Impact of Nonadherence to Inhaled Corticosteroid/LABA Therapy on COPD Exacerbation Rates and Healthcare Costs in a Commercially Insured US Population.

BACKGROUND: Evidence of poor patient adherence to medications for chronic obstructive pulmonary disease (COPD) is well-documented, but its impact on disease exacerbation rates and associated healthcare costs remains unclear.

OBJECTIVE: To assess the association between adherence levels to different inhaled corticosteroid/long-acting ß2-adrenergic agonist (LABA) and COPD exacerbation rates and costs in a commercially insured population.

METHODS: In this observational cohort study, patients with COPD (aged ≥40 years) who were treatment-naïve to inhaled corticosteroid/LABA and were initiating budesonide plus formoterol or fluticasone plus salmeterol between March 1, 2009, and January 31, 2014, were identified in a national representative claims database and were followed for up to 12 months. The date of the first prescription fill for either drug was defined as the index date. Patients were divided into 4 cohorts based on adherence to the index therapy, which was measured by proportion of days covered (PDC); the cohorts were classified as adherent (PDC ≥0.8), mildly nonadherent (0.5 ≤ PDC <0.8), moderately nonadherent (0.3 ≤ PDC <0.5), and highly nonadherent (PDC <0.3). Each nonadherent group was matched in a 1:1 ratio to the adherent group independently, based on prognostically important variables, using propensity score analyses. Exacerbation rates and healthcare costs were analyzed for 1 year after treatment initiation.

RESULTS: During the study period, 13,657 eligible patients with COPD initiated inhaled corticosteroid/LABA; of these, only 1898 (13.9%) patients were adherent during follow-up. Group matching resulted in 1572 patients per group for comparison 1 (adherent vs mildly nonadherent), 1604 patients for comparison 2 (adherent vs moderately nonadherent), and 1755 patients for comparison 3 (adherent vs highly nonadherent). The moderately and highly nonadherent cohorts had higher exacerbation rates than the adherent patients (comparison 2: rate ratio [RR], 1.11; 95% confidence interval [CI], 1.01-1.21; P = .03; comparison 3: RR, 1.11; 95% CI, 1.01-1.21; P = .02). Adherent patients incurred significantly lower healthcare costs than all the nonadherent groups (comparison 1, $22,671 vs $25,545; P <.01; comparison 2, $22,508 vs $24,303; P <.01; comparison 3, $22,460 vs $25,148; P <.01).

CONCLUSIONS: Patients adhered to their inhaled corticosteroid/LABA treatments had lower COPD exacerbation rates and lower healthcare costs compared with the moderately and highly nonadherent patients. Better adherence to maintenance therapies may help to reduce the clinical and economic burdens of COPD.