Will the Medicare prescription drug benefit eliminate cost barriers for older adults with diabetes mellitus?

OBJECTIVES: To determine the proportion of older people with diabetes mellitus (DM) eligible to enroll in the standard Medicare Part D drug benefit who will exceed the initial $2,250 coverage limit and to determine the effect of hypoglycemic choice on risk of exceeding the coverage limit.

DESIGN: Cross-sectional survey.

SETTING: Nationally representative sample of adults living in United States households participating in the 2001 Medical Expenditure Panel Survey (MEPS).

PARTICIPANTS: Individuals aged 65 and older with a diagnosis of DM eligible to enroll in the standard Medicare Part D drug benefit.

MEASUREMENTS: Prescription medication use and expenditures adjusted to 2006 U.S. dollars as reported in the MEPS prescribed medicine file. Survey-weighted logistic regression models were used to estimate the odds of annual medication expenditures exceeding $2,250, controlling for hypoglycemic type, sociodemographic characteristics, chronic conditions, and health status.

RESULTS: Of the estimated 3.2 million elderly people with DM eligible for the standard drug benefit filling a prescription in 2001, approximately 64% had medication expenditures in excess of $2,250 in 2006 adjusted dollars. The proportion exceeding the initial coverage limit varied by type of hypoglycemic drug used from 60% of those using traditional hypoglycemics to more than 75% of those using novel hypoglycemics. Patients with more comorbidities and poorer health status were at greater risk of exceeding the initial coverage limit.

CONCLUSION: A large proportion of older adults with DM may exceed the initial coverage limit under the standard Medicare Part D drug benefit and incur significant out-of-pocket spending.