Asthma-chronic obstructive pulmonary disease overlap and cost-related medication non-adherence among older adults in the United States

Background Cost-related medication non-adherence (CRN) can negatively impact health outcomes in older adults with asthma and chronic obstructive pulmonary disease (COPD) overlap (ACO) by reducing access and adherence to essential medications. The objective of this study is to examine the association of ACO to any CRN and specific forms of CRN among a nationally representative sample of older (age >= 65 years) adults. Methods We adopted a cross-sectional study design using data from pooled cross-sectional Medicare Current Beneficiary Surveys (MCBS) (2006-2013) and linked fee-for-service Medicare claims. Unadjusted and adjusted logistic regressions that accounted for the complex survey design examined the association of ACO to any CRN and specific forms of CRN. Results Among older adults with ACO, 16% reported any CRN. The most common form of CRN was "failing to get prescription". As compared to older adults with no asthma and no COPD, those with ACO were more likely to report any CRN (adjusted odds ratios [AOR] = 1.50, 95%CI = [1.14, 1.96]) and all forms of CRN. However, when the number of unique medications was added to the model, there were no statistically significant differences in CRN between the two groups. Conclusions Older adults with ACO represent a vulnerable population with increased risk for CRN. Multiple factors can contribute to CRN including: a higher number of prescribed medications, multiple co-morbidities, and cost of therapies. Medication comprehensive review interventions have the potential of reducing the risk of CRN among the older Medicare beneficiaries with ACO.