[Psychiatric epidemiology and public health medicine. Principles of health service research].

Psychiatric illnesses are among the most common diseases in the general population and contribute significantly to the global disease burden. Psychiatric epidemiology yields scientific estimations of the incidence and prevalence of psychiatric diseases and their associated risk factors. It has also been found that treatment needs are determined by several factors. Health service research analyses treatment needs and whether they are met. The analysis of direct and indirect health care costs and effectiveness are gaining importance in mental health service research.