RISK-FACTORS FOR POSTTRAUMATIC-STRESS-DISORDER IN AUSTRALIAN VIETNAM VETERANS

Objective: The aims of this paper are to determine the risk factors fo r combat-related posttraumatic stress disorder (PTSD) and to examine t he relative contribution of pre-military factors, pre-trauma psychiatr ic diagnoses, military factors such as combat posting, and combat and casualty stress exposure. Method: An epidemiological cohort study usin g standardised psychiatric, social and health interviews was undertake n with a national random sample of male Australian Army Vietnam vetera ns. Multivariate logistic regression was used to examine the relative contribution of factors derived from interview and from military recor ds in four categories: pre-enlistment circumstances including home lif e, education, major life stress; pre-Vietnam psychiatric diagnoses; mi litary experiences before and during Vietnam; and combat and stress ex periences. Results: Of the 128 data items examined, significant associ ations were found for 39, in addition to combat stress. Pre-enlistment items accounted for about 3% of the deviance towards PTSD diagnosis, pre-enlistment psychiatric diagnosis about 13%, military variables abo ut 7% and combat stress about 18%; all factors together accounted for 42%. Conclusions: The results confirm that pre-military and military v ariables make only a small but significant contribution to PTSD either alone or after controlling for combat stress; that psychiatric diagno ses of depression, dysthymia and agoraphobia make strong contributions to PTSD; but that combat stress makes the largest contribution even a fter controlling for the effects of other variables. Psychiatric diagn oses and combat stress appear to be independent in their effects on PT SD.