Using U.S. Medicare records to evaluate the indirect health effects on spouses: a case study in Alzheimer’s disease patients

BACKGROUND The burden experienced by spouses of patients with Alzheimer's disease (AD) may have negative consequences for their physical health. We describe here a method for analyzing United States Medicare records to determine the changes in health service use and costs experienced by spouses after their marital partner receives an AD diagnosis. METHODS We initially identified all beneficiaries in the 2001-2005 Medicare 5% sample who had multiple claims listing the ICD-9 diagnostic code for AD, 331.0. The 5% sample includes spouses who share a Medicare account with their marital partners because they lack a sufficient work history for full eligibility on their own. A matched cohort study assessed incremental health costs in the spouses of AD patients versus a control group of spouses of non-AD patients. Longitudinal and cross-sectional analyses tracked the impact of a patient's AD diagnosis on his or her spouse's healthcare costs. RESULTS Our method located 54,593 AD patients of whom 11.5% had spouses identifiable via a shared Medicare account. AD diagnosis in one member of a couple was associated with significantly higher monthly Medicare payments for the other member's healthcare. The spouses' elevated costs commenced 2 to 3 months before their partners' AD diagnosis and persisted over the follow-up period. After 31 months, the cumulative additional Medicare reimbursements totaled a mean $4,600 in the spouses of AD patients. This excess was significant even after accounting for differences in baseline health status between the cohorts. CONCLUSION The study methodology provides a framework for comprehensively evaluating medical costs of both chronically ill patients and their spouses. This method also provides monthly data, which makes possible a longitudinal evaluation of the cost effects of specific health events. The observed correlations provide a coherent demonstration of the interdependence between AD patients' and spouses' health. Future research should examine caregiving burden and other possible factors contributing to the AD spouses' health outcomes. It should also extend the method presented here to evaluations of other chronic diseases of the elderly.