As with so much else, the vast majority of the research into the epidemiology of post-traumatic illness has looked at post-traumatic stress disorder specifically. However, whereas the combat studies tend to concentrate solely on this, there are a number of civilian trauma-related and disaster-related studies which have looked at the incidence and prevalence of other conditions following trauma exposure.

There are generally three types of epidemiological study which have been carried out in post-traumatic research:

• those looking at patients presenting for treatment

• those looking at identified high-risk groups or at those otherwise selected

• genuine community studies of prevalence.

The last of these seems to be the most important and is the least common. It is unsurprising that community studies of a ‘new’ condition would be preceded by studies of complainants and of high-risk groups. However, there can be no doubt that the only way to estimate the real relevance and importance of the condition is to measure its prevalence in the general population. Such studies do now exist.

Kulka (Kulka et al., 1991) has commented upon the rapid expansion of epidemiological research from relatively small studies in clinical settings, via the congressionally mandated post-Vietnam studies, into population-based or ‘community’ studies. He points out that studies outwith treatment settings present both opportunities and potential hazards. He focuses upon the importance of the diagnostic methods and treatment design used.