Abstract 119: Using Blood Pressure Values from Electronic Medical Records to Identify Hypertension During Pregnancy

Objective: Hypertension is a major risk factor for poor pregnancy outcomes. Many observational studies have relied on diagnosis codes, particularly from the delivery hospitalization, to identify hypertension in pregnancy. We augmented diagnosis codes with electronic blood pressure (BP) data to improve the identification of pregnant women with hypertension. Methods: We studied pregnant women aged 15-49 years enrolled in three Kaiser Permanente health plans who delivered during 2005-2014. Using diagnosis codes, BP values, and antihypertensive medication dispensings, we defined hypertension as: (1) ≥ 2 high BPs (≥ 140/90 mmHg) within 30 days of each other (2highBPs); or (2) ≥ 1 antihypertensive medication fill with ≥1 hypertension diagnosis code from 120 days prior to pregnancy through 20 weeks gestation (chronicHTN); or (3) ≥ 1 high BP, a hypertension diagnosis code, and an antihypertensive fill within 7 days (RapidTx). Among women meeting our study definition, we examined receipt of hypertension diagnosis codes and prevalence of severe hypertension (1+ BP ≥160/110 mmHg). Results: Among 553,477 eligible women, 29,933 (5%) met our definition of hypertension, including 26,855 identified via 2highBPs, 5,774 via chronicHTN and 6,198 via RapidTx (not mutually exclusive). Among women meeting our hypertension definition overall, only 64% had 1+ hypertension diagnosis code assigned during pregnancy, and 49% had one at delivery. Among hypertensive women identified via 2highBPs, only 60% (16,057/26,855) had a hypertension diagnosis code in pregnancy and 45% (12,131/ 26,855) at delivery. However, 53% of our hypertensive women (14,972/ 29,933) overall and 56% (14,972/ 26,855) of the 2highBPs women had severe hypertension at some time during pregnancy. Conclusion: Incorporating BP values identifies additional pregnant women with hypertension who would have been missed by approaches using diagnosis codes alone. Women identified by our method frequently had severely elevated BP, showing the importance of including these women in future studies of hypertension during pregnancy.