Psychiatric comorbidity increases mortality in immune-mediated inflammatory diseases

Abstract

Objective: We determined the association between any common mental disorder (CMD: depression, anxiety disorder, bipolar disorder) and mortality and suicide in three immune-mediated inflammatory diseases (IMID), inflammatory bowel disease (IBD), multiple sclerosis (MS) and rheumatoid arthritis (RA), versus age-, sex- and geographically-matched controls.

Methods: Using administrative data, we identified 28,384 IMID cases (IBD: 8695; MS: 5496; RA: 14,503) and 141,672 matched controls. We determined annual rates of mortality, suicide and suicide attempts. We evaluated the association of any CMD with all-cause mortality and suicide using multivariable Cox regression models.

Results: In the IMID cohort, any CMD was associated with increased mortality. We observed a greater than additive interaction between depression and IMID status (attributable proportion 5.2%), but a less than additive interaction with anxiety (attributable proportion -13%). Findings were similar for MS and RA. In IBD, a less than additive interaction existed with depression and anxiety on mortality risk. The IMID cohort with any CMD had an increased suicide risk versus the matched cohort without CMD.

Conclusion: CMD are associated with increased mortality and suicide risk in IMID. In MS and RA, the effects of depression on mortality risk are greater than associations of these IMID and depression alone.

Keywords: Anxiety disorder; Bipolar disorder; Depression; Immune-mediated inflammatory disease; Mortality.