Regional variation in healthcare utilization among patients with depression in Germany: a multilevel analysis with PopGrouper-based multimorbidity adjustment

BACKGROUND: Depression is associated with a substantial health and economic burden and shows pronounced regional variation in Germany. While socioeconomic and urban-rural differences in depression prevalence and service use are well documented, less is known about how regional socioeconomic deprivation and urbanization relate to healthcare utilization after accounting for multimorbidity. METHODS: We analyzed nationwide claims data from a large German sickness fund including adults with diagnosed depression (N = 1,083,319). Healthcare utilization in 2023 was measured as healthcare costs, days of sickness absence, any outpatient mental health specialist contact, and outpatient psychotherapy use. Multilevel regression models with individuals nested within 96 spatial planning regions were estimated, adjusting for age, sex, and multimorbidity using the PopGrouper. Regional socioeconomic deprivation was measured using the German Index of Socioeconomic Deprivation, and urbanization was classified as urban, semi-urban, or rural. Proportional variance component analyses quantified explained regional heterogeneity. RESULTS: Higher regional socioeconomic deprivation was significantly associated with more days of sickness absence (adjusted mean: 34.1 days in the least vs. 40.1 days in the most deprived regions) and a lower likelihood of receiving outpatient psychotherapy (17.9% vs. 16.3%). No significant associations were observed between deprivation and healthcare costs or mental health specialist contacts. Urban regions were associated with higher healthcare costs (2,284€ vs. 2,188€) and more frequent mental health specialist contacts (15.6% vs. 13.5%). Overall regional clustering was modest but most pronounced for mental health specialist contacts. CONCLUSION: Regional socioeconomic deprivation is linked to higher sickness absence due to depression. Regional inequalities in access to mental health services are small but largely unexplained by deprivation, urbanization, and multimorbidity.