Effect of tiotropium on health-related quality of life as a primary efficacy endpoint in COPD
Clinical manifestations of chronic obstructive pulmonary disease (COPD), including airflow limitation, dyspnea, and activity limitation, ultimately lead to impaired health-related quality of life (HRQoL). This 9-month, randomized, double-blind, multicenter study compared the effect of once-daily tiotropium 18 microg and placebo on HRQoL, spirometric parameters, and exacerbations in 554 patients with moderate-to-severe COPD. HRQoL was assessed using the St. George's Respiratory Questionnaire (SGRQ) and the new 8-item Visual Simplified Respiratory Questionnaire (VSRQ), which is currently being validated. The primary efficacy endpoint was the proportion of patients achieving a reduction of at least 4 units in the SGRQ total score at study end (Month 9). Mean +/- SD baseline SGRQ total score was 47.4 +/- 18.1. Significantly more tiotropium-treated patients achieved a reduction of at least 4 units in the SGRQ score vs placebo at study end (59.1% vs 48.2%, respectively; p = 0.029). Tiotropium significantly improved spirometric parameters (forced expiratory volume in 1 second [FEV1]: 0.11 +/- 0.02 L vs 0.01 +/- 0.02 L; between-group difference: 0.10 +/- 0.03 L, p = 0.0001) and reduced exacerbations vs placebo. Maintenance treatment with tiotropium provided significant and clinically relevant improvements in HRQoL, as measured by the SGRQ.