The yield from national surveys of mental health.

At least 21 countries have now carried out national surveys of mental health under the aegis of the World Health Organization's World Mental Health Surveys. This has meant interviewing some 157 000 people in their homes. The countries are as varied as Australia, China, Iran, six continental European nations, Nigeria, the UK and the USA (Andrews , 2001; Demyttenaere , 2004; Mohammadi , 2005). It is therefore timely to consider what this very large body of information has yielded and to what use it can be put, especially in relation to the costs and human resources expended in a field where unmet need is so conspicuous.