Disparities in the Appropriateness of Medication Use
Type of DegreePhD Dissertation
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Background: Prior work has identified disparities in the quality and outcomes of health care across socioeconomic subgroups. Medication use may be subject to similar disparities. Objectives: The objectives of this study were to assess the association between 1) potentially inappropriate medication (PIM) use and different disparity parameters (gender, age, race, income, education, and rural or urban areas), 2) PIM use and all-cause mortality and the effect of disparity parameters on this relationship, and 3) anticholinergic drug use and cognitive impairment and the effect of disparity parameters on this relationship. Methods: The study included 30,239 US adults aged ≥ 45 years from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study (recruited 2003-2007). The appropriateness of medication use was measured by the presence of drug-drug interactions (DDIs) measured by the known clinically significant drug interactions list by Ament et al. and use of potentially inappropriate medications (PIMs) in older adults measured by the 2015 Beers Criteria for Potentially Inappropriate Medication Use in Older Adults. Multivariable logistic regressions were used to assess the association of disparity parameters with DDIs and PIM use stratified across prescription only and over-the-counter drugs (aim 1). In addition, Cox proportional hazards time-to-event analysis followed the participants until their death (all-cause) on or before March 31, 2016, iteratively adjusting for disparity parameters and other covariates (aim 2). Furthermore, multivariable logistic regression models assessed disparities in cognitive impairment with the use of anticholinergic drugs (ACHs), the largest subset of PIMs in the Beers Criteria, iteratively adjusting for disparity parameters and other covariates (aim 3). Results: High prevalence of PIM use (87% of the participants) was observed in our study. White females compared with white males and black males compared with white males had higher odds of receiving prescription-only PIMs. We also found that females compared with males, blacks compared with whites, and individuals with lower income, lower education, and residing in rural areas had higher PIM prevalence. Additionally, we observed that PIM use increased the risk of all-cause mortality among whites. Higher PIM use was independently associated with higher mortality risks. Conclusion: Demographic and socioeconomic disparities in PIM use and DDIs exist. Our fully adjusted analyses also suggest the presence of disparities in all-cause mortality with PIM use. We also observed demographic and socioeconomic disparities in ACH use and in cognitive impairment, individually. Future studies should seek to better understand factors contributing to the disparities in order to guide development of interventions.