SLE Associated With Hypertensive Disorders in Pregnancy and Cardiovascular Disease Later in Life, Study Finds
Hypertensive disorders of pregnancy (HDP) are more common in pregnant women with systemic lupus erythematosus than those without the chronic autoimmune disease, and pose an increased risk of heart disease and high blood pressure later in life, a large Swedish study shows.
The study, “Maternal hypertensive disorders in SLE pregnancy and future cardiovascular outcomes,” was published in Arthritis Care & Research.
HDPs are conditions involving hypertension (high blood pressure) during pregnancy, such as preeclampsia. Broadly, such conditions are thought to be associated with an increased risk of cardiovascular disease (CVD), such as stroke, later in life.
Systemic lupus erythematosus (SLE) is also associated with an increased risk of CVD, and inflammatory diseases such as SLE are known risk factors for preeclampsia. Despite this, the effect of HDP on cardiovascular complications later in life among people with SLE who become pregnant have not been rigorously studied.
Researchers analyzed data from the Swedish Medical Birth Register, which includes data on nearly every birth in Sweden from July 2008.
The team identified 450 women with SLE who gave birth for the first time, and a corresponding group of 2,890 women without this disease who first gave birth between 1987 and 2012. The two groups had similar age (mean of 30 years at delivery), body mass index, and country of birth. No pregnancies of twins were included in the analysis.
Overall, the incidence rates of CVD were 50 cases per 10,000 person-years among women with SLE, and 7.2 cases per 10,000 person-years among those without the disease. Person-years is a measure that sums actual follow-up duration in each patient and is higher with more years in study.
Also, HDPs were more common among SLE pregnancies than in those without the disease (20% vs. 7%).
Among pregnancies with HDP, the rate of CVD was higher in women with SLE (89 vs. 12 cases per 10,000 person-years). Further statistical analyses suggested a nearly two-fold increased risk of CVD among women with SLE who experienced HDP. In women without SLE, having HDP increased the risk of CVD by about 70%.
In addition, the incidence rate of stroke was 60.6 events per 10,000 person-years in pregnancies with HDP and SLE. In those with HDP but not SLE, no cases of post-pregnancy stroke were reported.
Likewise, hypertension developing after pregnancy was more common among people with HDP and SLE than among those with HDP and no SLE (524 vs. 177 cases per 10,000 person-years). Subsequent analyses suggested an approximately three-fold increased risk of hypertension among people who experienced HDP, both for those with and without SLE.
As SLE itself is associated with an increased risk of CVD, the researchers performed an analysis to assess the extent to which HDP mediates the association between the two disorders. Results showed that HDP explained about 10% of the association between SLE and CVD, and about 20% of the association between SLE and hypertension later in life.
The researchers noted that the rates of CVD in their study are somewhat low, likely owing to the relatively young age of the studied population — average age under 45 years at the end of follow-up, which lasted a median of 10.8 years. Future studies with longer follow-up times will be necessary to validate these results.
“Our data confirm that women who experience a hypertensive disorder in pregnancy are at greater risk of developing hypertension after pregnancy, and that this association is also evident for women with SLE,” the researchers wrote. “Women with SLE and HDP were also at increased risk of CVD, particularly stroke, at young ages and should be monitored closely and consider treatment to attenuate risk.”