“What Came First?” Population‐BasedEvaluation of Health Care Encounters for Depression and Anxiety Before and After Inflammatory Arthritis Diagnosis: Disentangling the Relationship Between Mental Health and Arthritis

The study objective was to describe patterns of depression and anxiety health care use before and after diagnosis among patients with inflammatory arthritis (IA), namely, ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis. We used population‐based linked administrative health data from British Columbia, Canada, to build a cohort of individuals (≥18 years) with incident IA and individuals without IA (“IA‐free controls”) matched on age and sex. We computed the proportion of individuals with IA and controls who had one or more depression or one or more anxiety health care encounters and the use of one or more antidepressants or one or more anxiolytics in each yearly interval five years before and after IA diagnosis. We used multivariable logistic regression models to evaluate the association between IA status and aforementioned depression and anxiety health care use outcomes in each yearly interval. A total of 80,238 individuals with IA (62.9% female; mean ± SD age 56.2 ± 16.7 years) and 80,238 IA‐free controls (62.9% female; mean ± SD age 56.2 ± 16.6 years) were identified between January 1, 2001, and March 31, 2018. Individuals with IA had significantly increased odds of depression and anxiety health care encounters and dispensation of antidepressants and anxiolytics for each yearly interval before and after diagnosis. Adjusted odds ratios (ORs) were highest in the year immediately before (one or more depression visits: adjusted OR 1.61, 95% confidence interval [CI] 1.55–1.66; one or more anxiolytics: adjusted OR 1.71, 95% CI 1.66–1.77) or after (one or more antidepressants: adjusted OR 1.95, 95% CI 1.89–2.00) IA diagnosis. Findings suggest a role for depression and anxiety in characterizing the IA prodrome period and generate hypotheses regarding overlapping biopsychosocial processes that link IA and mental health comorbidities.