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435: Racial disparity in the treatment of severe hypertension with labetalol

      Objective

      Labetalol has been shown to be less effective in the non-pregnant black population compared to other ethnicities in treating hypertension. The objective of this study was to test if there is a correlation between race/ethnicity and blood pressure response to IV labetalol in the pregnant population.

      Study Design

      This was a retrospective study of patients who received IV labetalol for management of severe hypertension (SHTN) in pregnancy, from 10/2013- 12/2017, in an urban hospital. SHTN was defined as a systolic blood pressure ≥ 160 or a diastolic blood pressure ≥ 110. IV labetalol administration was given based on the ACOG protocol for treatment of SHTN. Patients with multifetal gestation or who were given other anti-hypertensive medications were excluded. The primary outcome was association between race/ethnicity and response to IV labetalol. Chi-square and multivariable logistic regression models were utilized to determine the association between the proportion of responders and ethnic groups, collectively and at each administration of labetalol.

      Results

      367 patients received IV labetalol for SHTN. Ethnicity was self-identified by patients. There were 134 Black, 161 White, 29 Asian, and 43 Hispanic patients. White and Asian patients were significantly older than other racial groups while Hispanic and Black patients had a significantly higher BMI (p<0.001). After adjusting for age and BMI, there was a significant association between ethnicity and response to the first dose of labetalol with Hispanic patients being the most responsive, followed by Asian and White patients, and then Black patients being the least responsive (p=0.03) (Figure 1, Figure 2). After the first dose of medication, there was no significant association between race/ethnicity and overall response to labetalol (Figure 2).

      Conclusion

      Our data suggest a significant association between ethnicity and response to the first dose of labetalol, with Black women being the least responsive. A finding not previously seen in the literature was that Hispanic women were the most responsive to labetalol. In the face of a finding of racial disparity in drug efficacy, further studies of a genetic predisposition are suggested.
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