Abstract
Background
The current Canadian guidelines endorse the use of MgSO4 for treatment of eclampsia and for prophylaxis in severe preeclampsia. Our study aimed to audit our institution’s compliance regarding these guidelines.
Methods
We conducted a retrospective study to evaluate MgSO4 use in: all our cases of eclampsia since 2002, 50 cases of severe preeclampsia, and 50 cases of non-severe preeclampsia.
Results
Sixty-five cases of preeclampsia were analyzed after initial chart review. A high rate of preeclampsia severity misdiagnosis was observed (35%, 23/65). Only 69% (25/36) of the patients correctly diagnosed with severe preeclampsia received MgSO4; after diagnosis correction, 42% (25/59) of the patients with severe preeclampsia received the medication. Of our eight cases of eclampsia, none of the patients received MgSO4 before the seizure (although three had clear indications).
Conclusion
Given the importance of prophylactic MgSO4 use in preventing eclampsia, we have implemented informative measures aimed at rapidly achieving complete compliance with the national guidelines.
Keywords: Severe preeclampsia, non-severe preeclampsia, eclampsia, magnesium sulfate
Background
With preeclampsia complicating 2–8% of pregnancies and eclampsia occurring in 4–6 per 10,000 live births,1 these hypertensive disorders of pregnancy remain among the principal causes of maternal and perinatal morbidity and mortality. In an attempt to provide a clear approach to the diagnosis, evaluation, and management of the different hypertensive disorders of pregnancy, the Society of Obstetricians and Gynaecologists of Canada (SOGC) endorsed a series of clinical practice guidelines (hereafter “the guidelines”) based on the best available scientific evidence.2
The guidelines describe preeclampsia as a hypertensive disorder of pregnancy characterized by the presence of proteinuria or the presence of one or more “adverse conditions” (full list of adverse conditions in Magee et al. 2008). Severe preeclampsia is further defined as pre-eclampsia with: onset before 34 weeks’ gestation, heavy proteinuria, or the presence of one or more adverse conditions.2 A small proportion of patients with preeclampsia go on to develop eclampsia (0.5%–3%),3,4 which has been associated with persistent visual and neurological sequelae that may carry long-term consequences for the mother.5–8 Forty percent of deaths from eclampsia are thought to be preventable.9
The guidelines recommend the use of magnesium sulfate (MgSO4) for prophylaxis in patients with severe preeclampsia (I-A10,11) and for the treatment of eclampsia (I-A).2 In developed countries, MgSO4 administration for non-severe preeclampsia may also be considered (I-B).2
Given the demonstrated importance of MgSO4 use in preventing and treating eclampsia3,12 and a perceived lack of uniformity in our institution’s use of MgSO4, we felt it was important to undertake an audit of our practices. The primary objective of this study was to evaluate if the use of MgSO4 for treating severe preeclampsia and eclampsia at the Centre Hospitalier Universitaire de Sherbrooke (CHUS) conforms to the current Canadian guidelines. In the event of imperfect compliance, we aimed to identify the criteria influencing a clinician’s decision to administer or withhold MgSO4 for the treatment of severe preeclampsia.
Methods
This is a descriptive, retrospective study based on the information provided in patient charts obtained from the CIRESSS (Centre informatisé de recherche évaluative en services et soins de santé) database, where hospital summary sheets are maintained. The study protocol was approved by our institution’s Research Ethics Board.
Sample
The following charts were requested from the CIRESSS database: 50 most recent consecutive cases of non-severe preeclampsia between 1 January 2009 and 22 May 2010; 50 most recent consecutive cases of severe preeclampsia between 1 January 2009 and 22 May 2010. We also requested all cases of eclampsia from 1 January 2002 (publication of the MAGPIE trial3) to 31 January 2012 to specifically evaluate the current practices of clinicians who are faced with this rare occurrence at our institution. This sample size was used based on the resources available for the extensive chart review needed to attain the primary objective. We excluded “preeclampsia superimposed on pre-existing hypertension” to reduce the impact of confounding factors in the management of these patients whose diagnosis and evaluation of severity are especially difficult. Patient characteristics, presence of adverse conditions (10 of the 18 defined by the guidelines2), and management modalities were recorded using chart review. Preeclampsia severity diagnoses were verified carefully by the research team to identify cases of severe preeclampsia initially misdiagnosed as non-severe, e.g. cases in which the presence of one or more adverse conditions was recorded in the chart, yet the patient was diagnosed with non-severe preeclampsia. Current practice was then compared to the guidelines for MgSO4 use in eclampsia and preeclampsia management.
Statistical analysis
Chi-square and Fisher’s exact tests were used to identify the factors influencing a clinician’s decision to administer or withhold prophylactic MgSO4 by comparing patients with severe preeclampsia, initially accurately diagnosed, that did and did not receive MgSO4. To determine what factors most influenced clinicians’ preeclampsia severity diagnoses, we used Chi-square and Fisher’s exact tests to compare the characteristics of patients with severe preeclampsia with correct and incorrect initial diagnoses. A binary logistic regression analysis with backward stepwise model selection was then used to further identify factors associated with preeclampsia severity diagnoses.
Results
Preeclampsia
Of the 100 cases available for review, 34 were rejected for presenting hypertensive disorders without preeclampsia, and one file was rejected due to a classification error. Figure 1 depicts the classification of the remaining 65 files according to preeclampsia severity and highlights the high rate of preeclampsia severity misdiagnosis; 23 severe cases were incorrectly diagnosed as non-severe (misdiagnosis rate of 35%). After correcting these diagnoses, 59/65 (91%) of the preeclampsia cases met the guidelines’ criteria for diagnosis as “severe.” Table 1 provides additional information about the patients including symptoms and management.
Figure 1.
Patient selection and classification related to the audit of preeclampsia management.
Table 1.
Patient characteristics for the cases of preeclampsia (non-severe and severe; after diagnosis correction) and eclampsia used in the audit.
| Patient characteristics | Non-severe preeclampsia (%) | Severe preeclampsia (%) | Eclampsia (%) |
|---|---|---|---|
| Number of cases (n) | 6(100) | 59(100) | 8(100) |
| Postpartum eclampsia | – | – | 5(63) |
| Primiparous | 2(33) | 53(90) | 2(25) |
| Age group (years) | |||
| 16–24 | 1(17) | 14(24) | 2(25) |
| 25–34 | 4(67) | 37(63) | 6(75) |
| 35–45 | 1(17) | 8(14) | – |
| Adverse conditionsa | |||
| Persistent new/unusual headaches | – | 29(49) | 6(75) |
| Visual disturbances | – | 16(27) | 3(38) |
| Persistent abdominal/right upper quadrant pain | – | 15(25) | 3(38) |
| Severe hypertension | – | 40(68) | 7(88) |
| Elevated serum creatinine | – | 17(29) | 5(63) |
| Elevated liver enzymes | – | 31(53) | 3(38) |
| Thrombocytopenia | – | 12(20) | 3(38) |
| Intrauterine growth restriction | – | 5(9) | – |
| Absent/reversed end-diastolic flow in umbilical artery | – | 4(7) | – |
| Other conditions | |||
| Proteinuria | 5(83) | 48(81) | 5(63) |
| Hyperreflexia | – | 30(51) | 6(75) |
| Hyponatremia | – | 2(3) | 4(50) |
| Evaluation | |||
| Cerebral imaging (CT scan) | – | 1(2) | 6(75) |
| Magnesium blood monitoring | – | 6(10) | 6(75) |
| Management | |||
| Prophylactic MgSO4 administration | – | 25(42) | – |
| Posteclampsia MgSO4 administration | NA | NA | 7(88) |
| Use of calcium gluconate | – | – | – |
| Antihypertensive medication | – | 32(54) | 7(88) |
| Concurrent SOGC symptomsb | |||
| 0 | 6(100) | 18(31) | 1(13) |
| 1 | – | 25(42) | 2(25) |
| 2 | – | 13(22) | 5(63) |
| 3 | – | 3(5) | – |
| Concurrent SOGC signsc | |||
| 0 | 6(100) | 7(12) | – |
| 1 | – | 17(29) | 1(13) |
| 2 | – | 19(32) | 2(25) |
| 3 | – | 10(17) | 1(13) |
| 4 | – | 6(10) | 2(25) |
| 5 | – | – | 2(25) |
As defined by the Clinical Practice Guidelines endorsed by the Society of Obstetricians and Gynaecologists of Canada.2
Includes: persistent new/unusual headaches, visual disturbances, and persistent abdominal/right upper quadrant pain.
Includes: eclampsia, severe hypertension, elevated creatinine, elevated liver enzymes, thrombocytopenia, intrauterine growth restriction, and absent/reversed end-diastolic flow in umbilical artery.
Data are presented as: number of patients (%).
NA: not applicable; SOGC: Society of Obstetricians and Gynaecologists of Canada.
Among the 59 patients meeting the criteria for severe preeclampsia and in whom prophylactic MgSO4 would have been indicated, 25 (42%) received MgSO4. All the patients who received the medication were among the 36 cases initially correctly diagnosed as “severe” (25/36 (69%); Figure 1). No other patients received MgSO4 prophylactically and none had contraindications related to MgSO4.
Table 2 compares the characteristics of women diagnosed with severe preeclampsia, exclusively those initially correctly diagnosed as such (n = 36), who received MgSO4 to those that did not. None of the comparisons yielded statistically significant differences.
Table 2.
Identification of patient characteristics involved in the decision to administer MgSO4 prophylactically in patients correctly diagnosed with severe preeclampsia.
| Patient characteristics | Received prophylactic MgSO4 (%) | Did not receive prophylactic MgSO4 (%) | p value |
|---|---|---|---|
| Subset of patients: patients correctly diagnosed with severe preeclampsia (n = 36) | |||
| Number of cases | 25(100) | 11(100) | – |
| Primiparous | 24(96) | 9(82) | 0.216 |
| Age group (years) | |||
| 16–24 | 3(12) | 4(36) | 0.190 |
| 25–34 | 18(72) | 7(64) | |
| 35–45 | 4(16) | – | |
| Adverse conditionsa | |||
| Persistent new/unusual headaches | 14(56) | 5(45) | 0.559 |
| Visual disturbances | 9(36) | 2(18) | 0.439 |
| Persistent abdominal/right upper quadrant pain | 7(28) | 3(27) | 1.000 |
| Severe hypertension | 20(80) | 10(91) | 0.643 |
| Elevated serum creatinine | 9(36) | 5(45) | 0.716 |
| Elevated liver enzymes | 15(60) | 6(55) | 1.000 |
| Thrombocytopenia | 8(32) | 2(18) | 0.688 |
| Intrauterine growth restriction | 3(12) | – | 0.538 |
| Absent/reversed end-diastolic flow in umbilical artery | 1(4) | – | 1.000 |
| Other conditions | |||
| Proteinuria | 19(76) | 10(91) | 0.400 |
| Hyperreflexia | 17(68) | 6(55) | 0.475 |
| Hyponatremia | 2(8) | – | 1.000 |
| Management | |||
| Antihypertensive medication | 19(76) | 7(64) | 0.454 |
| Concurrent SOGC symptomsb | |||
| 0 | 5(20) | 5(45) | 0.461 |
| 1 | 12(48) | 3(27) | |
| 2 | 6(24) | 2(18) | |
| 3 | 2(8) | 1(9) | |
| Concurrent SOGC signsc | |||
| 0 | 2(8) | – | 0.210 |
| 1 | 5(20) | 4(36) | |
| 2 | 8(32) | 2(18) | |
| 3 | 5(20) | 5(45) | |
| 4 | 5(20) | – | |
As defined by the Clinical Practice Guidelines endorsed by the Society of Obstetricians and Gynaecologists of Canada.2
Includes: persistent new/unusual headaches, visual disturbances, and persistent abdominal/right upper quadrant pain.
Includes: eclampsia, severe hypertension, elevated creatinine, elevated liver enzymes, thrombocytopenia, intrauterine growth restriction, and absent/reversed end-diastolic flow in umbilical artery.
Data are presented as: number of patients (%). p values correspond to Chi-square or Fisher’s exact tests. Bold characters highlight significant results.
SOGC: Society of Obstetricians and Gynaecologists of Canada.
Univariate comparison of the characteristics of patients correctly and incorrectly diagnosed with severe preeclampsia revealed that severe hypertension (and use of antihypertensive medication), elevated creatinine levels, and hyperreflexia were significantly associated with an accurate diagnosis (Table 3). Furthermore, as the number of concurrent signs included in the guidelines as “adverse conditions” increased, the proportion of patients correctly diagnosed as severely preeclamptic also increased (p = 0.011). A similar pattern was tested for in concurrent symptoms identified as adverse conditions, but did not reach statistical significance (p = 0.676).
Table 3.
Identification of patient characteristics involved in the diagnosis of preeclampsia severity.
| Patient characteristics | Severe preeclampsia correctly diagnosed (%) | Severe preeclampsia incorrectly diagnosed (%) | p value |
|---|---|---|---|
| Subset of patients: all severe preeclampsia cases (n = 59) | |||
| Number of cases | 36(100) | 23(100) | – |
| Primiparous | 33(92) | 20(87) | 0.669 |
| Age group (years) | |||
| 16–24 | 7(19) | 7(30) | 0.425 |
| 25–34 | 25(69) | 12(52) | |
| 35–45 | 4(11) | 4(17) | |
| Adverse conditionsa | |||
| Persistent new/unusual headaches | 19(53) | 10(43) | 0.486 |
| Visual disturbances | 11(31) | 5(22) | 0.458 |
| Persistent abdominal/right upper quadrant pain | 10(28) | 5(22) | 0.603 |
| Severe hypertension | 30(83) | 10(43) | 0.001 |
| Elevated serum creatinine | 14(39) | 3(13) | 0.033 |
| Elevated liver enzymes | 21(58) | 10(43) | 0.265 |
| Thrombocytopenia | 10(28) | 2(9) | 0.103 |
| Intrauterine growth restriction | 3(8) | 2(9) | 1.000 |
| Absent/reversed end-diastolic flow in umbilical artery | 1(3) | 3(13) | 0.289 |
| Other conditions | |||
| Proteinuria | 29(81) | 19(83) | 1.000 |
| Hyperreflexia | 23(64) | 7(30) | 0.012 |
| Hyponatremia | 2(6) | – | 0.250 |
| Management | |||
| Antihypertensive medication | 26(72) | 6(26) | 0.001 |
| Concurrent SOGC symptomsb | |||
| 0 | 10(28) | 8(35) | 0.676 |
| 1 | 15(42) | 10(43) | |
| 2 | 8(22) | 5(22) | |
| 3 | 3(8) | – | |
| Concurrent SOGC signsc | |||
| 0 | 2(6) | 5(22) | 0.011 |
| 1 | 9(25) | 8(35) | |
| 2 | 10(28) | 9(39) | |
| 3 | 10(28) | – | |
| 4 | 5(14) | 1(4) | |
As defined by the Clinical Practice Guidelines endorsed by the Society of Obstetricians and Gynaecologists of Canada.2
Includes: persistent new/unusual headaches, visual disturbances, and persistent abdominal/right upper quadrant pain.
Includes: eclampsia, severe hypertension, elevated creatinine, elevated liver enzymes, thrombocytopenia, intrauterine growth restriction, and absent/reversed end-diastolic flow in umbilical artery.
Data are presented as: number of patients (%). p values correspond to Chi-square or Fisher’s exact tests. Bold characters highlight significant results.
SOGC: Society of Obstetricians and Gynaecologists of Canada.
Among the patient characteristics presented in Table 3, the final logistic regression model retained severe hypertension and thrombocytopenia as factors contributing significantly to an accurate diagnosis of “severe preeclampsia”; elevated serum creatinine was retained as well, though did not quite attain statistical significance (see Table 4 for significance, odds ratios, and 95% confidence intervals).
Table 4.
Variables associated with an accurate diagnosis of preeclampsia severity as identified by binary logistic regression analysis using backward stepwise model selection.
| Variables | p value | Odds ratio | 95% confidence interval |
|---|---|---|---|
| Severe hypertension | 0.004 | 7.411 | 1.885–29.136 |
| Elevated serum creatinine | 0.064 | 4.391 | 0.916–21.060 |
| Thrombocytopenia | 0.040 | 7.446 | 1.095–50.629 |
Eclampsia
Eight cases of eclampsia were attended to at the CHUS in the selected timeframe (Table 1). None of the patients were being treated prophylactically with MgSO4 at the time of the seizure. Seven patients were treated with MgSO4 after seizure. The remaining patient, whose diagnosis was uncertain at the time, did not receive anticonvulsants, but was subsequently diagnosed with eclampsia by exclusion of other diagnoses. Three of the eight eclampsia cases presented to the hospital during or just after a seizure. Three other cases presented episodes of severe hypertension or other adverse conditions indicative of severe preeclampsia before the seizure.
Discussion
Our report reveals an underutilization of MgSO4 prophylactically in women with severe preeclampsia despite what is clearly recommended in the guidelines. A high proportion of erroneous diagnoses is likely to be partly responsible, but even among women correctly diagnosed with severe preeclampsia, only 69% received MgSO4. While the lack of significant associations between specific patient characteristics and MgSO4 administration may result from our limited sample size, it may also reflect the absence of a clearly defined protocol for MgSO4 use in our institution – one of the motivating factors for this audit. Among women having received MgSO4, no calcium gluconate was required, suggesting that MgSO4 was used appropriately with no severe negative side-effects.
In addition, our audit revealed considerable inconsistency in the accurate diagnosis of severe preeclampsia. This seems to be the result of clinicians not having considered all the adverse conditions presented in the guidelines as warranting diagnosis as “severe.” The logistic regression analysis identified only severe hypertension and two abnormal laboratory tests as signs consistently relied on by clinicians to accurately diagnose severe preeclampsia. If the guidelines had been fully implemented, all of the adverse conditions considered in the analysis would have shown an association with an accurate diagnosis.
As per guidelines recommendations, all patients with eclampsia received MgSO4 as treatment when a clear diagnosis was established. However, we estimate that of the five patients that were in the hospital prior to starting convulsions, eclampsia could have been prevented in three of these patients by administering prophylactic MgSO4, given that adverse conditions were present before the seizure. In a Canadian study, the incidence of eclampsia was shown to have declined by 50% between 2003 and 2010.13 While improved antenatal care, premature delivery in cases of preeclampsia, and improved maternal and neonatal intensive care are believed to have contributed to this decline, the authors presume that the main factor responsible was the increased prophylactic use of MgSO4 in women with severe preeclampsia.13
Our study was limited statistically as a result of 35% of cases being rejected outright due to the extraction of patient files classified under code O13 of the 2010 International Classification of Diseases (uncomplicated gestational hypertension). In combination with the high misdiagnosis rate, it was difficult to pursue additional statistical avenues; however, it is clear that our use of MgSO4 in patients with severe preeclampsia was suboptimal.
Conclusion
In order to improve our personnel’s ability to accurately diagnose preeclampsia severity and increase their use of MgSO4 when appropriate, a MgSO4 protocol and informative poster were developed emphasizing the guidelines’ criteria for severity, as well as providing recommendations for using MgSO4 to treat severe preeclampsia in the maternity ward. Also, a similar analysis will be repeated after an adjustment period to see whether the measures undertaken have a positive impact on diagnostic accuracy and MgSO4 prescription when indicated.
Acknowledgements
The authors would like to thank our institution’s “Quality of Care in Obstetrics Committee” for their help with the protocol and evaluation grid, Marie-Pierre Garant for statistical analysis, Ariane Breton from the archive Info-Centre, Jessica Pilotte for clerical support, and John Davison for translation. A special thanks to Jennifer Chambers for her considerable help with editing the final manuscript.
Declaration of conflicting interests
PG, AQ, YAB, and NS have no conflicts of interests to disclose. Sauvé is member of the FRQS-funded Étienne-Le Bel Clinical Research Center.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Ethical approval
The Research Ethics Board of the Centre Hospitalier Universitaire de Sherbrooke approved this study.
Guarantor
NS.
Contributorship
PG, AQ, and NS researched the literature, conceived the study and obtained ethical approval. PG, AQ, YAB, and NS were involved in protocol development. PG and AQ reviewed all charts and wrote the first draft of the manuscript. All authors reviewed and edited the manuscript and approved its final version.
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