| Study objectives were to: (1) estimate the proportion of Part D enrolled seniors that reached the doughnut hole (DH), when they reached it and how long they stayed in, (2) explore differences in drug use and expenditures between those who reached the DH and those that did not, (3) explore longitudinal, within-person changes in drug use and expenditures between 2006 and 2007, (4) examine factors associated with entry in the DH, and (5) examine the association of the DH with adherence to prescription drug therapy among seniors using anti-hypertensives.;A retrospective, longitudinal, panel design was used to address the first four objectives, whereby, a group of seniors enrolled in Medicare Part D plans in 2006 and 2007 were tracked. A quasi-experimental, pre-post, comparison group design was used to address objective 5. Data for this study were extracted from the pharmacy claims database of a chain of 22 supermarket pharmacies located in one southeastern state. The variables for this study were identified using the Andersen model of health care utilization. Medication adherence was measured as cumulative treatment gaps using the CMG (continuous, multiple-interval measures of medication gaps) methodology. Descriptive statistics, independent- and paired-samples t-tests and logistic regressions were used to used for objective 5.;The results showed that 18% and 3% of Part D enrolled seniors without low-income subsidy (LIS) reached the doughnut hole and catastrophic coverage, respectively, during the first two years after Part D's implementation. Seniors who reached the doughnut hole were older, sicker, had higher drug use and expenditures, but lower generic use rate as compared to those that did not reach the doughnut hole. The RxRisk score, total prescription fills, generic use rate, total drug expenditure, and doughnut hole entry in 2006 were found to be significantly associated with doughnut hole entry in 2007. The study results did not offer a convincing argument that the doughnut hole negatively impacted Part D enrolled seniors' adherence to anti-hypertensive drug therapy. However, the catastrophic coverage likely produced a positive impact on adherence to anti-hypertensive drug regimens. |
