Effect of tiotropium on lung function decline in early-stage of chronic obstructive pulmonary disease patients: propensity score-matched analysis of real-world data

BACKGROUND: Tiotropium failed to slow the annual rate of forced expiratory volume in 1 second (FEV(1)) decline in chronic obstructive pulmonary disease (COPD) patients with <70% predicted FEV(1). However, the rate of FEV(1) decline is known to be faster at early stages, which suggests that the effects of tiotropium may be more prominent in early-stage of COPD patients. The aim of this study was to test the hypothesis that tiotropium modifies the rate of FEV(1) decline in COPD patients with an FEV(1)≥70%. METHODS: We retrospectively reviewed the records of COPD patients diagnosed between January 1, 2004, and July 31, 2012, at Seoul National University Hospital, Seoul National University Bundang Hospital, and Seoul Metropolitan Government-Seoul National University Boramae Medical Center. The inclusion criteria were as follows: age ≥40 years, postbron-chodilator (BD) FEV(1)≥70% of predicted and FEV(1)/FVC (forced vital capacity) <0.70, and spirometry more than two times at certain times of the year. Conversely, the exclusion criteria were as follows: asthma, lung cancer, pulmonary tuberculosis, pulmonary resection, or long-term use of a short-acting muscarinic antagonist. The annual lung function decline in patients using tiotropium was compared with that in patients not using the drug. RESULTS: Of the 587 patients enrolled in the study, 257 took tiotropium. Following propensity score matching, 404 patients were included in the analysis. The mean annual rate of post-BD FEV(1) decline was 23.9 (tiotropium) and 22.5 (control) mL/yr (P=0.86); corresponding pre-BD values were 30.4 and 21.9 mL/yr (P=0.31), respectively. Mean annual rate of post-BD FVC decline was 55.1 (tiotropium) and 43.5 (control) mL/yr (P=0.33); corresponding pre-BD values were 37.1 and 33.3 mL/yr (P=0.13). CONCLUSION: Therefore, tiotropium does not reduce the rate of lung function decline in COPD patients with FEV(1)≥70%.