Patients with an initial AT activity > 70% monitored daily and were randomized into the trial if their AT activity at any time during their stay fell below 70%. AT III group: 44 participants, median age: 49 yrs (range 19 ‐ 78). Admission AT III activity: 51% (range 12 ‐ 68); APACHE II score median: 16 (range 6 ‐ 33) Control group: 49 participants, median age: 49 yrs (range 16 ‐ 77). Admission AT III activity: 50% (range 12 ‐ 64); APACHE II score median: 14 (range 4 ‐ 26) Exclusion criteria: acute or chronic renal failure prior to admission to the ICU. If readmitted to ICU, the participants were allocated to the same randomization as on their previous admission. Participants were excluded if they stayed less than 4 days on ICU.  10 liver transplant recipients and 15 participants with septicaemia, major trauma, or following major surgery in each group
Interventions	Treatment: AT III, aiming at 120%. Loading dose was calculated from the initial AT III activity and the participant's weight ((120‐AT III activity (%)) x weight (kg)). Maintenance doses were given iv over 10 mins. Treatment was continued until the participant was discharged from the ICU, twice daily. Control: no placebo Standard intensive care treatment to all participants
Outcomes	Primary: mortality, coagulation parameters (AT III activity, AT‐antigen concentration, fibrinogen concentration, platelet count). Renal function impaired if creatinine clearance < 20 ml/min at any time during their stay on the ICU Secondary: days in ICU, side effects, APACHE II
Notes	Country: UK  Letter sent to authors in November 2005, no answer received. 81 participants had an AT III activity below 70% on admission to the ICU and in a further 12 participants the plasma AT III fell below 70% whilst on the ICU. Thus a total of 93 patients were randomized: 44 to the treatment arm and 49 in the no‐treatment arm. 9 participants in the AT III arm did not receive AT III replacement; 3 died before treatment began; and 6 were transferred from the ICU within a few hours of randomization. A total of 35 participants received AT III replacement. Of these 25 remained on the ICU for at least 4 days. 32 participants in the control arm remained on the ICU for at least 4 days. 25 of these were selected by diagnosis to act as controls. The authors provided mortality data on all participants randomized, and we have chosen to include these in our analysis. Funding bias: Unable to assess
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias)   All outcomes	High risk	Open‐label
Blinding of outcome assessment (detection bias)   All outcomes	High risk	Open‐label
Incomplete outcome data (attrition bias)   All outcomes	Unclear risk	Unable to assess
Selective reporting (reporting bias)	Unclear risk	Unable to assess
Other bias	Unclear risk	Unable to assess, insufficient information

Methods	2‐group parallel open randomized clinical trial.  ITT: Not stated
Participants	98 preterm neonates Inclusion criteria: premature infants  Exclusion criteria: Not stated
Interventions	Intervention group: n = 45. Single bolus AT III immediately after birth. Birth weight under 1500 g was given 100 U, over 1500 g 200 U Control group: n = 53, standard treatment. No details
Outcomes	Length of follow‐up: Not stated  Outcomes: Participants received artificial ventilation. Duration of artificial ventilation. Intraventricular haemorrhage and mortality
Notes	Location: Department of Gynaecology and Obstetrics, University of Graz, Austria  Trial only published as an abstract. Letter sent to authors, no reply received. Funding bias: Not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias)   All outcomes	High risk	Open‐label
Blinding of outcome assessment (detection bias)   All outcomes	High risk	Open‐label
Incomplete outcome data (attrition bias)   All outcomes	Unclear risk	Unable to assess
Selective reporting (reporting bias)	Unclear risk	Unable to assess
Other bias	High risk	Only published as abstract

Methods	Prospective randomized clinical trial  ITT: Not stated
Participants	38 patients with DIC. 26 participants in the control group, 12 participants in the intervention group. Age 16 ‐ 69 years. Gender is not described.
Interventions	Intervention group (AT III): (100% minus measured AT III%) x kg bodyweight, 1000 IU/h, max 1500 IU/day Control group (FFP): 10 ‐ 17 ml/kg, max 1000 ml/day The duration of treatment not described.
Outcomes	Mortality. Other outcomes are not described in the paper.
Notes	Country: Russia  We tried to contact the author, Nadejda Vorobeva on April 28th 2015, but received no reply. Funding bias: Supported by grants from the Arkhangelsk region Government
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias)   All outcomes	High risk	No blinding
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias)   All outcomes	Low risk	No dropouts or withdrawals were specified.
Selective reporting (reporting bias)	Unclear risk	Unable to assess
Other bias	High risk	Country: Russia Abstracts and article were written in Russian. Poorly‐described section of participants, inclusion criteria, outcome and intervention

Methods	2‐group parallel randomized multicentre clinical trial  ITT: yes  Sample size calculation reported
Participants	Critically ill population of ICU patients with severe sepsis and septic shock AT III: 1157 participants, men 62%; age mean (SD) 57 (17) years; SAPS II (SD) 49 (17); body weight mean (SD) 77 (19) kg. Underlying problem or site of infection: 1) respiratory system 35%; 2) intra‐abdominal infection 27%; 3) genitourinary system 6%; 4) injury 7%; 5) other 24%. Surgical status: A) no 54%, yes 46%. Circulatory shock: 49%; blood culture results: a) gram‐negative 15%, b) gram‐positive 15%, c) other/mixed 4%, d) not done/not verified 66%. Control: 1157 participants, men 61%; age mean (SD) 58 (17) years; SAPS II (SD) 49 (16); body weight mean (SD) 77 (20) kg. Underlying problem or site of infection: 1) respiratory system 34%; 2) intra‐abdominal infection 28%; 3) genitourinary system 8%; 4) injury 6%; 5) other 24%. Surgical status: A) no 53%, yes 47%. Circulatory shock: 47%; blood culture results: a) gram‐negative 16%, b) gram‐positive 17%, c) other/mixed 2%, d) not done/not verified 64%. Inclusion criteria: 18 years or above, and met following criteria within 6 hours: 1) clinical evidence of sepsis with a suspected source of infection; 2) body temperature (rectal or core) > 38.5º C or < 35.5º C; 3) leukocyte count > 10,000/µL or < 3500/µL. Additionally, 3 of the following 6 signs had to be met within the same 6‐hour period: a) heart rate > 100/min; b) tachypnoea > 24/min or mechanical ventilation because of septic indication; c) hypotension, systolic BP < 90 mmHg despite sufficient fluid replacement or the need for vasoactive agents to maintain systolic BP of 90 mmHg or greater; d) platelet count < 100,000/µL; e) elevated lactate above upper limits of normal range or metabolic acidosis (pH < 7.3 or BE≤ ‐10 mmol/L) not secondary to respiratory alkalosis; f) oliguria (< 20 ml/h despite sufficient fluid replacement). Exclusion criteria: a) advanced directive to withhold life‐sustaining treatment (except cardiopulmonary resuscitation); b) condition other than sepsis anticipated to be fatal within 28 days; c) pregnancy or breast feeding; d) history of hypersensitivity to trial medication; e) treatment with other investigational drugs within the last 30 days; f) treatment with an AT III concentrate within the last 48 hours; g) treatment with heparin (except sc low dose or iv line flushing) or coumarin derivatives; h) NSAID treatment within previous 2 days; i) known bleeding disorder or ongoing massive surgical bleeding; j) platelet count < 30 x 1000/µL; k) immunocompromised status; l) acute myocardial infarction (within previous 7 days); m) 3rd‐degree burns ≥ 20% of total body area; n) incurable malignancy with metastases and life expectancy of < 3 months; o) haematologic neoplasia during cytostatic treatment; p) bone marrow aplasia; q) pre‐existing dialysis‐dependent renal failure; r) end‐stage liver disease; s) transplantation (postoperative state); t) history of stroke within the last year; u) severe cranial or spinal trauma within the last year; v) planned cranial or spinal surgery (except nontraumatic lumbar puncture) within the next 48 hours
Interventions	AT III: loading dose of 6000 IU given over 30 minutes, followed by a continuous iv infusion of 6000 IU per day for 4 days, total of 30000 IU Control: equivalent volume of placebo solution (1% of human albumin) Heparin was permitted to be used in prophylactic doses as an adjunct to standard therapy. Administration of heparin was left to the attending physicians. Not all participants received heparin (698 participants received no heparin while receiving AT). Heparin dosage: unfractionated or LMWH for venous thrombosis prophylaxis (≤ 1000 IU subcutaneous per day) and heparin flushes for vascular catheter patency (iv of ≤ 2I U/kg body weight/h)
Outcomes	Primary: all‐cause mortality at 28 days (subgroup 28‐ and 90‐day survival for participants not receiving heparin). Secondary: mortality at 56 and 90 days, survival time, length of ICU stay, occurrence of new organ dysfunction within 7 days (according to logistic organ dysfunction score), severity of sepsis (SAPSII), circulatory shock index (i.e. ratio of heart rate (beats/minute) and systolic BP (mmHg) exceeded the value of 1.5); surgical interventions and bleeding events for 28 days, major bleeding if intracranial or required transfusion of > 3 units of blood, other serious adverse events, AT III plasma concentration, activated partial thromboplastin time and prothrombin time
Notes	Country: KyberSept Trial trial Group, 211 contributing centres in 19 countries including USA, Germany Letter sent to authors November 2005, reply by authors in December 2005 and January 2006. Funding bias: Aventis Behring sponsored the trial and the manuscript.
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Phone to a randomization centre, available on a 24‐hr basis. Randomization plans had been prepared in advance with a block size of 4 participants and investigators were told the medication package number to be used.
Allocation concealment (selection bias)	Low risk	Packages for individual participants consisted of vials and labels identical in appearance for antithrombin III and placebo. Central allocation
Blinding of participants and personnel (performance bias)   All outcomes	Low risk	Double‐blinding
Blinding of outcome assessment (detection bias)   All outcomes	Low risk	Double‐blinding
Incomplete outcome data (attrition bias)   All outcomes	Low risk	Reason for dropouts specified
Selective reporting (reporting bias)	Low risk	Reported outcomes prespecified in an available study protocol
Other bias	Low risk	Appears free of such biases

Study	Reason for exclusion
Aibiki 2006	This randomized controlled trial compared 2 active interventions of AT‐III, 500 U/8 hrs and 1500 U/24 hrs. Reason for exclusion: No placebo group, no control group
Dietrich 2013	41 participants scheduled for primary CABG. Reason for exclusion: elective participants with heart disease, meets our exclusion criteria: AT III administration for the reduction of cardiovascular events. No primary endpoints.
Doi 2012	Trial only published as abstract. Contains no relevant endpoints.
Hoffmann 2010	Trial only published as abstract. Trial on elective participants. Contains no relevant endpoints.
Ilias 2000	An open randomized clinical trial, evaluating the safety, pharmacokinetics and practicability of 2 different regimens of AT III treatment (intermittent bolus infusions vs continuous infusion), both aiming at a total dose of 30,000 IU AT III with concomitant heparin during a 4‐day period. Reason for exclusion: 2 different regimens of AT III treatment
Jochum 1995	This review includes 1 unpublished, not double‐blinded trial of AT III supplementation in a septic population aiming at AT III activity > 120%. AT III group (n = 20) received 2000 ‐ 8000 U/d AT III over 21 days and heparin (4 U/kg body weight/hour). Control group (n = 20) received no placebo. Outcome measures were various organ dysfunction analyses, inflammatory and coagulatory parameters and mortality (control: 80%; AT III: 65%). The results were not statistically significant. Study excluded due to lack of outcomes of relevance and since we were unable to contact the authors in order to retrieve additional information
Kanbak 2011	Randomized trial made in CABG participants. Reason for exclusion: Meets our exclusion criteria: AT III administration for the reduction of cardiovascular events. No primary endpoints.
Kim 2013	The purpose of this trial was to compare the pharmacokinetic and pharmacodynamic characteristics of 2 AT III formulations. Reason for exclusion: Trial on healthy Korean volunteers
Korninger 1987	A randomized trial of AT III in participants undergoing peritoneo‐venous shunt operation because of intractable ascites. 10 participants with alcoholic liver cirrhosis were randomized according to the stage of liver disease and pre‐operative AT III levels. AT III was infused in 5 participants, twice daily for 4 days, at a dose of 20 U/kg body weight starting 12 hours prior to operation. 5 participants were allocated to placebo. Coagulatory parameters were examined. Reason for exclusion: only published as abstract, no data on mortality
Leitner 2006	This randomized, double‐blinded, placebo‐controlled trial examined 30 healthy male volunteers. The active treatment groups received infusions of AT III to achieve levels of 200% and 500% before infusion of 2 ng/kg endotoxin. Reason for exclusion: experimental trial among healthy volunteers
Maki 1987	This randomized controlled trial compared 2 active interventions, in participants with obstetric complications. Reason for exclusion: 2 different active interventions
Mayumi 2011	Trial only published as an abstract. We assume that the abstract is a subgroup analysis of an earlier trial. We cannot contact the author as it is not possible to find contact information.
Neporada 2008B	Data based on the same trial as Neporada 2008A
Nishiyama 2006	This randomized, unblinded trial investigated the effects of AT III on coagulation, fibrinolysis, production of cytokines and adhesion molecules in abdominal aortic aneurysm repair surgery. 16 participants for Y‐shaped graft replacement of abdominal aortic aneurysm were divided into an AT III group and a control group. In the AT III group, 3000 U AT III was infused over 30 min before heparin administration and 24 hrs later. Reason for exclusion: no data on mortality, nor any data relevant for our review. We emailed the author on 17th April 2015, but received no reply.
Paparella 2014	Randomized trial made in CABG participants. Reason for exclusion: Meets our exclusion criteria: AT III administration for the reduction of cardiovascular events. No primary endpoints.
Paternoster 2000	This prospective trial evaluated the modifications of clotting and clinical parameters before and immediately after delivery amongst a pre‐eclamptic population either treated with AT III (n = 18) or acting as control (n = 21). Reason for exclusion: only published as a brief communication, no data on mortality, randomization or blinding
Paternoster 2004	In this trial, 23 pre‐eclamptic women were randomly subdivided into 2 groups: 1st group (n = 10) were treated with 3000 units AT III once daily for 5 days or until delivery, while the 2nd group (n = 13) were treated with doses of AT III sufficient to maintain at least 80% of the activity. The endpoints were the prolongation of pregnancy, assessment of the maternal bleeding and haemostasis, and inflammatory markers. Reason for exclusion: comparison of 2 different regimens of AT III
Ranucci 2013	200 participants given preoperative AT supplementation in elective participants during cardiac surgery with CPB. Reason for exclusion: elective participants with heart disease
Sawamura 2009	23 DIC participants were treated with either high‐dose (60 IU/kg/day) or low‐dose (30 IU/kg/day) antithrombin concentrates for 3 days. The trial tested the hypotheses that AT III (antithrombin) improves DIC when applied to DIC participants. Reason for exclusion: No placebo group, no control group
Scherer 1997	A randomized prospective trial examining the effects of AT III substitution in order to achieve supranormal values in participants with liver cirrhosis scheduled for liver transplantation.  19 participants were given AT III aiming at either 100% (n = 10) or 175% (n = 9) AT III activity. Control group (n = 5) received saline 0.9%. The endpoints were various coagulatory variables measured prior to AT III infusion and 60 min thereafter. Reason for exclusion: no data on mortality, 3 groups
Shimada 1994	A randomized prospective trial of AT III efficacy in hepatic resection among 24 participants with hepatocellular carcinoma. 13 participants were given 1500 IU AT III immediately before operation, during hepatectomy, and immediately after operation. Control group (n = 11) received no placebo. Coagulant and fibrinolytic profiles were determined. Reason for exclusion: no data on mortality, different population than defined in our review
Terao 1989	A randomized trial of 40 participants with pre‐eclampsia comparing AT III intervention with no treatment on coagulatory findings, gestosis index, abortion times, and incidence of newborn asphyxia. Reason for exclusion: no data on mortality
Valsecchi 2008	Only published as an abstract. Trial was terminated by the sponsor with insufficient information.
Vinazzer 1995	This review mentioned one unpublished trial of participants with DIC due to sepsis or septic shock in which 170 participants were evenly allocated to 2 groups (heparin versus AT III). This uncontrolled open clinical trial showed positive outcome of AT III substitution. Study excluded due to lack of outcomes of relevance and since we were unable to contact the authors in order to retrieve additional information

Trial name or title	EPAS
Methods	Double‐blind RCT
Participants	Women with pre‐eclampsia occurring before the 30th week of gestation
Interventions	7‐day course of antithrombin 3000 IU/day. No heparin prophylaxis will be permitted during the time of AT III administration.
Outcomes	Primary outcome: reduction of the combined endpoint of foetoneonatal mortality and severe neonatal morbidity.  Secondary outcomes: reduction in maternal complications and stay in neonatal ICU and the evaluation of the changes in coagulation and inflammation parameters.
Starting date	December 2004
Contact information	D'angelo A (1),Valsecchi L (2)  1): Coagulation Service and Thrombosis Research Unit  2): Department of Obstetrics and Gynecology, Irccs  H S. Raffaele Milano, Italy
Notes	D'angelo A,Valsecchi L; A double‐blind trial of high‐dose antithrombin supplementation in early pre‐eclampsia. Thrombosis Research. 2005; 115 Suppl 1:117 Prof. Dr. Armando D'Angelo was contacted 9th April 2015 and answer the same day. The trial results will be published in the near future.

PERMALINK

Antithrombin III for critically ill patients

Mikkel Allingstrup

Jørn Wetterslev

Frederikke B Ravn

Ann Merete Møller

Arash Afshari

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors' conclusions

Plain language summary

Summary of findings

1.

Background

Description of the condition

Description of the intervention

How the intervention might work

Why it is important to do this review

Objectives

Methods

Criteria for considering studies for this review

Types of studies

Types of participants

Types of interventions

Types of outcome measures

Primary outcomes

Secondary outcomes

Search methods for identification of studies

Electronic searches

Searching other resources

Data collection and analysis

Selection of studies

Data extraction and management

Assessment of risk of bias in included studies

Measures of treatment effect

Unit of analysis issues

Studies with multiple intervention groups

Dealing with missing data

Assessment of heterogeneity

Assessment of reporting biases

Data synthesis

Data analysis

Trial sequential analysis

Subgroup analysis and investigation of heterogeneity

Sensitivity analysis

Summary of findings

for the main comparison.

Results

Description of studies

Results of the search

2.

Types of participants

Types of interventions

Included studies

Excluded studies

Ongoing studies

Awaiting classification

Risk of bias in included studies

3.

Allocation

4.

Blinding

Incomplete outcome data

Selective reporting

Other potential sources of bias

Effects of interventions

Primary outcomes

1. Overall mortality (longest follow‐up, regardless of the period of follow‐up)

1.1. Analysis.

1.7. Analysis.

1.8. Analysis.

1.9. Analysis.

1.2. Analysis.

1.3. Analysis.

1.4. Analysis.