Background: This study explores spirometry quality and reproducibility in the Understanding Potential Long-term Impacts on Function with Tiotropium (UPLIFT(®)) trial.
Methods: Four-year, randomized, double-blind, placebo-controlled, multicenter trial in 5993 patients with chronic obstructive pulmonary disease. Within-test variability of pre- and post-bronchodilator forced expiratory volume in 1 s (FEV(1)) was compared across study visits. Between-test variability of best pre- or post-FEV(1) values between two visits 6 months apart was compared at the start, middle and end of the trial.
Results: Three or more acceptable maneuvers were obtained in 93% of visits. Within-test variability of pre- and post-FEV(1) (mean standard deviation: 0.092 and 0.098 L) decreased during the trial. Between-test variability also decreased: pre-FEV(1) (visit 3-5 = 0.141 ± 0.138 L; visit 9-11 = 0.129 ± 0.121 L; visit 17-19 = 0.121 ± 0.122 L); post-FEV(1) (0.139 ± 0.140, 0.126 ± 0.123, 0.121 ± 0.122 L, respectively), and was dependent on age, sex, smoking status and disease stage, but not on bronchodilator response or study treatment.
Conclusion: Spirometry quality in UPLIFT(®) was good and improved during the trial. Between-test variability across patient subgroups suggests that relevant cut-offs for individual disease monitoring are difficult to establish.
Trial registration number: NCT00144339.
Keywords: Forced expiratory volume; Forced vital capacity; Placebo-controlled; Tiotropium.
Copyright © 2013 Elsevier Ltd. All rights reserved.