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Background: This cross-sectional study examined nationwide real-world associations between anti-inflammatory agent fills and suicide-related death rates in 20–24-year-olds across the 21 Swedish regions during 2006–2021.

Methods: Nationwide Swedish registers were used to compare regional year-wise suicide-related mortality (SRM) and dispensations for anti-inflammatory agents (ATC-code: M01) in 20–24-year-olds. Dispensations for paracetamol (ATC-code: N02BE01) was applied as a control variable. Associations between regional year-wise SRM and dispensation rates were analyzed by sex-stratified zero-inflated generalized linear mixed effect models (GLMM). Dispensation rates of paracetamol and inflammatory agents were designated as independent fixed effects variables, and year and region constituted random-intercept effects.

Results: Acetic acid derivatives and related substances (M01AB) and propionic acid derivates (M01A3) accounted for ∼71% of measured dispensation fills for anti-inflammatory agents. Diclofenac fills constituted ∼98% of the former category, whereas dispensations for Ibuprofen (∼21%), Naproxen (∼62%) and Ketoprofen (∼13%) constituted the most prescribed agents in the latter category. Regional yearly dispensation rates of anti-inflammatory agents in 20–24-year-old females were inversely associated with female SRM (β = −0.095, p = 0.0393, 95% CI -0.186, −0.005) – independent of paracetamol rates, which were unassociated to SRM (p = 0.2094). Results were confirmed in validation analyses for anti-inflammatory agents (OR = 0.7232, p = 0.0354, 95% CI [OR] 0.5347, 0.9781). No association was demonstrated in males (p = 0.833).

Conclusion: Anti-inflammatory agent dispensation rates were independently associated to lower suicide-related death rates in female 20-24-year-olds. This adds to growing evidence implicating inflammatory processes in mental disorders, warranting trials focusing on the suicide preventative potential of anti-inflammatories in young adults.