To the Editor: The meta-analysis of inhaled anticholinergics and risk of major adverse cardiovascular events in patients with chronic obstructive pulmonary disease (COPD) by Dr Singh and colleagues1 successfully collected unpublished data and combined it with published studies. However, a 4-year randomized controlled trial involving 5993 patients (Understanding Potential Long-term Impacts on Function With Tiotropium [UPLIFT])2 that was published shortly after this meta-analysis showed no evidence of an increased risk of cardiovascular adverse events with the use of tiotropium. One possible explanation that should be considered for this discordance is publication bias, as might be suggested by a funnel plot.
I am also concerned that there may be errors in data entry and study inclusion in the meta-analysis. The incidence of serious cardiovascular events in the study by Wedzicha et al3 appears to have been 34 in the tiotropium group and 23 in the placebo group; the study by Singh et al used 23 and 13, respectively. The study by Donohue et al4 should have been excluded from the meta-analysis because Brusasco et al5 reported combined results of the study by Donohue and another unpublished study. Inclusion of both seems to have resulted in double counting of the data from Donohue et al.
Financial Disclosures: None reported.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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