The impact of Medicare Part D on hospitalization rates

To determine whether the change in prescription drug insurance coverage associated with Medicare Part D reduced hospitalization rates for conditions sensitive to drug adherence.

Hospital discharge data from 2005 to 2007 for 23 states, linked with state-level data on drug coverage.

We use a difference-in-difference-in-differences approach, comparing changes in the probability of hospitalization before and after the introduction of the Part D benefit in 2006, for individuals aged 65 and older (versus individuals aged 60-64) in states with low drug coverage in 2005 (versus those in states with high pre-Part D drug coverage).

Hospitalization rates for selected ambulatory care sensitive conditions in 23 states were computed using data from the Census and Health Care Utilization Project. Drug coverage rates were computed using data from several sources.

For the conditions studied, our point estimates suggest that Part D reduced the overall rate of hospitalization by 20.5 per 10,000 (4.1 percent), representing approximately 42,000 admissions, about half of the reduction in admissions over our study period. Conclusions. The increase in drug coverage associated with Medicare Part D had positive effects on the health of elderly Americans, which reduced use of nondrug health care resources.