Trends in Venous Thromboembolism and Associated Risk Factors During Delivery Hospitalizations From 2000 to 2018.

OBJECTIVE:To characterize trends in and risk factors for venous thromboembolism (VTE) during delivery hospitalizations in the United States. METHODS:The 2000-2018 National Inpatient Sample was used for this repeated cross-sectional analysis. Venous thromboembolism (including deep vein thrombosis [DVT] and pulmonary embolism) during delivery hospitalizations for women aged 15 to 54 years was determined by year. Temporal trends in VTE were characterized using joinpoint regression with estimates presented as the average annual percent change. Temporal trends in common VTE risk factors were also analyzed. The proportion of vaginal and cesarean deliveries by year that had VTE risk factors was determined, and average annual percent changes with 95% CIs were calculated. The relationship between risk factors and the likelihood of VTE events was determined with adjusted and unadjusted logistic regression models. RESULTS:Of 73,109,789 delivery hospitalizations, 48,546 VTE events occurred (6.6/10,000 deliveries), including 37,312 DVT diagnoses and 12,487 pulmonary embolism diagnoses. Rates increased significantly for vaginal (average annual percent change 2.5%, 95% CI 1.5-3.5%) but not for cesarean delivery hospitalizations (average annual percent change 0.3%, 95% CI -1.0 to 1.6%) over the study period. Pulmonary embolism increased for both vaginal delivery (average annual percent change 8.7%, 95% CI 6.0-11.5%) and cesarean delivery (average annual percent change 4.9%, 95% CI 3.6-6.2%). The proportion of cesarean deliveries with at least one VTE risk factor increased from 27.2% in 2000 to 43.6% in 2018 (average annual percent change 2.6%, 95% CI 2.2-3.1%) and for vaginal deliveries, from 17.7% to 31.4% (average annual percent change 3.4%, 95% CI 2.3-4.4%). The 5.9% of deliveries with at least two VTE risk factor diagnoses accounted for 25.4% of VTE diagnoses. Factors with the highest VTE risk included transfusion (adjusted odds ratio [aOR] 4.1, 95% CI 3.7-4.5), infection (aOR 5.8, 95% CI 5.3-6.3), history of VTE (aOR 7.2, 95% CI 6.2-8.4), and thrombophilias (aOR 9.6, 95% CI 8.5-11.0). CONCLUSION:Both risk factors for VTE and rate of pulmonary embolism increased over the study period. Deep vein thrombosis increased during vaginal delivery hospitalizations but not during cesarean delivery hospitalizations.