BACKGROUND: QVA149 is a once-daily (o.d.) inhaled dual bronchodilator containing a fixed-dose combination of the long-acting β2-agonist indacaterol and the long-acting muscarinic antagonist glycopyrronium for the treatment of COPD. The QUANTIFY study compared QVA149 with a free-dose bronchodilator combination of tiotropium plus formoterol (TIO+FOR) in improving health-related quality of life (HRQoL) of patients with COPD. METHODS: This multicentre, blinded, triple-dummy, parallel-group, non-inferiority study randomised patients aged ≥40 years with moderate-to-severe COPD (post-bronchodilator forced expiratory volume in 1 s (FEV1) ≥30% to <80% predicted) to QVA149 110/50 µg o.d. or TIO 18 µg o.d.+ FOR 12 µg twice daily (1:1) for 26 weeks. The primary endpoint was to demonstrate non-inferiority in HRQoL assessed using St George's Respiratory Questionnaire-COPD (SGRQ-C). The prespecified non-inferiority margin was 4 units. Secondary endpoints included Transition Dyspnoea Index (TDI) score, pre-dose FEV1, forced vital capacity (FVC) and safety. RESULTS: Of the 934 patients randomised (QVA149=476 and TIO+FOR=458), 87.9% completed the study. At week 26, non-inferiority was met for SGRQ-C (QVA149 vs TIO+FOR; difference: -0.69 units; 95% CI -2.31 to 0.92; p=0.399). A significantly higher percentage of patients achieved a clinically relevant ≥1 point improvement in TDI total score with QVA149 (49.6%) versus TIO+FOR (42.4%; p=0.033). QVA149 significantly increased pre-dose FEV1 (+68 mL, 95% CI 37 mL to 100 mL; p<0.001) and FVC (+74 mL, 95% CI 24 mL to 125 mL; p=0.004) compared with TIO+FOR at week 26. The incidence of adverse events was comparable between both treatments (QVA149=43.7% and TIO+FOR=42.6%). CONCLUSIONS: QVA149 is non-inferior to TIO+FOR in improving HRQoL, with clinically meaningful and significant improvements in breathlessness and lung function in patients with COPD. TRIAL REGISTRATION NUMBER: NCT01120717.