Assessment of drug consumption patterns for Medicare Part D patients

To assess the time needed to reach the "doughnut hole" (DH) and catastrophic coverage (CC) periods and to identify prescription drug use patterns among patients eligible for the standard Medicare Part D drug benefit.

Retrospective cohort study.

Data for all prescription drugs dispensed to subjects over age 65 years from November 1, 2006, through February 29, 2008, were obtained from 2 large retail pharmacy chains. Kaplan-Meier estimates of survival curves were used to assess the time to reach the DH and CC thresholds.

Of all 2007 Medicare Part D standard benefit patients in our sample, 18.5% reached the DH, but only 11.6% of those patients reached the CC threshold by the end of 2007. Patients who did not reach the DH in 2007 filled an average of 2.13 prescriptions per month. Patients who reached the DH but did not reach the CC threshold filled an average of 4.86 and 4.40 (9.47% decrease; P <.001) prescriptions per month during the initial coverage and DH periods, respectively. Patients who reached the CC threshold filled an average of 7.59, 8.38, and 7.86 prescriptions per month during the initial coverage, DH, and CC periods, respectively. Similar quantitative patterns were observed for patients with various chronic conditions.

A sizable proportion of standard Medicare Part D drug program beneficiaries reached the DH. Prescription data can help predict the problems beneficiaries enrolled in the standard Medicare Part D drug program might face over time.