[Significance of regional variations in the prevalence and treatment of depressive disorders and implications for health-care research].

Providing mental health care to patients with depressive disorders is accompanied by deficits in the diagnostics and in the access and adequacy of treatment. Analyzing regional variations in mental health care is of increasing importance in order to detect and explain these supply shortfalls. This paper discusses different explanatory approaches to the regional variations in diagnosed depressive disorders and their treatment. Differences in demographic structures and in patients' attitudes toward mental disorders as well as in their preferences in the choice of treatment may explain regional variation. Furthermore, the number and distribution of care providers between regions may have an effect on variation. In addition to the density and availability of care givers, the quality of care may differ because of factors such as sensitivity to the detection of depressive disorders, coding quality of diagnosis and treatment, guideline-oriented treatment, as well as treatment outcome. Small-area analyses should consider all perspectives in order to understand the complexity of regional variation in the provision of health-care services and to derive recommendations for health-care services that meet people's needs.