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Comment & Response
June 16, 2020

Home Noninvasive Positive Pressure Ventilation for Chronic Obstructive Pulmonary Disease—Reply

Author Affiliations
  • 1Mayo Clinic Evidence-Based Practice Center, Rochester, Minnesota
JAMA. 2020;323(23):2432-2433. doi:10.1001/jama.2020.6093

In Reply The issue of combining randomized clinical trials and nonrandomized studies in a meta-analysis is a common challenge faced during evidence synthesis. When an abundance of well-done randomized clinical trials does not exist, clinical decision-making has to proceed based on the available evidence. In our systematic review1 about home noninvasive positive pressure ventilation (NIPPV) in COPD, we judged that combining these 2 types of studies was appropriate. For transparency purposes, we presented estimates separately from each study design. When examining the 2 designs, we observed similar trends, consistent results (overlapping CIs of relative estimates of mortality, need for intubation, and hospitalization), and no significant heterogeneity. A methodology study by the Cochrane Collaboration that examined 1583 meta-analyses covering 228 different medical conditions concluded that there was little evidence for significant effect estimate differences between observational studies and randomized clinical trials (ratio of odds ratios, 1.08; 95% CI, 0.96-1.22).2 This should not be interpreted as equating inferences from the 2 designs, and there are many examples of misleading observational studies. It simply means that the totality of evidence needs to be considered when not enough trials are available.