Association Between Adherence to Maintenance Medication in Patients with COPD and Acute Exacerbation Occurrence and Cost in China: A Retrospective Cohort Database Study

BACKGROUND: This study aimed to evaluate the association between adherence to maintenance medication (ie, inhaled bronchodilators, inhaled corticosteroid/long-acting beta-2 agonist [ICS/LABA] combinations, and oral therapy) and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and related costs among patients with chronic obstructive pulmonary disease (COPD) in China. PATIENTS AND METHODS: Claims data from the hospitals of a metropolitan city in south China between January 2014 and December 2016 were obtained. Patients with COPD with ≥2 maintenance medication claims during 1 year were included. Adherence was measured by the proportion of days covered (PDC). The interaction of medication class×adherence was considered when building models. RESULTS: A total of 11,708 patients met the inclusion criteria, of whom 10.8% were highly adherent (PDC≥0.8). There were significant interaction effects of drug category on hospitalized AECOPD risk (P≤0.001), hospitalized AECOPD rate (P<0.001), and 1-year hospitalized AECOPD treatment costs (P=0.012). There was a relationship between high adherence and outcomes for ICS/LABA combinations (n=3,419), ie, relative risk of hospitalized AECOPD was reduced by 34.8% (adjusted odds ratio=0.65; 95% confidence interval (CI): 0.54–0.79; P<0.001) while the frequency of hospitalized AECOPD per patient-year was reduced by 24.4% (adjusted rate ratio=0.76; 95% CI: 0.65 to 0.87; P<0.001). Mean 1-year per-patient hospitalized AECOPD costs were reduced by 37.8% (mean difference=−848 USD; 95% CI: −1435–262 USD; P<0.001). Patients taking oral mucolytics and having high adherence had worse AECOPD outcomes than patients with poor adherence. CONCLUSION: High adherence to ICS/LABA maintenance therapy was associated with reduced hospitalized AECOPD rates and costs in Chinese patients with COPD.