Risk of rhabdomyolysis in patients with mental disorders.

Objectives: Rhabdomyolysis is caused by rapid muscle breakdown. Although patients with mental disorders are more susceptible to rhabdomyolysis, its incidence in this group is poorly established. Therefore, we conducted a population-based cohort study to investigate its incidence and risk in this group.

Methods: We conducted a retrospective cohort study of 120,094 patients with mental disorders and 120,094 control patients from the Taiwan National Health Insurance Research Database. We excluded patients with rhabdomyolysis diagnosed before the index date, which was defined as the date of the first diagnosis of the mental disorder and beginning of antipsychotic medication. We matched the case cohort 1:1 with a control cohort by a propensity score method.

Results: The overall incidence of rhabdomyolysis were 3.21 per 1000 person-years in the patients with mental disorders and 1.16 per 1000 person-years in the patients without mental disorders. After controlling for potential covariates, the patients with mental disorders showed an adjusted hazard ratio (aHR) of 2.77 (95% Cl: 2.62-2.92) compared with the controls. Men exhibited a risk of rhabdomyolysis 1.29-fold that exhibited by women (95% CI: 1.22-1.35). Alcoholic liver disease (aHR, 2.35) and generalized convulsive epilepsy (aHR, 2.06) were independent risk factors for rhabdomyolysis. Phenothiazines with aliphatic side-chains (aHR, 1.43), or piperidine structures (aHR, 1.54); butyrophenone derivatives (aHR, 1.24); lithium (aHR, 1.18) were independent risk factors for rhabdomyolysis after adjustment for covariates.

Conclusions: The risk of rhabdomyolysis is significantly higher for patients with mental disorders than that for patients without mental disorders.