Background: Morbidity differences between older members of private and statutory health insurance Germany have rarely been examined. Thus, we aimed at determining these differences in old age. Methods: This study used data from 2 follow-up waves with a 3-year interval from a population-based prospective cohort study (ESTHER study) in Saarland, Germany. Morbidity was assessed by participants' GPs using a generic instrument (Cumulative Illness Rating Scale for Geriatrics). The between estimator was used which exclusively quantifies inter-individual variation. Adjusting for sex and age, we investigated the association between health insurance and morbidity in the main model. In additional models, we adjusted incrementally for the effect of education, family status and income. Results: Regression models not adjusting for income showed that members of private health insurance had a lower morbidity score than members of statutory health insurance. This effect is considerably lower in models adjusting for income, but remained statistically significant (except for men). Conclusion: Observed differences in morbidity between older members of private and statutory health insurance can partly be explained by income differences. Thus, our findings highlight the role of model specification in determining the relation between morbidity and health insurance.
