Regional Differences in Morbidity Across Germany: A Cross-State Comparison Using Hospital Data

OBJECTIVES: The aim of the study was to investigate the presence of regional differences in morbidity across geographic regions in Germany.

METHODS: Retrospective hospital data from the German Institute for the Hospital Remuneration System (InEK) from 2019 to 2023 were used. Aggregated data were investigated at federal state level and stratified by geographic region (East, Northwest, Southwest). Primary and secondary inpatient diagnoses were utilized. Comorbidity scores (updated Charlson Comorbidity Index [uCCI]) per 1,000 capita were calculated based on diagnosis data (4‑digit ICD-10-GM codes). Significance of regional differences was assessed with a negative binomial mixed-model. To determine the effect strength, risk ratios (RR) adjusted for average age, gender distribution, city state status, and gross domestic product (GDP) per capita were calculated. Data for demographics and other covariates were obtained from the Federal Statistical Office (DESTATIS).

RESULTS: Across all years, the East had the highest comorbidity scores, ranging from 381.1 in 2019 to 327.7 in 2023. Lowest comorbidity scores were observed for the Southwest, ranging from 277.4 in 2019 to 231.8 in 2023. A downward trend was observed over time. With an adjusted RR of 0.81 (95%-CI: 0.69-0.95), the Northwest had significantly lower scores compared to the East (z=-2.59, p=0.009). Similarly, the Southwest had significantly lower scores (z=-3.19, p=0.001) and an adjusted RR of 0.70 (95%-CI: 0.56-0.87).

CONCLUSIONS: Although attempts have been made to equalize regional differences in the 35 years since the reunification of the Federal Republic of Germany and the German Democratic Republic, Eastern Germany still lags behind other regions of the country. Based on hospital data, Eastern Germany shows significantly higher morbidity compared to the Northwest and Southwest of Germany. Respective differences and the associated burden of disease must be considered when refining the healthcare system and inpatient capacities.