Using income-related inequality measures to evaluate the distributional impact of changes in health insurance coverage: the example of Medicare Part D
This article demonstrates how income-related inequality measures can be used to estimate the impact of health system changes on inequalities in health expenditure, and provides a guide for future evaluations.
The study evaluated the impact of the Medicare Part D policy in the United States, which increased access to prescription medications for Medicare beneficiaries from 2006, on income-related inequality in pharmaceutical expenditure. Through a difference-in-differences analysis, the study investigated the change in inequality in drug expenditures, as measured using the concentration index and generalised concentration index, between the elderly (over 65 years) and near-elderly (54–63 years) pre- and post-implementation of Medicare Part D. Study findings indicated that the implementation of Medicare Part D significantly reduced the degree of pro-poorness in public drug expenditure. The poor gained less of the increased public drug expenditure than the rich in both relative and absolute terms. However, these effects appear to have been short-lived, with a return to prevailing trends in inequality of expenditure several years following the start of Part D.
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