The Cumulative Burden of Mental, Substance Use, and General Medical Disorders and Rehospitalization and Mortality After an Injury.

Objective: Each year in the United States, 1.5-2.5 million individuals require hospitalization for an injury. Multiple mental, substance use, and chronic general medical disorders are endemic among injury survivors with and without traumatic brain injury (TBI), yet few studies have assessed the association between the cumulative burden of these conditions and health care outcomes. This study of patients hospitalized for an injury assessed associations between comorbid mental, substance use, and general medical disorders, TBI, and violent events or suicide attempts and the postinjury outcomes of recurrent hospitalization and death.

Methods: Recurrent hospitalization and all-cause mortality were examined in this population-based retrospective cohort study. A total of 76,942 patients hospitalized for an injury in Washington State during 2006-2007 were followed for five years. ICD-9-CM codes identified conditions prior to or at the index injury admission. Index admissions related to injuries from firearms, assaultive violence, suicide attempts, and overdoses were identified through E-codes.

Results: Adjusted regression analyses demonstrated a significant, dose-response relationship between an increasing cumulative burden of disorders and an increasing risk of recurrent hospitalization (four or more conditions, relative risk=3.89, 95% confidence interval [CI]=3.66-4.14). Adjusted Cox proportional hazard regression demonstrated a similar relationship between increasing cumulative burden of disorders and all-cause mortality (four or more conditions, hazard ratio=5.33, CI=4.71-6.04).

Conclusions: Increasing cumulative burden of disorders was associated with greater postinjury risk of recurrent hospitalization and death. Orchestrated investigative and policy efforts could introduce screening and intervention procedures that target this spectrum of comorbidity.