A More Selective vs a Standard Risk-Stratified, Heparin-Based, Obstetric Thromboprophylaxis Protocol.

Importance: In 2016, our institution adopted a pregnancy-related venous thromboembolism (VTE) prophylaxis protocol based on American College of Obstetricians and Gynecologists guidelines that recommended postpartum heparin-based chemoprophylaxis (enoxaparin) based on a risk-stratified algorithm. In response to increased wound hematomas without significant reduction in VTE using this protocol, a more selective risk-stratified approach was adopted in 2021. Objective: To evaluate outcomes of the more selective risk-stratified approach to heparin-based obstetric thromboprophylaxis (enoxaparin) protocol. Design, Setting, and Participants: Retrospective observational study of 17 489 patients who delivered at a single tertiary care center in the southeast US between January 1, 2016, and December 31, 2018 (original protocol), and between December 1, 2021, and May 31, 2023 (more selective protocol). Patients receiving outpatient anticoagulation for active VTE or high VTE risk during pregnancy were excluded. Exposure: Standard risk-stratified and more selective postpartum VTE chemoprophylaxis protocols. Main Outcomes and Measures: The primary outcome was clinical diagnosis of wound hematoma up to 6 weeks pos tpartum. The secondary outcome was new diagnosis of VTE up to 6 weeks post partum. We compared baseline characteristics and outcomes between groups and estimated adjusted odds ratios with 95% CIs of primary and secondary outcomes using the original protocol group as reference. Results: Of 17 489 patients included in the analysis, 12 430 (71%) were in the original protocol group and 5029 (29%) were in the more selective group. Rates of chemoprophylaxis decreased from 16% (original protocol) to 8% (more selective protocol). Patients in the more selective group were more likely to be older, be married, and have obesity or other comorbidities (hypertension, diabetes, cardiac disease). Compared with the original protocol, the more selective protocol was associated with a decrease in any wound hematoma (0.7% vs 0.3%; adjusted odds ratio [aOR], 0.38; 95% CI, 0.21-0.67), specifically due to a lower rate of superficial wound hematomas (0.6% vs 0.3%; aOR, 0.43; 95% CI, 0.24-0.75). There was no significant increase in VTE or individual types of VTE (0.1% vs 0.1%; aOR, 0.40; 95% CI, 0.12-1.36). Conclusions and Relevance: A more selective risk-stratified approach to an enoxaparin thromboprophylaxis protocol for VTE was associated with decreased rates of wound hematomas without increased rates of postpartum VTE.

Impact of the p-Value Threshold on Interpretation of Trial Outcomes in Obstetrics and Gynecology.

OBJECTIVE: Randomized controlled trials (RCTs) are considered the highest level of evidence to inform clinical practice. However, the reproducibility crisis has raised concerns about the scientific rigor of published RCT findings. Some advocate for a lower p-value threshold. We aimed to review published OB/Gyn topical RCTs in three representative OB/Gyn journals and three high impact non-OB/Gyn journals to determine if their interpretations would change with adoption of a p-value threshold for significance of 0.005. Secondarily, we evaluated if there were differences in methodologic characteristics between those that did and did not lose significance. STUDY DESIGN: A manual search was performed to identify all OB/Gyn RCTs published in the selected journals between July 2017 and June 2019. Data were collected on primary outcome(s), methodology, and p-values. We determined the proportion of primary outcomes that would remain statistically significant with adoption of a p-value significance threshold of 0.005 versus be reinterpreted as "suggestive" (defined as p-value between 0.005 and 0.05). Chi-square or Fisher's exact test were used to compare study characteristics. RESULTS: Overall, 202 RCTs met inclusion criteria; 52% in obstetrics and 48% in gynecology. Of 90 studies considered significant with p <0.05 at the time of publication, 54.4% (n = 49) would maintain significant (p < 0.005), while 45.6% (n = 41) would become suggestive using the lower threshold. Most RCTs utilized a single (90.1%) versus composite (8.9%) primary outcome type, used an intent-to-treat analysis (73.3%), and studied a drug intervention (46.5%). Methodologically, 23.7% did not prespecify analysis type, 28.2% did not meet the pre-determined sample size, and 9.4% did not report an a priori sample size calculation. Studies maintaining significance were more likely to be international and report a funding source. CONCLUSION: Adopting a p-value significance threshold of 0.005 would require reinterpretation of almost half of RCT results in the OB/Gyn literature. Highly variable methodological quality was identified. KEY POINTS: · New p-value threshold results in reinterpretation of nearly half of RCT results in OB/Gyn literature.. · Highly variable methodological quality was identified.. · Reduced use of binary interpretations of significance is necessary..