Pregnancy outcomes in patients with systemic vasculitis in the USA from 2007 to 2022: an administrative claims-based...

Systemic vasculitides are rare, heterogeneous, inflammatory disorders associated with high morbidity and mortality. Recent therapeutic advancements have improved life expectancy and reproductive opportunities for patients with vasculitis, but research on preterm delivery, maternal pregnancy complications, and medication use is limited. We aimed to investigate pregnancy outcomes in patients with systemic vasculitis using administrative claims data.

In this administrative claims-based study, we identified pregnancies in patients aged 15-44 years at the time of delivery with and without (referent population) systemic vasculitis in the Merative MarketScan Commercial Databases from Jan 1, 2007, to Dec 31, 2022. The database includes de-identified inpatient and outpatient health encounters (of mostly privately insured patients) with employment-sponsored health insurance claims in the USA. For patients with vasculitis, at least two outpatient or one inpatient ICD ninth revision clinical modification or ICD tenth revision clinical modification vasculitis-coded visits occurring before or on the last menstrual period of the index pregnancy were required for inclusion in the study. Systemic vasculitis was categorised by vessel size; large, medium, small, and variable. We established the rate of adverse pregnancy outcomes, including hypertensive disorders of pregnancy, placental disorders, and preterm delivery phenotypes in both groups. We also described pregnancy characteristics, medication use, and complications in patients with systemic vasculitis stratified by parity. Outcomes were compared using minimally adjusted and propensity score-adjusted regression models. People with lived experience of vasculitis were not included in this study.

We included 729 pregnancies in 568 patients with vasculitis. 61 (8·4%) were in pregnancies of patients with large vessel vasculitis, 171 (23·5%) with medium vessel vasculitis, 247 (33·9%) with small vessel vasculitis, and 274 (37·6%) with variable vessel vasculitis. 8243 pregnancies in 5680 obstetric patients without vasculitis were included in the referent population. The median age at delivery was higher in the patients with vasculitis than in those in the referent population (33 years [IQR 29-36] vs 31 years [28-35]). Glucocorticoids were the most common treatment during pregnancy in patients with systemic vasculitis, with 159 (21·8%) receiving other immunosuppressive medications. Preterm delivery (before 37 weeks completed gestation) risk was higher in patients with vasculitis than in the referent population, with increased risk in both the minimally adjusted model (adjusted risk ratio [RR] 1·76 [95% CI 1·33-2·33]) and propensity score-adjusted model (propensity score-adjusted RR 1·52 [1·13-2·03]). Pre-eclampsia or eclampsia also occurred at a higher frequency in the population with systemic vasculitis than in the referent population in both models (minimally adjusted RR 1·91 [1·45-2·52] and propensity score-adjusted RR 1·51 [1·11-2·07]). For both preterm delivery and pre-eclampsia or eclampsia, the risk varied by parity and vessel size.

Pregnancies in patients with vasculitis had higher risks of preterm delivery and pre-eclampsia or eclampsia than pregnancies in the referent obstetric population. Although the contribution of disease-specific factors and comorbidities on these outcomes requires further investigation, these findings affirm the importance of pre-conception counselling and regular monitoring during pregnancy.

Stanford Maternal Child Health Research Institute; Stanford Institute for Immunity, Transplantation, and Infection; and Stanford Autoimmune and Allergy Supergroup.