and death rates due to suicide and accidental death before 1999 may not be readily comparable with data from 1999 on (Anderson et al. 2001; Hoyert et al. 2001). In 2003, the National Center for Health Statistics (NCHS) revised the ICD-10 Injury Mortality Matrix to finalize groupings of external cause-of-injury classifications; this affected groupings related to both suicide and motor-vehicle accidental deaths. The best way to address discrepancies in how clinicians and researchers define suicidal behaviors is still being debated. Thus, underlying all the studies considered in this section is an inevitable limitation related to a potential for bias due to the inconsistency of case definition of suicide and accidental death among studies of veterans that were conducted over decades. Further limitations may be related to the presence of unknown bias due to misclassification of accidental deaths, some of which may be suicides, and to potential underreporting. However, those potential sources of bias are likely to occur equally among veterans and nonveterans, so it was critical to assess the inclusion of an appropriate control or reference group in the studies evaluated here.
The committee concludes that there is sufficient evidence of an association between deployment to a war zone and suicide in the early years after deployment. The committee also concludes that there is sufficient evidence of an association between deployment to a war zone and accidental death in the early years after deployment.