Effects of reaching the drug benefit threshold on Medicare members' healthcare utilization during the first year of Medicare Part D.

BACKGROUND: Information on the effects of reaching the Medicare Part D standard drug benefit threshold is limited.

OBJECTIVES: Describe and compare pre- and post-threshold healthcare and medication utilization of Medicare beneficiaries who reach threshold relative to those who do not reach threshold and those who do not have a threshold.

RESEARCH DESIGN: Retrospective study of 21,349 beneficiaries enrolled into a Medicare Direct Pay Plan with a standard threshold and 9088 Part D-eligible beneficiaries without a threshold. We used Poisson methods to compare utilization and conditional Poisson models to assess utilization changes. Medication adherence was determined.

RESULTS: The 1237 (6%) beneficiaries who reached threshold were older, had greater morbidity, received more medications, and had more medical office visits (all P < 0.001) than beneficiaries who did not reach threshold. After adjustment, those who reached threshold had greater incidences of inpatient [risk ratio (IRR) = 1.85; 95% confidence interval (CI): 1.64-2.09] and emergency department use (IRR = 1.60; 95% CI: 1.40-1.83). After reaching threshold, primary care visits decreased compared with the same time frame in 2005 for those who reached threshold (IRR = 0.86; 95% CI: 0.79-0.93) and a matched group with no threshold (IRR = 0.88; 95% CI: 0.84-0.92). Adherence to chronic medications declined over time in both groups, but adherence decline was greater for beneficiaries who reached threshold.

CONCLUSIONS: Beneficiaries who reach threshold are older, have more morbidity, and use more medications. Although medication adherence declines after reaching threshold, its association with changes in other healthcare utilization is not clear.