Hypertensive disorders of pregnancy (HDPs) increase cardiovascular disease (CVD) risk. Pregnancy morbidities, including preeclampsia and CVD, are common in systemic lupus erythematosus (SLE). Possible connections are important to explore. In a population-based cohort, we investigated whether HDPs are associated with a higher risk of cardiovascular outcomes separately in women with SLE and those without SLE to examine the role of SLE.
We identified first singleton births in the Medical Birth Register (1987-2012) among mothers with SLE and a large general population comparison group. Discharge diagnoses for HDPs, cardiovascular outcomes, and hypertension in the National Patient Register were identified using International Classification of Diseases codes. We estimated adjusted hazard ratios and 95% confidence intervals of the association between HDPs and outcomes in separate models in women with and without SLE. We then evaluated additive and multiplicative effect modification using relative excess risk due to interaction and Cox models jointly accounting for SLE and HDPs, respectively. Mediation analysis estimated the proportion of the association between SLE and outcome explained by HDPs.
HDPs were more common in pregnant women with SLE (20% versus 7%). In SLE, HDPs were associated with a 2-fold higher rate of cardiovascular outcomes and a 3-fold higher rate of incident hypertension. HDPs mediated 20% of the latter association. In women without SLE, HDPs were associated with higher incidence of hypertension later in life.
In women with SLE and those without SLE, HDPs were associated with a 3-fold higher rate of hypertension. In SLE, women with HDPs developed cardiovascular outcomes twice as often as women without HDPs.