Hydroxychloroquine and Pre-eclampsia in a Diverse Cohort of Women with Systemic Lupus Erythematosus

ObjectivePatients with systemic lupus erythematosus (SLE) are at risk for pregnancy complications such as pre-eclampsia and eclampsia. These clinically important complications are associated with maternal morbidity, mortality, and postpartum cardiovascular disease. Some studies suggest that hydroxychloroquine (HCQ) may reduce pre-eclampsia risk in lupus pregnancy. Using a cohort of pregnant patients with prevalent SLE at Kaiser Permanente Northern California (KPNC), we investigated whether HCQ treatment in early pregnancy reduced the risk of pre-eclampsia or eclampsia.MethodsAmong pregnant patients with SLE from 2011 to 2020, we assessed HCQ treatment from three months before pregnancy through the first trimester. HCQ exposure was defined multiple ways to account for adherence and duration of treatment. Propensity scores accounted for multiple confounders and modified Poisson models estimated risk ratios (RRs) and 95% confidence intervals of the association between HCQ treatment and pre-eclampsia or eclampsia. Effect modification by pregestational hypertension, history of nephritis, and antiphospholipid antibody (aPL) status was investigated through stratified analysis.ResultsThere were 399 pregnancies among 324 patients with SLE at KPNC between 2011 and 2020. Considering multiple exposure definitions, we consistently found a null association between HCQ and pre-eclampsia or eclampsia. The RRs were consistently lower among nullipara patients, and RRs were consistently protective but not statistically significant among the high-risk subgroup of patients with a history of nephritis, aPL positivity, or pregestational hypertension (for both nullipara and multipara patients).ConclusionAlthough this study found no reduced risk of HCQ on pre-eclampsia or eclampsia, residual confounding may be attenuating the effect despite an integrated health care delivery system setting with detailed clinical data.