Structured Abstract
Background/aims
Primary simultaneous bilateral total joint arthroplasty (simBTJA) can cause postoperative anemia. Clinicians might hesitate to discharge patients who have large changes in hemoglobin [Hgb], despite Hgb levels remaining above transfusion thresholds. This study was conducted to evaluate if delta Hgb or perioperative blood loss correspond with readmission in primary simBTJA patients not transfused perioperatively.
Methods
From 2015 – 2020, a retrospective chart review of primary simultaneous bilateral total hip/knee arthroplasty cases was conducted. Preoperative and postoperative Hgb levels were obtained from our database or chart review. Exclusion criteria comprised patients who had a preoperative transfusion or transfusion postoperatively during their surgical admission, and patients not discharged home. Outcomes included whether delta Hgb or perioperative blood loss were predictive of 90-day readmission postoperatively, postoperative anemia, and transfusion during readmission.
Results
The 510 individuals undergoing primary simBTJA possessed an average preoperative Hgb of 14.1 g/dL, starting blood volume of 5012 mL, postoperative Hgb of 10.0 g/dL, delta Hgb of 3.90 g/dL, and perioperative blood loss of 1403 mL. 19 patients (3.73 %) were readmitted, with none requiring transfusion. When constructing receiver operating characteristic (ROC) curves predicting readmission from delta Hgb, a threshold of 4.1 g/dL had an area under the curve (AUC) of 0.454, a sensitivity of 0.473, and a specificity of 0.56. For ROC curves predicting readmission from perioperative blood loss, a threshold of 1144 mL had an AUC of 0.453, a sensitivity of 0.842, and a specificity of 0.297. Similar AUCs, sensitivities, and specificities were obtained when adjusting ROC curves for preoperative Hgb or starting blood volume.
Conclusions
Delta Hgb and perioperative blood loss do not predict 90-day readmission after primary simBTJA in patients not transfused perioperatively. Patients with a large delta Hgb but stay higher than a 7 g/dL restrictive transfusion threshold may have a strong capacity to overcome postoperative anemia.
1. Introduction
Simultaneous bilateral total joint arthroplasty (simBTJA) can cause a significant loss of blood volume, averaging 1400 mL (mL),1 along with a high incidence of acute postoperative anemia.2,3 There remains significant debate about the rate of utilization of allogenic blood transfusion perioperatively after undergoing simBTJA, with some studies finding high transfusion rates over 20 %,4,5 and others finding lower transfusion rates.3,6
Allogenic transfusions can be associated with many complications, such as anaphylactic reactions, hemolytic reactions, infection transmission, transfusion related acute lung injury, and immunomodulation which can elevate the odds of developing periprosthetic joint infection.7 Additionally, individuals who undergo postoperative transfusions have an increased odds for unplanned readmission.8 Given the risks of transfusion, restrictive hemoglobin (Hgb) transfusion thresholds of 7–8 g/dL or symptomatic anemia are commonly used.9,10
Despite this recommendation, clinicians may worry when discharging patients with large changes in preoperative to postoperative Hgb, despite their postoperative Hgb level being above 7–8 g/dL and being asymptomatic, worrying that they may be readmitted. This may stem from prolonged postoperative blood loss, which may result in postoperative Hgb levels declining up to four days postoperatively.11 Additionally, it may stem from legal concerns, with surgeons fearing litigation about why significant decreases in Hgb were left untreated if individuals experience complications requiring readmission after undergoing simBTJA.
The purpose of this study was to evaluate if a specific value for delta Hgb or perioperative blood loss (mL) in individuals undergoing simBTJA was associated with increased readmission in patients who were discharged with a Hgb higher than 7 g/dL and did not require perioperative allogenic blood transfusions. We predicted that regardless of delta Hgb or perioperative blood loss values, individuals who have a Hgb level of 7 g/dL or higher can be safely discharged after undergoing simBTJA without increased risk of experiencing 90-day readmission.
2. Methods
This retrospective cohort study was conducted from 2015 to 2020 with patients who underwent simBTJA. Institutional review board (IRB) approval was obtained prior to the commencement of this study. This manuscript was assembled utilizing the strengthening the reporting of observational studies in epidemiology (STROBE) guidelines.12
2.1. Data sources
The data used in this study was extracted from an institutional arthroplasty database. Among patients who had two or more preoperative or postoperative Hgb values, their medical records were manually reviewed to ascertain accurate values. Preoperative Hgb values were acquired within two months prior to surgery. Postoperative Hgb values were acquired closest to before discharge after the primary simBTJA, which was usually during the morning prior to discharge. The difference between these two values was the delta Hgb. The Nadler equation was used to calculate the starting blood volume (mL),13 while the Hemoglobin Balance equation was used to calculated perioperative blood loss (mL).14
2.2. Study criteria
Inclusion criteria comprised individuals having primary bilateral simultaneous total hip arthroplasty (bsTHA), patients undergoing bilateral simultaneous total knee arthroplasty (bsTKA), individuals discharged home after undergoing simBTJA, and cases performed from 2015 to 2020 since a nurse navigator program was available beginning in 2015, allowing for validated tracking of postoperative complications.15 Exclusion criteria comprised individuals who had incomplete data, patients who were transfused within 60 days preoperatively or during their surgical admission for simBTJA, and individuals who were discharged to a rehabilitation hospital or nursing facility after surgery.
2.3. Demographic information collected
The demographic information utilized in this study included patient age, patient sex, Charlson Comorbidity Index (CCI) that was age-adjusted, body mass index (BMI), operative time (cut to close), case type (bsTKA or bsTHA), and utilization of tranexamic acid (TXA).
2.4. World Health Organization definitions
The definition for anemia from the World Health Organization (WHO) was utilized to categorize whether patients had anemia before and after surgery. Males and females who have had menopause with a Hgb <13, and females who have not experienced menopause with a Hgb <12 were classified with anemia.16 Females 51 years and older were considered to be postmenopausal.17 Cardiovascular diseases (CVDs) were defined in accordance with the WHO and this was used to define whether individuals had CVD or not. CVD included rheumatic heart disease, coronary artery disease, peripheral arterial disease, cerebrovascular disease, history of pulmonary embolism (PE), congenital heart disease, or history of deep vein thrombosis (DVT).18
2.5. Study endpoints
The main endpoint of this study was evaluating if a specific cutoff delta Hgb or perioperative blood loss amount was predictive of increased 90-day readmission postoperatively in patients undergoing simBTJA. Emergency department visits were not included in 90-day readmissions. Secondary endpoints included patients requiring transfusion during 90-day readmissions or having postoperative anemia.
2.6. Statistical tests
While performing the statistical tests, t-tests were used to analyze parametric continuous data, and Mann-Whitney tests were implemented to analyze nonparametric continuous data. Chi-square tests or Fisher's exact tests were implemented to analyze categorical data. Statistical significance was set at a p-values <0.05. Receiver operating characteristic (ROC) curves were constructed for thresholds of delta Hgb or perioperative blood loss associated with readmission, and their associated area under the curve (AUC), sensitivity (SEN), and specificity (SPEC). ROC curves adjusted for preoperative Hgb or starting blood volume were also constructed. An AUC of 0.5 suggested bad performance of a threshold Hgb, with little to no ability to discriminate between patients who experienced 90-day readmission or not. An AUC of 0.7–0.8 had acceptable results, 0.8–0.9 had excellent results, and an AUC higher than 0.9 had outstanding predictive ability.19 The statistical tests were conducted utilizing Version 3.6.3 R Studio (Vienna, Austria).
3. Results
After incorporating study inclusion and exclusion criteria (Fig. 1), 510 primary simBTJAs were studied, comprising 139 THAs and 371 TKAs (Table 1). The mean age of included cases was 60.6 years (Standard Deviation [SD] 8.39), the mean BMI was 30.0 kg/m2 (SD 4.70), and females encompassed 51 % of the cohort (Table 1). The mean age-adjusted CCI was 2.77 (SD 1.09), preoperative coagulopathy was prevalent in 0.39 % of patients, and CVDs were prevalent in 7.84 % of patients (Table 1).
Fig. 1.
Study inclusion and exclusion flowchart.
Table 1.
Demographic characteristics table for the full cohort.
| Patient Characteristics | Patients (n = 510) |
|---|---|
| Age | 60.6 (8.39) |
| Gender: | |
| Male | 250 (49.0 %) |
| Female | 260 (51.0 %) |
| Height (m) | 1.69 (0.11) |
| Weight (kg) | 87.5 (16.9) |
| ASA: | |
| 0 | 11 (2.17 %) |
| 1 | 10 (1.98 %) |
| 2 | 401 (79.2 %) |
| 3 | 84 (16.6 %) |
| CCI | 2.77 (1.09) |
| BMI | 30.0 (4.70) |
| Elixhauser | 0.69 (0.89) |
| PreOp Coagulopathy | |
| No | 508 (99.6 %) |
| Yes | 2 (0.39 %) |
| Cardiovascular Disease | |
| No | 470 (92.2 %) |
| Yes | 40 (7.84 %) |
| Procedure: | |
| Primary bsTHA | 139 (27.3 %) |
| Primary bsTKA | 371 (72.7 %) |
| Op Time | 135 (35.0) |
| LOS | 2.59 (1.82) |
3.1. Full cohort blood loss and readmission information
Patients had a mean preoperative Hgb of 14.1 g/dL (SD 1.27), starting blood volume of 5012 mL (SD 925), postoperative Hgb of 10.1 g/dL (SD 1.19), delta Hgb of 3.97 g/dL (SD 1.13), and perioperative blood loss of 1403 mL (SD 439). Anemia was present preoperatively in 17.6 % of cases and anemia was present postoperatively in 97.3 % of cases (Table 2). TXA was utilized in 82.7 % of cases. In total, 19 patients (3.73 %) experienced 90-day readmission, with no patients needing transfusion during readmission (Table 2, Fig. 2).
Table 2.
Data regarding hemoglobin and 90-day readmission.
| Patient Factors | Patients (n = 510) |
|---|---|
| PreOp Hgb | 14.1 (1.27) |
| PreOp Anemia: | |
| No | 420 (82.4 %) |
| Yes | 90 (17.6 %) |
| Starting Blood Volume (mL) | 5012 (928) |
| PostOp Hgb | 10.1 (1.19) |
| Blood Loss Volume (mL) | 1403 (439) |
| PostOp Anemia: | |
| No | 14 (2.75 %) |
| Yes | 496 (97.3 %) |
| Delta Hgb | 3.97 (1.13) |
| TXA Used: | |
| No | 88 (17.3 %) |
| Yes | 422 (82.7 %) |
| PostOp Readmission: | |
| No | 491 (96.3 %) |
| Yes | 19 (3.73 %) |
| Readmit Timeline: | |
| No readmit | 491 (96.3 %) |
| Within 30 days | 11 (2.16 %) |
| Within 90 days | 19 (3.70 %) |
Fig. 2.
Reasons for readmission within 90 Days.
3.2. Demographic, blood loss, and readmission information for patients with CVD
In comparison to patients without CVD, individuals who had CVD had a higher age-adjusted CCI (3.21 vs. 2.73; p = 0.009), with no difference in age (63.5 vs. 62.0; p = 0.088) or the proportion of patients with coagulopathy (0.0 % vs. 0.43 %; p = 1.0) (Table 3).
Table 3.
Demographic information for patients based on cardiovascular disease status.
| Patient Characteristics |
No |
Yes |
P-Value |
|---|---|---|---|
| n = 470 | n = 40 | ||
| Age | 60.4 (8.52) | 62.8 (6.36) | 0.088 |
| Gender: | 0.306 | ||
| Male | 234 (49.8 %) | 16 (40.0 %) | |
| Female | 236 (50.2 %) | 24 (60.0 %) | |
| Height (m) | 1.69 (0.11) | 1.68 (0.12) | 0.595 |
| Weight (kg) | 87.6 (16.8) | 86.6 (17.8) | 0.660 |
| ASA: | 0.047 | ||
| 0 | 11 (2.36 %) | 0 (0.00 %) | |
| 1 | 10 (2.14 %) | 0 (0.00 %) | |
| 2 | 375 (80.3 %) | 26 (66.7 %) | |
| 3 | 71 (15.2 %) | 13 (33.3 %) | |
| CCI | 2.73 (1.10) | 3.21 (0.99) | 0.009 |
| BMI | 30.1 (4.70) | 29.7 (4.68) | 0.694 |
| Elixhauser | 0.66 (0.86) | 1.15 (1.14) | 0.002 |
| PreOp Coagulopathy | 1.000 | ||
| No | 468 (99.6 %) | 40 (100 %) | |
| Yes | 2 (0.43 %) | 0 (0.00 %) | |
| Procedure: | 0.882 | ||
| Primary bsTHA | 129 (27.4 %) | 10 (25.0 %) | |
| Primary bsTKA | 341 (72.6 %) | 30 (75.0 %) | |
| Op Time | 135 (34.9) | 129 (36.0) | 0.144 |
| LOS | 2.58 (1.87) | 2.67 (1.14) | 0.273 |
Patients diagnosed with CVD had an average preoperative Hgb of 13.8 g/dL (SD 1.39), starting blood volume of 4931 mL (SD 986), postoperative Hgb of 9.96 g/dL (SD 1.24), perioperative blood loss of 1357 mL (SD 431), and delta Hgb of 3.83 g/dL (SD 1.14), which was similar to patients who did not have CVD (Table 4). Anemia prior to surgery was found in 27.5 % of patients, while anemia after surgery was present in all patients, with no significant differences from patients not having CVD (Table 4). TXA was used in 75.0 % of cases, with no significant differences compared to patients without CVD (Table 4). Patients with CVD had a higher readmission rate compared to patients without CVD (12.5 % vs. 2.98 %; p = 0.012) (Table 4).
Table 4.
Data on hemoglobin and 90-day readmission data based on patient cardiovascular disease status.
| Patient Characteristics |
No |
Yes |
P Value |
|---|---|---|---|
| N = 470 | N = 40 | ||
| PreOp Hgb | 14.1 (1.26) | 13.8 (1.39) | 0.167 |
| PreOp Anemia: | 0.137 | ||
| No | 391 (83.2 %) | 29 (72.5 %) | |
| Yes | 79 (16.8 %) | 11 (27.5 %) | |
| Starting Blood Volume (mL) | 5018 (923) | 4931 (986) | 0.580 |
| PostOp Hgb | 10.1 (1.18) | 9.96 (1.24) | 0.417 |
| Blood Loss Volume (mL) | 1407 (439) | 1357 (431) | 0.544 |
| PostOp Anemia: | 0.615 | ||
| No | 14 (2.98 %) | 0 (0.00 %) | |
| Yes | 456 (97.0 %) | 40 (100 %) | |
| Delta Hgb | 3.98 (1.13) | 3.83 (1.14) | 0.478 |
| TXA Used: | 0.257 | ||
| No | 78 (16.6 %) | 10 (25.0 %) | |
| Yes | 392 (83.4 %) | 30 (75.0 %) | |
| PostOp Readmission: | 0.012 | ||
| No | 456 (97.0 %) | 35 (87.5 %) | |
| Yes | 14 (2.98 %) | 5 (12.5 %) | |
| Readmit Timeline: | 0.006 | ||
| No readmit | 456 (97.0 %) | 35 (87.5 %) | |
| Within 30 days | 7 (1.49 %) | 4 (10.0 %) | |
| Within 90 days | 7 (1.49 %) | 1 (2.50 %) | |
| Transfusion During Readmission: 0 | 470 (100 %) | 40 (100 %) | - |
3.3. Unadjusted AUCs for perioperative blood loss (mL) & Delta Hgb
When forecasting 90-day readmission utilizing delta Hgb for everyone who underwent primary simBTJA, a threshold of 4.1 g/dL had an AUC of 0.454 [0.322–0.587], a SEN of 0.473, and a SPEC of 0.56. (Table 5) (Fig. 3). In patients with CVD, a threshold of 4.9 g/dL had an AUC of 0.467 [0.367–0.568], a SEN of 0.250, and a SPEC of 0.797 (Table 5) (Fig. 3).
Table 5.
Measures of diagnostic accuracy for delta hemoglobin or blood loss volume predicting 90-day readmission, unadjusted.
| Variable | Cohort | Cutoff Value | SEN | SPEC | AUC (95 % CI) |
|---|---|---|---|---|---|
| Delta Hgb | Full Cohort | 4.100 | 0.473 | 0.56 | 0.454 (0.322 – 0.587) |
| Delta Hgb | CVD Cohort | 4.900 | 0.250 | 0.797 | 0.467 (0.367 – 0.568) |
| Blood Loss volume (mL) | Full | 1144.00 | 0.842 | 0.297 | 0.453 (0.336 – 0.57) |
| Blood Loss volume (mL) | CVD | 1144.00 | 1.00 | 0.400 | 0.611 (0.365 – 0.858) |
Fig. 3.
Unadjusted receiver operating characteristic curve analysis based on delta hemoglobin or blood loss in all patients or patients with cardiovascular disease.
When developing ROC curves to predict 90-day readmission based on perioperative blood loss volume (mL) for individuals having primary simBTJA, a threshold of 1144 mL had an AUC of 0.453 [0.336–0.57], a SEN of 0.842, and a SPEC of 0.297 (Table 5) (Fig. 3). In patients with CVD, a threshold of 1144 mL had an AUC of 0.611 [0.365–0.858], a SEN of 1.00, and a SPEC of 0.400 (Table 5) (Fig. 3).
3.4. Adjusted AUCs for perioperative blood loss (mL) & Delta Hgb
When predicting 90-day readmission based on delta Hgb that was adjusted for preoperative Hgb, or ROC curves to predict 90-day readmission based on perioperative blood loss that was adjusted for stating blood volume, the 95 % confidence interval (CI) included 0.500 for all patients and only patients with CVD, indicating the thresholds had poor diagnostic accuracy (Table 6) (Fig. 4).
Table 6.
Measures of diagnostic accuracy for delta hemoglobin or blood loss volume predicting 90-day readmission, adjusted for preoperative Hgb levels or total blood volume.
| Variable | Cohort | SEN | SPEC | AUC (95 % CI) |
|---|---|---|---|---|
| Delta Hemoglobin | Full Cohort | 0.473 | 0.718 | 0.571 (0.424 – 0.718) |
| Delta Hemoglobin | CVD Cohort | 0.800 | 0.514 | 0.514 (0.388 – 0.926) |
| Blood Loss volume (mL) | Full | 0.894 | 0.364 | 0.569 (0.453 – 0.686) |
| Blood Loss volume (mL) | CVD | 0.600 | 0.771 | 0.663 (0.356 – 0.969) |
*Abbreviations: SEN = sensitivity; SPEC = specificity; AUC = area under the curve; CI = confidence interval; mL = milliliters.
Fig. 4.
Adjusted receiver operating characteristic curve analysis based on delta hemoglobin or blood loss in all patients or patients with cardiovascular disease.
4. Discussion
Readmission following TJA can have devastating consequences for patients and healthcare teams, with additional time and resources needed to implement care. This may also lead to potential compromise of payment bundles for physicians and hospitals.20 Declining inflation-adjusted reimbursement for arthroplasty surgeons further compounds this,21 making it vital to limit readmission after surgery. While the results for studies evaluating safety of primary simBTJA are varied in the literature,22,23 this surgery can be a cost-effective intervention if conducted safely in select patients.24 Despite appropriate patient selection, high rates of postoperative transfusion still exist.5
Surgeons may believe patients need to be transfused postoperatively if Hgb has decreased significantly from their preoperative levels, even if it has not fallen to the transfusion threshold. Additionally, surgeons may fear that patients discharged with large delta Hgb values may have a higher odds for readmission. The findings of this study provides evidence that individuals having primary simBTJA who were not transfused perioperatively can be safely discharged with no elevated risk of 90-day readmission if their Hgb is 7 g/dL or higher, regardless of their delta Hgb or perioperative blood loss. This can provide surgeons reassurance that physiological compensation occurs adequately in these patients, despite large delta Hgb or blood loss amounts.
This study found that individuals who possess CVD have an elevated 90-day readmission rate, which is consistent with previous studies25,26 However, when constructing a ROC curve evaluating various thresholds for delta Hgb and perioperative blood loss in patients with CVD, there was no threshold delta Hgb or perioperative blood loss amount predictive of 90 day readmission. Similar to the previously mentioned reason, the use of TXA and other blood conservation strategies may be contributing to this. Zak et al. found that in patients who had CVD, utilizing TXA did not correlate with adverse effects in TJA patients.27 Those results, in conjunction with this study, suggest that TXA may be effectively used in patients with CVD undergoing primary simBTJA. Additionally, further study needs to be conducted to evaluate why patients with CVD have an increased readmission rate, and interventions need to be developed to mitigate that.
There are notable strengths of this study, which include a sizeable cohort compared to other studies evaluating simBTJA, along with the utilization of a nurse navigator, allowing us to efficiently collect complication data. There are many limitations of this study, which include that use of Hgb values closest to a patient's discharge, which may not be the most accurate Hgb value postoperatively. The median LOS in this study was 2 days, while previous studies have established the lowest Hgb value occurs on POD 4.11 However, the Hgb values taken on POD 1 and 2 are the values used to make the majority of clinical decisions such as suitability for discharge, rendering the results applicable to daily practice. Additionally, the retrospective cohort style of this study can be associated with various biases. Lastly, this study does not apply to individuals transfused during their surgical procedure admission, and it cannot be applied to patients discharged to skilled nursing facilities or rehabilitation units. Since individuals discharged to a subacute facility are more prone to readmission, inclusion of those patients would potentially bias the results.
5. Conclusions
This study revealed that patients undergoing primary simBTJA who are managed with standardized blood conservation protocols and do not receive transfusions during their hospital admission can be safely discharged with no elevated 90-day readmission risk if their postoperative Hgb is greater than 7 g/dL, regardless of their delta Hgb or amount of perioperative blood loss.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
- 1.Zhang Q, Huang K, Yin S, et al. Hypotensive anesthesia combined with tranexamic acid reduces perioperative blood loss in simultaneous bilateral total hip arthroplasty: a retrospective cohort study. Orthop Surg. Published online February 9, 2022:os.13200. doi:10.1111/os.13200. [DOI] [PMC free article] [PubMed]
- 2.Karaaslan F., Karaoğlu S., Mermerkaya M.U., Baktir A. Reducing blood loss in simultaneous bilateral total knee arthroplasty: combined intravenous–intra-articular tranexamic acid administration. A prospective randomized controlled trial. Knee. 2015;22(2):131–135. doi: 10.1016/j.knee.2014.12.002. [DOI] [PubMed] [Google Scholar]
- 3.Romagnoli S., Zacchetti S., Perazzo P., Verde F., Banfi G., Viganò M. Simultaneous bilateral total hip arthroplasties do not lead to higher complication or allogeneic transfusion rates compared to unilateral procedures. Int Orthop. 2013;37(11):2125–2130. doi: 10.1007/s00264-013-2015-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Morcos M.W., Hart A., Antoniou J., Huk O.L., Zukor D.J., Bergeron S.G. No difference in major complication and readmission rates following simultaneous bilateral vs unilateral total hip arthroplasty. J Arthroplasty. 2018;33(8):2541–2545. doi: 10.1016/j.arth.2018.03.050. [DOI] [PubMed] [Google Scholar]
- 5.Chalmers B.P., Mishu M., Chiu Y fen, et al. Simultaneous bilateral primary total knee arthroplasty with TXA and restrictive transfusion protocols: still a 1 in 5 risk of allogeneic transfusion. J Arthroplasty. 2021;36(4):1318–1321. doi: 10.1016/j.arth.2020.10.042. [DOI] [PubMed] [Google Scholar]
- 6.Abdelaal M.S., Calem D., Sherman M.B., Sharkey P.F. Short interval staged bilateral total knee arthroplasty: safety compared to simultaneous and later staged bilateral total knee arthroplasty. J Arthroplasty. 2021;36(12):3901–3908. doi: 10.1016/j.arth.2021.08.030. [DOI] [PubMed] [Google Scholar]
- 7.Delaney M., Wendel S., Bercovitz R.S., et al. Transfusion reactions: prevention, diagnosis, and treatment. Lancet. 2016;388(10061):2825–2836. doi: 10.1016/S0140-6736(15)01313-6. [DOI] [PubMed] [Google Scholar]
- 8.Owens J., Otero J.E., Noiseux N.O., Springer B.D., Martin J.R. Risk factors for post-operative blood transfusion following total knee arthroplasty. Iowa Orthop J. 2020;40(1):69–73. [PMC free article] [PubMed] [Google Scholar]
- 9.Carson J.L., Guyatt G., Heddle N.M., et al. Clinical practice guidelines from the AABB: red blood cell transfusion thresholds and storage. JAMA. 2016;316(19):2025. doi: 10.1001/jama.2016.9185. [DOI] [PubMed] [Google Scholar]
- 10.Mueller M.M., Van Remoortel H., Meybohm P., et al. Patient blood management: recommendations from the 2018 frankfurt consensus conference. JAMA. 2019;321(10):983. doi: 10.1001/jama.2019.0554. [DOI] [PubMed] [Google Scholar]
- 11.Chen Z.Y., Wu H.Z., Zhu P., Feng X.B. Postoperative changes in hemoglobin and hematocrit in patients undergoing primary total hip and knee arthroplasty. Chinese Med J. 2015;128(14):1977–1979. doi: 10.4103/0366-6999.160620. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Cuschieri S. The STROBE guidelines. Saudi J Anaesth. 2019;13(5):31. doi: 10.4103/sja.SJA_543_18. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Sharma R., Sharma S. StatPearls. StatPearls Publishing; 2022. Physiology, blood volume.http://www.ncbi.nlm.nih.gov/books/NBK526077/ [PubMed] [Google Scholar]
- 14.Gao F.Q., Li Z.J., Zhang K., Sun W., Zhang H. Four methods for calculating blood-loss after total knee arthroplasty. Chinese Med J. 2015;128(21):2856–2860. doi: 10.4103/0366-6999.168041. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Phillips J.L.H., Rondon A.J., Vannello C., Fillingham Y.A., Austin M.S., Courtney P.M. A nurse navigator program is effective in reducing episode-of-care costs following primary hip and knee arthroplasty. J Arthroplasty. 2019;34(8):1557–1562. doi: 10.1016/j.arth.2019.04.062. [DOI] [PubMed] [Google Scholar]
- 16.Freeman A.M., Rai M., Morando D.W. StatPearls. StatPearls Publishing; 2021. Anemia screening.http://www.ncbi.nlm.nih.gov/books/NBK499905/ [PubMed] [Google Scholar]
- 17.Inayat K., Danish N., Hassan L. Symptoms of menopause in peri and postmenopausal women and their attitude towards them. J Ayub Med Coll Abbottabad. 2017;29(3):477–480. [PubMed] [Google Scholar]
- 18.Cardiovascular diseases (CVDs) https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds Published online June 11, 2021.
- 19.Mandrekar J.N. Receiver operating characteristic curve in diagnostic test assessment. J Thorac Oncol. 2010;5(9):1315–1316. doi: 10.1097/JTO.0b013e3181ec173d. [DOI] [PubMed] [Google Scholar]
- 20.Sullivan R., Jarvis L.D., O'Gara T., Langfitt M., Emory C. Bundled payments in total joint arthroplasty and spine surgery. Curr Rev Musculoskelet Med. 2017;10(2):218–223. doi: 10.1007/s12178-017-9405-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Nayar S.K., MacMahon A., Mikula J.D., Greenberg M., Barry K., Rao S.S. Free falling: declining inflation-adjusted payment for arthroplasty surgeons. J Arthroplasty. 2021;36(3):795–800. doi: 10.1016/j.arth.2020.09.047. [DOI] [PubMed] [Google Scholar]
- 22.Makaram N.S., Roberts S.B., Macpherson G.J. Simultaneous bilateral total knee arthroplasty is associated with shorter length of stay but increased mortality compared with staged bilateral total knee arthroplasty: a systematic review and meta-analysis. J Arthroplasty. 2021;36(6):2227–2238. doi: 10.1016/j.arth.2021.01.045. [DOI] [PubMed] [Google Scholar]
- 23.Liu L., Liu H., Zhang H., Song J., Zhang L. Bilateral total knee arthroplasty: simultaneous or staged? A systematic review and meta-analysis. Medicine. 2019;98(22) doi: 10.1097/MD.0000000000015931. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Hou J.F., Hu C., Zhang Y., et al. Cost analysis of staged versus simultaneous bilateral total knee and hip arthroplasty using a propensity score matching. BMJ Open. 2021;11(3) doi: 10.1136/bmjopen-2020-041147. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Ali A.M., Loeffler M.D., Aylin P., Bottle A. Factors associated with 30-day readmission after primary total hip arthroplasty: analysis of 514 455 procedures in the UK national Health service. JAMA Surg. 2017;152(12) doi: 10.1001/jamasurg.2017.3949. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Mahajan S.M., Nguyen C., Bui J., Kunde E., Abbott B.T., Mahajan A.S. Risk factors for readmission after knee arthroplasty based on predictive models: a systematic review. Arthroplasty Today. 2020;6(3):390–404. doi: 10.1016/j.artd.2020.04.017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Zak S.G., Tang A., Sharan M., Waren D., Rozell J.C., Schwarzkopf R. Tranexamic acid is safe in patients with a history of coronary artery disease undergoing total joint arthroplasty. J Bone Joint Surg. 2021;103(10):900–904. doi: 10.2106/JBJS.20.01226. [DOI] [PubMed] [Google Scholar]