Relative importance of posttraumatic stress disorders and depression in predicting risk of suicide among a cohort of Vietnam veterans

Objective
Research has demonstrated that posttraumatic stress disorder (PTSD) among Vietnam veterans is associated with increased risk of suicide. It is also widely reported that suicide is related to depression. This study examined the effect of PTSD and depression on risk of suicide among a cohort of Vietnam veterans.
Method
All study subjects were selected from the Department of Veterans Affairs Agent Orange Registry. Suicide risk associated with PTSD was first assessed by comparing the number of suicides among a cohort of 2,874 veterans with PTSD to that of 8,537 veterans not diagnosed with PTSD. Risk of suicide was approximated by hazard ratios (HRs), generated by Cox proportional hazard models, including a model that utilized competing risk analyses.
Results
The risk of suicide associated with PTSD and depression when examined separately was similar, HR = 7.1 (95% confidence interval (CI): 4.9, 10.3) and HR = 7.2 (95% CI: 4.8–10.8), respectively. Competing risk analysis indicated that veterans with both PTSD and depression compared to veterans with neither diagnosis had the highest risk of suicide, HR = 15.22.
Conclusions
This study suggests that depression as well as PTSD should be monitored as a way of reducing suicides among Vietnam veterans.