Adherence to Inhaled Medications and its Effect on Healthcare Utilization and Costs Among High-Grade Chronic Obstructive Pulmonary Disease Patients.

Abstract

Adherence to inhaled medication regimens affects chronic obstructive pulmonary disease (COPD) prognosis and quality of life, and reduces the use of healthcare services, resulting in cost savings. To examine the effects of adherence to inhaled medication regimens on healthcare utilization and costs in high-grade COPD patients. We performed an observational retrospective cohort study using a longitudinal data set from the Korean Health Insurance Review and Assessment Service (2008-2013) containing healthcare services' information for 50 million beneficiaries. The study population was high-grade COPD patients. "Adherent" was defined as a patient attaining a medication possession ratio (MPR)≥80%. We estimated the effects of adherence on the use of intensive care units (ICUs) and emergency rooms (ERs) using a multivariate logistic regression, and estimated the effects on costs (all-cause and COPD-related) using a generalized linear model, with adjustment for patient sociodemographic characteristics, health status, and comorbidities. Of 9086 high-grade COPD patients, adherence declined from 34.7 to 22.3% over 4years. Adherence was inversely associated with use of ICUs and costs, and this association got stronger as the adherence period lengthened. Over the 4-year period, the adherent group had a lower likelihood of using ICUs [odds ratio (OR)=0.74, 95% confidence interval (CI) 0.60-0.91] than the non-adherent group. Similarly, the adherent group had a 10.4% lower all-cause cost (p<0.001) and an 11.7% lower COPD-related cost (p<0.0001) versus the non-adherent group. Adherence reduces healthcare utilization and costs, so adherence is not only clinically effective but also economically efficient. However, less than one-quarter of this population remained adherent over the 4-year period, suggesting that strategies are needed to improve adherence.