Refugees settled in western countries could be about ten times more likely to have posttraumatic stress disorder than general populations in those countries, suggests a study published in this week’s issue of The Lancet.

Post-traumatic stress disorder is a potentially disabling condition characterised by traumatic flash-backs, hypervigilence, and emotional numbing that might be a risk factor for substance abuse and suicide. About 13 million people are classified as refugees worldwide. Refugees could be at excess risk of psychiatric morbidity because of forced migration, traumatic events, and resettlement in unfamiliar environments. However, the prevalence of mental disorder in these individuals has been unclear.

Mina Fazel (University of Oxford, UK) and colleagues reviewed psychiatric surveys based on interviews with refugee populations in economically developed western countries published between January 1966 and December 2002. They found 20 eligible surveys that included data from 6743 adult refugees from seven countries (Australia, Canada, Italy, New Zealand, Norway, the UK and the USA). The combined analysis of these surveys suggest about one in ten adult refugees in western countries has post-traumatic stress disorder, about one in 20 has major depression, and about one in 25 has a generalised anxiety disorder. The data also suggests that approximately 50 000 of the 500 000 current refugees living in the USA have post-traumatic stress disorder. However, the authors note that despite focusing on the larger and more rigorous surveys available there was substantial variability in the results of the studies.

Dr Fazel states: “Our overall estimates will need to be used judiciously, in view of the fact that it is difficult to know whether the diverse refugee groups contributing to this analysis were representative of the refugee populations resettled in western countries. Nevertheless, our review suggests that at least several tens of thousands of current refugees in western countries have post-traumatic stress disorder.”

In an accompanying Comment Michael Hollifield (University of Louisville, KY, USA) states: “This information warrants attention by investigators, funding agencies, and service organisations. As world conflicts march on, people will probably continue to be traumatised and displaced. Because resources are scarce, it would be wise to ensure that data collected to make inferences, policies, and services are sound.”

An accompanying Editorial in this week’s issue of The Lancet states that the mental health of refugees and other displaced people is a “major global health problem” that should be addressed by the United Nations new High Commissioner for Refugees.