Chronic hypertension diagnosed by the American Heart Association and American College of Cardiology criteria is associated with increased risk of developing hypertensive disorders of pregnancy

Abstract

ACOG uses a systolic blood pressure (SBP) ≥140 or diastolic blood pressure (DBP) ≥90 documented at <20 weeks of gestation to define chronic hypertension. In the nonpregnant state, the American Heart Association (AHA) and the American College of Cardiology (ACC) define chronic hypertension using lower diagnostic thresholds of SBP ≥130 or DBP ≥80. It remains unclear whether using more conservative guidelines in pregnancy improves identification of those at risk for gestational hypertension (GHTN) or preeclampsia (PRE). We sought to investigate whether subjects with chronic hypertension (CHTN) based on AHA/ACC criteria had an increased risk for GHTN and PRE compared to those without CHTN. We conducted a retrospective cohort study utilizing a clinical database at a diverse, large urban, safety-net hospital. Subjects ages 18-40 with singleton gestations and 1st trimester prenatal care were included. We defined subjects that met criteria for Stage 1 Chronic Hypertension based on 1st trimester SBP and DBP cutoffs satisfying the AHA/ACC criteria (SBP ≥130 or DBP ≥80). Those who did not meet these criteria had an SBP<130 and a DBP <90. We did not include those with CHTN based on ACOG criteria in this cohort (SBP ≥140 or DBP ≥90 at <20 weeks); as such those who met the AHA/ACC criteria solely consisted of subjects with SBP=130-139 and DBP=80-89. By doing this, we were able to specifically investigate the increased risk for this specific population which remains unclear. Diagnoses of GHTN and PRE were based on established ACOG criteria. PRE included those with and without severe features. Tests for normality were performed. Student t-tests or Rank sum tests were performed as appropriate for continuous variables; Chi-square or Fisher's exact tests were performed for categorical variables. Generalized linear models were performed to calculate risk ratios while controlling for appropriate confounders. Of N=3,354 subjects, 18% (n=629) were diagnosed with Stage 1 CHTN based on AHA/ACC criteria. Those with AHA/ACC Stage 1 CHTN had increased rates of GHTN (35.4% vs 20%, p<0.001) and PRE (22.3% vs 10%, p<0.001) compared to those without Stage 1 CHTN based on these criteria. When controlling for maternal age, race 1st trimester body mass index (BMI), pregestational diabetes and substance use, those with AHA/ACC Stage 1 CHTN had an almost 1.5-fold higher adjusted risk ratio (ARR) of experiencing GHTN (ARR 1.49 ± 0.10, p<0.001) and almost 2-fold increased ARR of experiencing PRE (ARR 1.98 ±0.19, p<0.001). Our data suggest an increased risk for developing GHTN and PRE for subjects satisfying the AHA/ACC cutoff for Stage 1 CHTN. Future studies need to consider whether diagnosis of CHTN in pregnancy should conform with AHA/ACC criteria, and if those with Stage 1 CHTN based on AHA/ACC criteria require the same preventative measures and interventions utilized by those diagnosed by ACOG criteria.