Background Inflammatory arthritis is associated with the development of mental health disorders. However, there is limited data on the risk of serious mental health outcomes following a rheumatoid arthritis (RA) or ankylosing spondylitis (AS) diagnosis.

Objectives To estimate the risk of deliberate self-harm in patients with ankylosing spondylitis or rheumatoid arthritis compared with the general population.

Methods We evaluated population-based cohorts of RA (n=53,240) and AS (n=13,964), each matched 1:4 by age, sex, and calendar year (at diagnosis) with non-IA comparator cohorts in Ontario, Canada. Individuals with a history of mental illness or prior episode of deliberate self-harm were excluded. The outcome was a first emergency room presentation for deliberate self-harm, subsequent to RA or AS diagnosis, between April 1, 2002 and March 31, 2016. We estimated hazard ratios (HR) and 95% confidence intervals (95% CI) for RA and AS, separately, versus the comparator groups, adjusting for demographic, clinical and health service utilisation variables.

Results Individuals with AS were more likely to deliberately self-harm (incidence rate [IR] of 6.79/10,000 person years [PY] compared to 3.19/10,000 PY in comparators, with an adjusted HR 1.82 (95% CI: 1.26 to 2.62). Deliberate self-harm was also increased for individuals with RA (IR 3.51/10,000 PY) compared to comparators (IR 2.45/10,000 PY) only before (HR 1.43, 95% CI: 1.16 to 1.75), but not after covariate adjustment (HR 1.09, 95% CI: 0.88 to 1.36). The most frequent method of self-harm was poisoning (64% of attempts in AS, 81% in RA) or self-mutilation (36% in AS, 18% in RA).

Conclusions There is a significantly increased rate of self-harm attempt in inflammatory arthritis and the risk is particularly elevated following a diagnosis of AS. These findings highlight the need for routine evaluation of self-harm behaviour as part of the management of chronic inflammatory arthritis. Understanding the mechanisms contributing to deliberate self-harm attempts will help tailor preventive strategies to reduce morbidity associated with this serious mental health outcome.

Acknowledgements This work was funded by the Division of Rheumatology Pfizer Research Chair, University of Toronto

Disclosure of Interest None declared