臨床医学に環境・労働の観点を

Methods In this randomized, double-blind trial, we compared 4 years of therapy with either tiotropium or placebo in patients with COPD who were permitted to use all respiratory medications except inhaled anticholinergic drugs. The patients were at least 40 years of age, with a forced expiratory volume in 1 second (FEV₁) of 70% or less after bronchodilation and a ratio of FEV₁ to forced vital capacity (FVC) of 70% or less. Coprimary end points were the rate of decline in the mean FEV₁ before and after bronchodilation beginning on day 30. Secondary end points included measures of FVC, changes in response on St. George's Respiratory Questionnaire (SGRQ), exacerbations of COPD, and mortality.

Results Of a total of 5993 patients (mean age, 65±8 years) with a mean FEV₁ of 1.32±0.44 liters after bronchodilation (48% of predicted value), we randomly assigned 2987 to the tiotropium group and 3006 to the placebo group. Mean absolute improvements in FEV₁ in the tiotropium group were maintained throughout the trial (ranging from 87 to 103 ml before bronchodilation and from 47 to 65 ml after bronchodilation), as compared with the placebo group (P<0.001). After day 30, the differences between the two groups in the rate of decline in the mean FEV₁ before and after bronchodilation were not significant. The mean absolute total score on the SGRQ was improved (lower) in the tiotropium group, as compared with the placebo group, at each time point throughout the 4-year period (ranging from 2.3 to 3.3 units, P<0.001). At 4 years and 30 days, tiotropium was associated with a reduction in the risks of exacerbations, related hospitalizations, and respiratory failure.

Conclusions In patients with COPD, therapy with tiotropium was associated with improvements in lung function, quality of life, and exacerbations during a 4-year period but did not significantly reduce the rate of decline in FEV₁.