Incidence of Exacerbations Among Chronic Obstructive Pulmonary Disease (COPD) Patients Receiving Nebulized Long-Acting β2-Agonists (LABAs)

Charles Maken, MBA; Yaozhu Chen; Vamsi Bollu, MBA

PURPOSE: COPD exacerbations can significantly worsen patients' disease-related morbidity and mortality. Arformoterol and formoterol are the only two FDA approved nebulized LABAs for COPD maintenance. The real-world comparative evidence on their impact on COPD exacerbations is lacking.

METHODS: This retrospective cohort study used data from a large claims database. Included patients were: age≥35 years, with ≥2 fills of arformoterol or formoterol between 01/01/2008-12/31/2012 (first nebulized LABA as index), COPD diagnosis (ICD-9-CM 491.x, 492.x, 496.x) on ≥2 outpatient or ≥1 inpatient claims, continuous enrollment 180-day pre- and 360-day post-index, and no nebulized LABA or asthma diagnosis during the pre-index period. Adherence to index drug was computed using proportion of days covered (PDC) in the 360-day post-index. To assess the impact of treatment on study outcome, the study was limited to those adherent or partially adherent (A/PA, PDC≥60%) to their index drug. Exacerbations were measured by COPD-related hospitalizations, emergency room visits, or office visits accompanied by antibiotics or corticosteroids fills within 30 days. Chi-square and t-test were used to compare the two cohorts (alpha=0.05). A Cox proportional hazards model estimated the risk of exacerbations as a function of index nebulized LABA and demographic and clinical characteristics.

RESULTS: A total of 417 (arformoterol=274, formoterol=143) patients (mean age=70.7, 45% females) were included. Compared to formoterol users, arformoterol users had lower pre-index COPD exacerbations (57% vs. 69%), lower pre-index use of oral antibiotics (62% vs. 73%) and nebulized SABA (33% vs. 47%), higher Charlson Comorbidity Index score (mean 2.6 vs. 2.3), all p<0.05. Patients receiving arformoterol had lower post-index incidence of exacerbations (70.4% vs. 80.4%, p<0.05), and fewer post-index exacerbations (mean 3.1 vs. 3.8, p=0.099). After controlling for patients’ baseline demographics, pre-index COPD-related comorbidities and healthcare use, arformoterol users had a 19% marginally lower risk of exacerbations than formoterol users (HR 0.81, 95% CI 0.64-1.03).

CONCLUSIONS: In this study focusing on A/PA users, COPD patients on arformoterol were found to have a lower incidence of exacerbations after controlling for other confounders, compared to those on formoterol.

Chest. 2014;146(4_Meeting