Post doctoral fellow University of Montreal, Canada
Background: Autoimmune diseases (AD) affect 5-8% of the population with a higher prevalence in women, often occur in childbearing age, including pregnancy. The prevalence of AD is increasing, and associated with more co-morbidities and high drug burden compared to the general population.
Objectives: To determine the prevalence of AD in Quebec, to compare the characteristics of these women in general and by AD types to those of the general population, and to describe drug use.
Methods: All pregnancies from the population-based Quebec Pregnancy Cohort (QPC), covered by the public drug plan (1998-2015) were included. Pregnant women with at least 1 diagnosis of AD (inflammatory bowel diseases (IBD), rheumatoid arthritis (RA), spondyloarthritis (SpA), connective tissue disease or systemic lupus erythematosus (CTD/SLE), vasculitis) in the year before pregnancy were compared to those without AD. Socio-demographic characteristics, co-morbidities, prevalence of drug use before and during pregnancy were compared with logistic regression (any AD to those without AD, and specific AD to those without AD).
Results: Of the 441,570 pregnancies included in the cohort, 3,671 (0.8%) had at least one AD: IBD (57.3%), RA (17.0%), SpA (11.1%), CTD/SLE (10.4%), and vasculitis (1.8%). The prevalence of AD did not change statistically over time (p for trend=0.62). Chronic hypertension, diabetes mellitus, asthma, depression/anxiety were more prevalent in pregnancies with AD diagnosis (p < 0.001). Compared to pregnant women without AD, the most prevalent co-morbidities were chronic hypertension in the CTD/SLE cohort (19% vs 3.9%, p< 0.001); diabetes mellitus and asthma in the vasculitis cohort (12% and 31% vs 3.3% and 15%, p< 0.001); and depression and anxiety in pregnancies with more than one diagnosis (40% vs 27%, p< 0.001). Pregnancies with AD diagnosis took more different drugs than those without: 5.4 (4.9) vs 2.6 (3.0) in the year before pregnancy (p < 0.001) and 3.2 (3.6) vs 1.7 (2.2) during pregnancy (p < 0.001). During pregnancy, women with more than one diagnosis had the highest level of corticosteroids (23% vs 1.2%, p< 0.001), antibiotics (38% vs 27%, p=0.04), opioids (21% vs 5.2%, p< 0.001) and antidepressant/anxiolytic use (16% vs 7.4%, p< 0.001) use. There was no statistical difference for rate of delivery, abortion or spontaneous abortion according to AD subtypes.
Conclusions: Prevalence of AD in the QPC is 0.9%, lower than in general population considering the selection of some AD and childbearing women. Our study shows higher rates of co-morbidities and medication use in pregnant women with AD compared to those without AD and illustrates the complexity of studying pregnancy outcomes in these women, due to potential confounding by these co-morbidities and drugs.
