Background: Disease progression in COPD is associated with a decline in exercise performance over time. We assessed whether tiotropium might mitigate this by determining its effect on treadmill endurance time (ET) over 2 years.
Methods: This was a randomized, double-blind, placebo-controlled trial of tiotropium, 18 μg daily, in patients with COPD (FEV1/FVC < 70%; postbronchodilator FEV1 < 65%). The primary end point was ET at 90% of baseline maximum work rate at 96 weeks. Secondary end points were ET at other visits, ET by smoking status, spirometry, and St. George's Respiratory Questionnaire (SGRQ).
Results: A total of 519 patients were randomized (tiotropium 260, placebo 259). Mean age was 65 years, 77% were men, 34% were continuing smokers, and mean FEV1 was 1.25 L (44% predicted). Significantly more patients discontinued placebo (hazard ratio [95% CI], 0.61 [0.44-0.83]). Baseline ET was 301 s (improvement tiotropium/placebo was 13% overall; P = .009; 18% at 48 weeks, P = .004; 13% at 96 weeks, P = .106). In patients with baseline ET between 2 and 10 min (n = 404), improvement at 96 weeks was 19% (P = .04). Current smokers had higher ET with tiotropium vs placebo (P = .018). FEV1/FVC improved with tiotropium (P < .01). SGRQ total score at 96 weeks improved with tiotropium vs placebo by 4.03 units (P = .007).
Conclusions: Treadmill ET was numerically greater over 2 years with tiotropium vs placebo. However, the 96-week difference was not statistically significant. Spirometry and health status also improved with tiotropium over 2 years, attesting to the benefits of long-acting bronchodilator therapy.
Trial registry: ClinicalTrials.gov; No.: NCT00525512; URL: www.clinicaltrials.gov.