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SP12-91: Association of Asthma COPD Overlap to Cost-Related Medication Nonadherence among Older Adults in the United States

Poster Presenter

      Mona Nili

      • PhD Student
      • West Virgina University
        United States


To examine the associations of asthma and COPD overlap (ACO) to cost-related medication nonadherence (CRMN) measures compared to individuals with neither asthma nor COPD (NANC), asthma only, and COPD only among a nationally representative sample of Medicare beneficiaries (age > 65 years) in the US.


We adopted a cross-sectional study design. Multiple years (2006-2013) of the “Cost and Use” and “Access to Care” modules of the Medicare Current Beneficiary Survey were linked with fee-for-service Medicare claims. Multivariable SURVEY logistic regressions examined the associations of ACO to CRMN.


The study sample (N = 37,571) consisted of living community-dwelling older adults continuously enrolled in fee-for-service Medicare for one year. Overall, 3.7% skipped doses of medication, 4.6% took smaller doses of a medicine, 5.2% failed to fill a prescription, and 4.4% delayed filling a prescription due to high cost of their prescriptions. The presence of at least one of these behaviors was used to estimate CRMN, which was 9.7%. The prevalence rates of ACO, asthma only, COPD only, and NANC were 1.5%, 2.3%, 8.8%, and 87.4%, respectively. Older adults with ACO reported greater CRMN compared to NANC (16.0% vs 9.1%). The prevalence of CRMN was 14.5% for asthma only and 13.0% for COPD only patients. Compared to other groups, those with ACO had the highest rates of “skipping doses” (7.5%), “taking smaller doses” (4.4%), “failing to fill a prescription” (6.5%), and “delaying to fill a prescription” (6.9%) due to cost. In the adjusted model that controlled for sociodemographic factors, prescription drug coverage, out-of-pocket (OOP) cost burden [spending more than 10% of income on OOP], and number of chronic conditions, those with ACO were more likely to report any CRMN (Adjusted Odds Ratio (AOR) =1.50; 95% Confidence Interval (CI): 1.14, 1.96). When medication regimen complexity (number of medications) was added to the model, the association of ACO to CRMN was no longer significant. Those with ACO also had the highest medication regimen complexity (average 16.2 drugs) and OOP cost burden (9.3%) compared to all other groups. Both medication regimen complexity (AOR =1.03; 95% CI: 1.02, 1.04) and OOP cost burden (AOR =1.23; 95% CI: 1.04, 1.45) significantly increased the odds of CRMN. AORs for ACO ranged from 0.82 (95% CI: 0.48, 1.38) for “skipping doses” to 1.73 (95% CI: 1.14, 2.61) for “not getting prescribed medicine”. Association of overall CRMN among ACO vs COPD only (p-value = 0.27) and ACO vs. asthma only (p-value= 0.66) were not statistically significant.


One in 10 older Medicare beneficiaries in the US reported some type of CRMN during the study period. Older adults with ACO were more likely to report CRMN compared to NANC older adults; while not directly studied, this likely has significant later in-life morbidity and mortality consequences. The most prevalent type of CRMN was “failing to fill a prescription because of cost” which was significantly more likely to be reported by Medicate beneficiaries with ACO. The associations of ACO to CRMN and specific forms of CRMN were explained by the complexity of medication regimen. ACO adults had the highest disease burden in terms of medication regimen complexity and OOP cost burden. Taken together, all these findings suggest that reducing medication regimen complexity may directly reduce the likelihood of CRMN, and indirectly by alleviating the high OOP cost burden among older adults with ACO. Furthermore, there were no statistically significant differences in the overall CRMN and the specific forms of CRMN among ACO versus COPD only, and ACO versus asthma only. These findings suggest that adults with respiratory conditions are more vulnerable to CRMN. Developing and implementing strategies to improve medication adherence among older adults with respiratory conditions may help to reduce CRMN. As documented in published literature, clinicians and pharmacists can play an important role in reducing medication regimen complexity by counseling patients and/or caregivers, simplifying medication regimens, having more frequent follow-up visits, and conducting more clinic-based or pharmacy-based medication adherence assessments.