Contribution To Literature:
The CHAP trial showed that antihypertensive therapy improves pregnancy outcomes among pregnant women with mild chronic hypertension.
Description:
The goal of the trial was to evaluate antihypertensive therapy compared with control among pregnant women with mild chronic hypertension.
Study Design
- Randomized
- Parallel
- Open-label
Pregnant individuals with mild chronic hypertension were randomized to a blood pressure goal <140/90 mm Hg (active treatment) (n = 1,208) versus control (n = 1,200). In the control group, antihypertensive therapy was withheld unless the blood pressure was ≥160/105 mm Hg.
In the active treatment group, patients received standard first-line antihypertensive agents in pregnancy (labetalol or extended-release nifedipine); however, amlodipine or methyldopa could also be used, if needed. The medication was titrated to the maximum dose, as necessary, before starting a second agent.
- Total number of enrollees: 2,408
- Duration of follow-up: 34 weeks
- Mean patient age: 32 years
- Percentage with diabetes: 15.8%
Inclusion criteria:
- Pregnant women with mild chronic hypertension
- Known chronic hypertension was confirmed by elevated blood pressure and previous/current antihypertensive therapy, while new chronic hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 on ≥2 occasions ≥4 hours apart
- Gestational age <23 weeks
Exclusion criteria:
- Need for >1 antihypertensive medication, secondary hypertension, multiple fetuses, high-risk illnesses, or complications that could warrant treatment at a lower blood pressure level
- Obstetric conditions that increase fetal risk
- Contraindications to first-line antihypertensive drugs in pregnancy
Other salient features/characteristics:
- Non-Hispanic black women: 48%
- Mean body mass index: 37.5 kg/m2
- Mean systolic blood pressure between randomization and delivery: 129.5 mm Hg in the active treatment group vs. 132.6 mm Hg in the control group
Principal Findings:
The primary outcome, composite of pre-eclampsia with severe features, medically indicated preterm birth at <35 weeks’ gestation, placental abruption, or fetal/neonatal death, occurred in 30.2% of the active treatment group vs. 37.0% of the control group (p < 0.001).
Secondary outcomes:
- The safety outcome, small-for-gestational-age birth weight below the 10th percentile for gestational age: 11.2% in the active treatment group vs. 10.4% in the control group (p = 0.56)
- Pre-eclampsia with severe features: 23.3% in the active treatment group vs. 29.1% in the control group
- Fatal/neonatal death: 3.5% in the active treatment group vs. 4.3% in the control group
Interpretation:
Among pregnant women with mild chronic hypertension, antihypertensive therapy targeted to a blood pressure <140/90 mm Hg reduced the incidence of adverse pregnancy outcomes compared with usual care. Active treatment improved outcomes without increasing the risk for low birth weight. A large proportion of non-Hispanic blacks were enrolled in this trial.
References:
Tita AT, Szychowski JM, Boggess K, et al., on behalf of the Chronic Hypertension and Pregnancy (CHAP) Trial Consortium. Treatment for Mild Chronic Hypertension During Pregnancy. N Engl J Med 2022;Apr 2:[Epub ahead of print].
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