• chronic obstructive pulmonary disease;
  • Medicare beneficiaries;
  • medication adherence;
  • medication therapy management programmes;
  • spending



The goal of Medicare Part D medication therapy management programmes (MTMPs) is to optimize medication use by beneficiaries. The Centers for Medicare & Medicaid Services require prescription drug plans (PDPs) to consider numbers of chronic medications and conditions, and total Part D spending when targeting beneficiaries for MTMPs. However, there is no explicit evidence base establishing these criteria. The objectives were to examine the associations of Part D spending with medication use and adherence among Medicare beneficiaries with chronic obstructive pulmonary disease (COPD).


This retrospective cross-sectional study used a 5% random sample of Medicare beneficiaries with COPD enrolled in stand-alone PDPs and Medicare Parts A and B in 2006–2007 (n = 72 912). Maintenance medication use and adherence for COPD were measured in three domains: discontinuation, duration of therapy and proportion of days covered.

Key findings

Proportions of beneficiaries using COPD maintenance medications increased with Part D spending, from 33.4% (quintile 1) to 60.5% (quintile 5), after covariant adjustment. Among maintenance medication users, the adjusted proportions of beneficiaries exhibiting better adherence also increased with spending, with the top 20% of spenders having the highest proportion of beneficiaries exhibiting good adherence. Adjusted proportions of beneficiaries discontinuing medications decreased with increased Part D spending.


The Part D MTMP spending criterion (US$4000 in 2007; US$3000 in 2010) may be an inappropriate target for identifying Medicare beneficiaries in need of adherence counselling. Findings suggest higher spenders may have learned healthy adherence behaviours, whereas lower spenders may be prone to discontinue medication and/or demonstrate poor adherence behaviours.