Treatment of COPD with Long-Acting Bronchodilators: Association Between Early and Longer-Term Clinically Important Improvement

Introduction: This post hoc analysis of the "Early MAXimization of bronchodilation for improving COPD stability" (EMAX) trial investigated whether patients achieving early clinically important improvement (CII) sustained longer-term improvements and lower risk of clinically important deterioration (CID). Methods: Patients were randomized to umeclidinium/vilanterol, umeclidinium, or salmeterol for 24 weeks. The patient-reported outcomes (PROs) Transition Dyspnea Index (TDI), Evaluating Respiratory Symptoms, St George's Respiratory Questionnaire (SGRQ) and COPD Assessment Test (CAT) were assessed. CII, defined as attaining minimum clinically important differences (MCID) in >= 2 PROs, was assessed at Weeks 4, 12 and 24. CID was defined as a deterioration in CAT, SGRQ, TDI by the MCID and/or a moderate/severe exacerbation from Day 30. Results: Of 2425 patients, 50%, 53% and 51% achieved a CII at Weeks 4, 12 and 24, respectively. Patients with a CII at Week 4 versus those without had significantly greater odds of achieving a CII at Weeks 12 and 24 (odds ratio: 5.57 [95% CI: 4.66, 6.66]; 4.09 [95% CI: 3.44, 4.86]). The risk of a CID was higher in patients who did not achieve a CII at Week 4 compared with patients who did (hazard ratio [95% CI]: 2.09 [1.86, 2.34]). Patients treated with umeclidinium/vilanterol versus either monotherapy had significantly greater odds of achieving CII at Weeks 4, 12 and 24. Conclusion: Achieving a CII at Week 4 was associated with longer-term improvement in PROs and a reduced risk of deterioration. Further research is required to investigate the importance of an early response to treatment on the long-term disease course.