Evaluating the association between type of prescription drug plan and asthma patients' use of controller medications

Objectives To explore the association between the type of prescription drug plan (PDP) and taking preventive daily asthma medication (controller medication) in patients with poor asthma control of their asthma (defined as taking more than three canisters of short-acting beta-agonists each month). Methods Aretrospective, cross-sectional study using the 2008 Medical Expenditure Panel Survey, a nationally representative sample of the non-institutionalized, civilian US population. Asthma patients were identified by International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code 493. Only those patients that reported use of more than three canisters of rescue inhalers in a 3-month period were included. Based on patients' self-reported use of preventive medications, they were classified as controller drug users and non-users. Descriptive statistics were used to describe the population. A multiple logistic regression model was used to determine odds of controller usage based on type of PDP using demographic characteristics (age, gender, race, ethnicity, income, perceived health status) as confounders. All analysis was done using SAS version 9.1. Key findings Asthma controller drug use was found to be 67% among the study population. The logistic regression analysis showed that patients having Medicare as their PDP were more likely to use controller medications compared with patients with no PDP (odds ratio (OR) 4.58, 95% confidence interval (CI) 1.33-15.77). Higher odds were seen for Medicaid (OR 2.09, CI 0.96-4.54) and Veterans Affairs (OR 1.66, CI 0.16-17.05) prescription beneficiaries too, but the effect was not significant. Conclusions Type of PDP was found to have an effect of utilization of controller drugs among asthma patients. Future research should explore viable plan options that encourage guideline-recommended medication use in asthma patients.