The incidence and prevalence of anxiety disorder, depression, and bipolar disorder are higher among patients with rheumatoid arthritis than individuals from the general population, according to findings from a Canadian retrospective matched cohort study.

In the study of 10,206 rheumatoid arthritis (RA) patients and 50,960 individuals matched from the general population of Manitoba between 1989 and 2012, depression incidence was higher in the RA group, compared with the matched group, when adjusted for factors including age, sex, year, region of residence, and socioeconomic status (incidence rate ratio = 1.46; 95% confidence interval, 1.35-1.58). Incidence of anxiety disorder (IRR = 1.24; 95% CI, 1.15-1.34) and bipolar disorder (IRR = 1.21; 95% CI, 1.00-1.47) were also higher in the RA group. The incidence of schizophrenia did not differ between groups (IRR = 0.96; 95% CI, 0.61-1.50), Ruth Ann Marrie, MD, PhD, of the University of Manitoba, Winnipeg, and her coauthors reported in Arthritis Care & Research .

The investigators obtained the data from the Population Registry, Discharge Abstract Database, Medical Services, and Drug Program Information Network (DPIN) databases from the Manitoba Population Research Data Repository, which covers about 98% of the population. All databases included data from April 1, 1985, through March 31, 2012, except for the DPIN, which became available in 1995.

To estimate psychiatric disorder incidence after RA diagnosis (or the index date in the matched population), the first claim had to occur after the index date, and had to be preceded by a 5-year period with no claims for that psychiatric disorder. To estimate lifetime prevalence, once a patient met the case definition for a disorder, he or she was considered affected in all subsequent years if alive and a Manitoba resident. To account for varying periods of remission, however, annual period prevalence was defined as a patient having one or more hospital claims or two or more physician claims for the disorder in that year, Dr. Marrie and her colleagues wrote.

The adjusted lifetime prevalence was also higher in the RA group for both depression (PR = 1.35; 95% CI, 1.26-1.45) and anxiety disorder (PR = 1.20; 95% CI, 1.13-1.27), as was the annual period prevalence of depression (PR = 1.36; 95% CI, 1.26-1.47) and anxiety disorder (PR = 1.30; 95% CI, 1.19-1.41). Neither lifetime prevalence of bipolar disorder (PR = 1.13; 95% CI, 0.95-1.36) and schizophrenia (PR = 1.02; 95% CI, 0.72-1.43) nor annual period prevalence of bipolar disorder (PR = 1.06; 95% CI, 0.86-1.31) and schizophrenia (PR = 0.68; 95% CI, 0.40-1.15) differed between the RA and matched cohorts, the authors reported.

Female sex was associated with risk of psychiatric disease, as was lower socioeconomic status and living in an urban area, the authors reported.

Although the study had strengths including a large study population and use of population-based data, it did not evaluate psychiatric multimorbidity, a “common and clinically relevant issue which may affect outcomes,” Dr. Marrie and her coauthors said in the report. Additionally, the use of administrative data makes it difficult to account for care provided by nonphysician providers, such as psychologists, and for conditions that cause symptoms but do not meet diagnostic criteria, the authors noted.

“Future studies should explore these issues in population-based clinical cohorts which comprehensively evaluate multiple psychiatric disorders,” they concluded.

The study was funded by the Canadian Institutes of Health Research and the Waugh Family Chair in Multiple Sclerosis. Dr. Marrie has conducted clinical trials for Sanofi Aventis. Two other authors disclosed financial ties to pharmaceutical companies.

SOURCE: Marrie R et al. Arthritis Care Res. 2018 Feb 13. doi: 10.1002/acr.23539.