Polypharmacy among adults with asthma in the United States, 2005-2020

Background: Asthma is a chronic disease that often requires medication for control. Polypharmacy remains a major issue to medication adherence; however, its evidence among patients with asthma is limited. Objectives: To evaluate the prevalence and determinants of polypharmacy and its associations with asthma control among adults with asthma in the United States. Methods: Data from the 2005-2020 National Health and Nutrition Examination Survey were used to estimate the weighted prevalence of polypharmacy. Selected variables, including demographics, comorbidities, prescription medications, and asthma-related adverse events, were extracted from the National Health and Nutrition Examination Survey. Multivariable logistic regression was conducted to identify factors associated with polypharmacy. Another two sets of multivariable logistic regression models were employed to further assess the association between polypharmacy and asthma-related adverse events: one for asthma attacks and the other for asthma-related emergency department visits. Results: From 2005 to 2020, polypharmacy prevalence was 34.3% and 14.1% among adults with and without asthma, respectively. Characteristics, including older age (P < 0.01), non-Hispanic blacks (P < 0.01), health insurance coverage (P < 0.01), number of health care visits (P < 0.01), and multiple comorbidities (P < 0.01), were associated with polypharmacy. Polypharmacy was associated with increased risks of having asthma attacks (odds ratio, 1.38; 95% CI, 1.08-1.76) and asthma-related emergency department visits (odds ratio, 1.46; 95% CI, 1.09-1.94) among adults with asthma. Among patients taking at least one asthma medication, risks of asthma attacks, and asthma-related emergency department visits did not differ between those with and without polypharmacy. Conclusion: Approximately one in three adults with asthma experienced polypharmacy in the United States. Disparities existed in several characteristics, highlighting the necessity for appropriate care and policies among vulnerable populations. Further validation on the impact of polypharmacy on asthma control is required.