Repeat experience with the doughnut hole in Medicare Part D: when the doughnut hole becomes a tunnel

To describe the proportion of elderly Medicare advantage prescription drug plan (MAPDP) enrollees who meet or exceed the Medicare Part D doughnut hole (DH) entry threshold in 2 consecutive years and which characteristics put them at risk for repeated DH entry.

One cohort of MAPDP enrollees ≥65 years of age with at least 1 month of eligibility in both 2006 and 2007, and a second cohort of enrollees with at least 1 month of eligibility in both 2007 and 2008.

Descriptive statistics were used to compare characteristics of MAPDP enrollees who attained the DH entry threshold in 2 consecutive years with MAPDP enrollees who attained this threshold in only 1 or neither of these years. Adjusted odds ratios of the likelihood of repeatedly entering the DH were obtained using multivariate generalized estimating equations.

The percent of MAPDP enrollees who attained the DH entry threshold in 2 consecutive years was low: 7% of enrollees in the 2006/2007 cohort and 6% of the 2007/2008 cohort. Likelihood of repeatedly entering the DH compared with not entering the DH in 2 consecutive years was significantly higher among MAPDP enrollees with multiple comorbidities and who were ≥74 years of age or female.

A small subset of Medicare beneficiaries with significantly increased risk of repeatedly entering the DH may receive financial protection from closing of the DH as enacted in recent healthcare reform.