Objective: To examine whether there are racial disparities in severe maternal morbidity in patients with hypertensive disorder of pregnancy (HDP). Study Design: Secondary analysis of an observational study of 115,502 patients who had a live birth at ≥ 20 weeks in 25 hospitals in the US from 2008 to 2011. Only patients with HDP were included in this analysis. Race and ethnicity were categorized as non-Hispanic White, non-Hispanic Black and Hispanic and were abstracted from the medical charts. Patients of other races and ethnicities were excluded. Associations were estimated between race and ethnicity and the primary outcome of severe maternal morbidity, defined as any of the following: blood transfusion ≥4 units, unexpected surgical procedure, need for a ventilator ≥ 12 hours, intensive care unit (ICU) admission, or failure of ≥ 1 organ system, were estimated by unadjusted logistic and multivariable backward logistic regressions. Multivariable models were run classifying HDP into 3 levels: 1) gestational hypertension; 2) preeclampsia (mild, severe or superimposed); and 3) eclampsia or HELLP. Results: A total of 9,612 individuals with HDP met inclusion criteria. No maternal deaths occurred in this cohort. In univariable analysis, non-Hispanic White patients were more likely to present with gestational hypertension whereas non-Hispanic Black and Hispanic patients were more likely to present with preeclampsia. The frequency of the primary outcome, composite severe maternal morbidity, was higher in NHB patients compared with that in non-Hispanic White or Hispanic patients (11.8% vs. 4.5% in non-Hispanic White and 4.8% in Hispanic, p\u3c0.001). This difference was driven by a higher frequency of blood transfusions and ICU admissions among non-Hispanic Black individuals. Prior to adjusting the analysis for confounding factors, the odds ratio (OR) of primary composite outcomes in non-Hispanic black individuals was 2.85 (95% CI 2.38, 3.42) compared to non-Hispanic white. After adjusting for sociodemographic and clinical factors, hospital site, and the severity of HDP, the odds ratios of composite severe maternal morbidity did not differ between the groups (adjusted OR 1.26, 95% CI 0.95, 1.67 for non-Hispanic Black and adjusted OR 1.29, 95% CI 0.94, 1.77 for Hispanic, compared to non-Hispanic White patients). Sensitivity analysis was done to exclude one single site that was an outliner with the highest ICU admissions and demonstrated no difference in ICU admission by maternal race and ethnicity. Conclusions: Non-Hispanic Black patients with HDP had higher rates of the composite severe maternal morbidity compared with non-Hispanic White patients, driven mainly by a higher frequency of blood transfusions and ICU admissions. However, once severity and other confounding factors were taken into account, the differences did not persist
