Antiphospholipid antibodies in chronic hypertension: the value of screening during pregnancy

To determine if screening for antiphospholipid antibodies in gravid chronic hypertension patients is warranted, we performed a retrospective cohort study to test the association between antiphospholipid antibodies and perinatal outcome in this group of women. The primary outcome we compared was adverse perinatal outcome, defined as delivery <37 weeks' gestation secondary to maternal or fetal indications, intrauterine or neonatal death, birth weight <10th percentile for gestational age, early-onset severe preeclampsia, or placental abruption. Our sample size allowed for the detection of a 60% reduction in the relative risk of adverse perinatal outcome in patients who were antiphospholipid antibody screen negative (80% power, P = 0.05). No increased risk of adverse perinatal outcome was demonstrated among patients with positive serum antiphospholipid antibodies (33.3%, 5/15) versus patients with negative screening (40.0%, 22/55) in our cohort (RR 0.88, 95% Cl 0.38-1.83). Furthermore, antiphospholipid antibody status was not associated with adverse perinatal outcome after controlling for classic indications for antibody screening (RRMH 0.63, 95% Cl 0.30-1.33). In conclusion, chronic hypertension patients with positive antiphospholipid antibody screening are not at increased risk for adverse perinatal outcome compared to those with negative screening. Therefore, screening for antiphospholipid antibodies in chronic hypertension patients without classic indications for screening is not warranted.