Prevalence, Severity, and Unmet Need for Treatment of Mental Disorders in the World Health Organization World Mental Health Surveys

ALTHOUGH SURVEYS OF MENtal disorders have been carried out since the end of World War II, 3 crossnational comparisons were hampered by inconsistencies in diagnostic methods. This situation changed in the 1980s with the development of the Diagnostic Interview Schedule (DIS), the first psychiatric diagnostic interview designed for use by lay interviewers. The DIS was initially used in the US Epidemiologic Catchment Area (ECA) Study and subsequently in similar surveys carried out in other countries in the 1980s. The results were brought together in the early 1990s in a series of important cross-national articles that showed mental disorders to be highly prevalent. Indeed, prevalence of mental disorder was generally higher than that of any other class of chronic conditions. This was striking in light of research documenting that mental disorders have greater effects on role functioning than many serious chronic physical illnesses. A second generation of cross-national psychiatric surveys was carried out in the 1990s using a more elaborate interview, the World Health Organization (WHO) Composite International Diagnostic Interview (CIDI). Although prevalence varied widely, more than one third of respondents typically met criteria for a lifetime CIDI disorder. Surveyspecific treatment questions showed uniformly that most mental disorders were untreated. Before concluding that unmet need for treatment of mental disorders is a major problem, it is important to recognize that many mental disorders are mild and self-limiting. This was not a focus of the DIS or CIDI surveys, which were designed to estimate prevalence rather than severity. However, the high prevalence estimates in these surveys raised concerns that even the richest of