Risk of death from accidental overdose associated with psychiatric and substance use disorders.

OBJECTIVE: Despite dramatic increases in the rate of fatal accidental overdose in recent years, risk factors for this outcome remain poorly understood, particularly in clinical populations. The authors examined the association of psychiatric and substance use diagnoses with death from accidental overdose.
METHOD: The study followed a cohort of patients from 2000 to 2006. The cohort included all patients treated in Veterans Health Administration facilities during fiscal year 1999 who were alive at the start of fiscal year 2000 (N=3,291,891). Death by accidental overdose was determined using National Death Index records and defined as a death with underlying cause of death coded to ICD-10 codes X40-X45 (N=4,485). Diagnoses were determined by patient medical records.
RESULTS: Adjusting for demographic and clinical characteristics, hazard ratios of death by accidental overdose associated with prior psychiatric and substance use disorder diagnoses ranged from 1.8 to 8.8. Significant associations of non-substance-related psychiatric disorders with risk of death by accidental overdose persisted after additional adjustment for substance use disorders (hazard ratios from 1.2 to 1.8). Depressive disorders and anxiety disorders other than posttraumatic stress disorder had stronger associations with risk of medication-related overdose death (hazard ratios, 3.02 and 3.07, respectively) than with risk of overdose death related to alcohol or illegal drugs (hazard ratios, 1.89 and 1.23, respectively).
CONCLUSIONS: Among patients receiving care from the Veterans Health Administration, death from accidental overdose was found to be associated with psychiatric and substance use disorders. The study findings suggest the importance of risk assessment and overdose prevention for vulnerable clinical subpopulations.