Payment by episodes of care and comorbidity in Austria: a cross-sectional analysis

BACKGROUND: Austria is currently undergoing a health-care reform, and the issue of integration of care is high on the political agenda. Therefore, payment by episodes of care is a topic of particular interest. This project concentrates on the typical ambulatory services and costs associated with the most important chronic conditions. Since chronic diseases are often combined with other diseases, we specifically try to identify the effect of comorbidity on services and costs. METHODS: We used a full dataset of the Austrian insured population for 2006–07. Robust linear regression was applied to identify the service bundles that are significantly associated with a particular disease. Using these service bundles we calculated disease-specific average ambulatory costs for one episode of care. We accounted for the heterogeneity of needs and costs within the diagnostic groups by identifying split criteria (age and sex). The same methods were applied to assess the effects of comorbidity. FINDINGS: We obtained typical service bundles for a number of common chronic diseases, to give the average costs for an episode of care. As expected, costs were higher for all comorbidities under research than for their single indications. The cost increase was not trivial. First, average costs of comorbidities were in general not the sum of the costs of their individual diseases, and the cost increase varied greatly by the type of comorbidity. Second, the interquartile range of costs increased greatly for comorbid patients, which means that average costs should be interpreted carefully. INTERPRETATION: We have shown that our data and our methods lead to plausible results for a number of chronic conditions. A special focus should be put on people with comorbidities when developing a payment scheme based on episodes of care. FUNDING: Social Health Insurance of Austria.