On the appropriate interpretation of evidence: the example of anti-vascular endothelial growth factor for diabetic macular edema

Background: Different network meta-analyses (NMAs) on the same topic result in differences in findings. In this review we investigated network meta-analyses comparing ranibizumab with aflibercept for diabetic macular edema in the hope of illuminating why the differences in findings occurred.Findings: For the binary outcome of best corrected visual acuity, different reviews all agreed on their being no clear difference between the two treatments; while continuous outcomes all favour aflibercept over ranibizumab. We discussed four points of particular concern that are illustrated by five similar NMAs, including: network differences, PICO differences, different data from the same measures of effect, differences in what is truly significant.Conclusions: Closer inspection of each of these reviews shows how the methods, including the searches and analyses all differ but the findings, although presented differently and sometimes interpreted differently, were similar.