Study Suggests Substance Use Disorders Significantly Increase the Risk of All-Cause Mortality among Veterans with PTSD
BACKGROUND:
The association between substance use disorders (SUDs) and PTSD has been well documented in previous studies. Further, there is evidence that among individuals with psychiatric disorders, SUDs may contribute to excess mortality. Nonetheless, little is known about the potential influence of co-occurring SUDs on the risk of mortality among individuals with PTSD. This study sought to estimate the predictive association between SUDs and the risk of mortality among a cohort of Veterans with PTSD. Investigators also examined whether this association was greater for injury-related as opposed to non-injury-related mortality, and whether age influences this association. Using VA data, investigators identified 272,509 Veterans who used VA healthcare services in FY2004 and were diagnosed with PTSD. This cohort was followed from FY05 through FY07. Veterans were stratified into three age groups: < 45 years old, 45-64 years old, and > 65 years old. The main outcome measures were mortality and cause of death. Results were adjusted for demographics, service connection, tobacco use disorder, major depression, bipolar disorder, other anxiety disorders, personality disorders, schizophrenia, and medical comorbidity.
FINDINGS:
- Having a substance use disorder significantly increased the risk of all-cause mortality among Veterans with PTSD.
- The association between SUDs and non-injury-related mortality was most pronounced in the youngest age group (< 45 years), which included OEF/OIF Veterans, compared with the 45-64 or > 65 group.
- Regardless of age group, SUD was a strong predictor of injury-related mortality. It was a significantly stronger predictor of injury-related vs. non-injury related death among Veterans in the 45-64 years and >65 years age groups. However, it is important to note that injury-related mortality accounted for a relatively small proportion of all deaths (~10%) among Veterans with PTSD.
LIMITATIONS:
- Causal interpretations cannot be made due to the observational nature of the study design; it is unknown whether having an SUD causes death among individuals with PTSD.
- Although investigators adjusted for several confounding variables, residual confounding may remain.
- Vital status and cause of death data were obtained from CDC National Death Index records, which are limited by incomplete and potentially inaccurate data, i.e., misclassification of cause of death.
AUTHOR/FUNDING INFORMATION:
This study was funded by HSR&D. Drs. Bohnert, Ilgen, and Blow and Ms. Austin are part of the Serious Mental Illness Treatment Resources and Evaluation Center (SMITREC), VA Ann Arbor Healthcare System, and are part of HSR&D Center for Clinical Management Research, Ann Arbor.
Bohnert K, Ilgen M, Rosen C, Desai R, Austin K, and Blow F. The Association between Substance Use Disorders and Mortality among a Cohort of Veterans with Post-Traumatic Stress Disorder: Variation by Age Cohort and Mortality Type. Drug and Alcohol Dependence September 10, 2012;e-pub ahead of print.
