Impact of Medicare Part D on Pharmaceutical and Medical Utilization in Arizona's Dual Eligible Population

Abstract

Purpose: The purpose of this research was to estimate the impact of Medicare Part D on prescription and medical utilization among Arizona's senior dual eligible population.Methods: Generalized estimating equations were used to analyze changes in utilization among dual eligibles (Arizona Health Care Cost Containment (AHCCCS) beneficiaries between the ages of 66 and 80 as of January 1, 2006) relative to a "comparison" group ineligible for Part D (AHCCCS beneficiaries between the ages of 50 and 62 as of January 1, 2006) for the first two years following the implementation of Part D. Medical and pharmacy claims from AHCCCS from January 1, 2005 to December 31, 2007 were used in this analysis.Results: The dual eligibles and Part D ineligible comparison group were similar in their level and trend of utilization of over-the-counter (OTC) medications and benzodiazepines in the pre-Part D period. Following implementation of Part D, there was an immediate decline in utilization of both OTC medications and benzodiazepines in the dual eligibles relative to the comparison group (p<0.001).Increasing trends for both the dual eligible and comparison group were observed during the pre-Part D period for total prescription utilization, generic medication utilization and antidepressant use. After the implementation of Medicare Part D, utilization of these drug classes was significantly lower among the dual eligibles relative to the comparison group.Trends in physician office visits were similar between the dual eligible group and comparison group for the entire study period. During the first month of Part D, the dual eligibles had a statistically significantly larger increase in physician visits over the previous month relative to the comparison group (p=0.001). The trend in hospitalizations between the two groups significantly differed during the pre-period, precluding meaningful comparisons between the groups for this particular outcome.Conclusion: This study supports the belief that medication use for dual eligible Medicare beneficiaries was disrupted by the transition of outpatient drug benefits from Medicaid to Medicare Part D.