Inaccurate and misleading meta-analysis of E-cigarettes and population-based diseases.

A random-effects meta-analysis by Glantz et al. recently concluded that the odds of several diseases among current e-cigarette users and smokers were similar. This report details serious deficiencies. We used descriptive analysis methods to assess the studies the authors selected for cardiovascular disease (CVD), stroke and chronic obstructive pulmonary disease (COPD) among e-cigarette users vs. nonusers. We examined all of the source studies for these categories. We demonstrate that the meta-analysis by Glantz et al. had three principal deficits that were avoidable: (1) mixing unjustified and incomprehensible disease outcomes, such as erectile dysfunction with fatal CVDs and influenza with COPD; (2) using survey datasets containing no temporal information about smoking/vaping initiation and disease diagnosis; (3) using longitudinal studies that didn't account for changes in vaping and smoking during follow-up waves. The meta-analysis by Glantz et al. is misleading and inaccurate. The deficits are only apparent to investigators thoroughly experienced with the data from the source studies. We conclude that Glantz et al. failed to meet basic criteria for the quality of source studies; the results of their meta-analysis are invalid.