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. 2014 Jul 21;2014(7):CD009285. doi: 10.1002/14651858.CD009285.pub3

Summary of findings for the main comparison. Tiotropium versus placebo for chronic obstructive pulmonary disease.

Tiotropium versus placebo for chronic obstructive pulmonary disease
Patient or population: people with COPD who have smoked for ≥ 10 pack‐years
 Settings: community
 Intervention: tiotropium
Comparison: placebo
Outcomes Illustrative comparative risks* (95% CI) Relative effect
 (95% CI) No of Participants
 (studies) Quality of the evidence
 (GRADE) Comments
Assumed risk Corresponding risk
Placebo Tiotropium
Quality of life (SGRQ)
Scale 0 to 100, where 100
 represents worst possible health status and 0 indicates best possible health status
Follow‐up: 3 to 48 months
See comment See comment MD ‐2.89 
 (‐3.35 to ‐2.44) 13,034
 (9 studies) ⊕⊕⊕⊕
 high Several studies did not report results for individual treatment groups and reported MD between the groups only. The accepted threshold for a clinically significant difference is ‐4 units
Number of patients with a clinically significant improvement (≥ 4 units) in quality of life (SGRQ) 
 Follow‐up: 3 to 48 months 389 per 1000 492 per 1000 
 (468 to 517) OR 1.52
(1.38 to 1.68)
11,672
 (9 studies) ⊕⊕⊕⊕
 high  
Number of patients with a clinically significant worsening (≥ 4 units) in quality of life (SGRQ) 
 Follow‐up: 3 to 48 months 348 per 1000 257 per 1000 
 (239 to 277) OR 0.65
(0.59 to 0.72)
11,672
 (9 studies) ⊕⊕⊕⊕
 high  
Number of patients with one or more exacerbations 
 Follow‐up: 3 to 48 months 442 per 1000 382 per 1000 
 (357 to 408) OR 0.78 
 (0.70 to 0.87) 23,309
 (22 studies) ⊕⊕⊕⊕
 high1  
Number of patients with one or more exacerbations requiring hospitalisation 
 Follow‐up: 3 to 48 months 131 per 1000 113 per 1000 
 (98 to 131) OR 0.85 
 (0.72 to 1.00) 22,852
 (21 studies) ⊕⊕⊕⊖
 moderate2  
Number of patients with one or more hospitalisations for any cause 
 Follow‐up: 3 to 48 months 234 per 1000 234 per 1000 
 (212 to 257) OR 1.00 
 (0.88 to 1.13) 20,963
 (19 studies) ⊕⊕⊕⊖
 moderate2  
Mortality 
 Follow‐up: 3 to 48 months 49 per 1000 48 per 1000 
 (43 to 54) OR 0.98 
 (0.86 to 1.11) 23,309
 (22 studies) ⊕⊕⊕⊖
 moderate2  
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
 CI: Confidence interval; MD: Mean difference; RD: Risk difference; OR: Odds ratio; SGRQ: St George's Respiratory Questionnaire
GRADE Working Group grades of evidence
 High quality: Further research is very unlikely to change our confidence in the estimate of effect.
 Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
 Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
 Very low quality: We are very uncertain about the estimate.

1 Although there was moderate unexplained heterogeneity between the study results (I2 = 51%), this was deemed not to affect the direction of the effect or have a large effect on the size of the effect.

2 The number of participants and/or events were low, leading to wide CIs and imprecision in the result.