Figure 3.

Valid network meta-analysis of AB trials (comparing treatment B relative to A) and AC trials (comparing treatment C relative to A). (a) Forest plot of four AB studies and four AC studies. There are no differences in the effect modifier across studies within comparisons and no imbalance in the distribution of the effect modifier between comparisons. Hence, there is no heterogeneity, and no bias in the indirect comparison estimate of C vs B. (b) Forest plot of four AB studies and four AC studies. There are differences in the effect modifier across studies within comparisons, but no imbalance in the distribution of the effect modifier between comparisons. Hence, there is heterogeneity, but no bias in the indirect comparison estimate of C vs B.

Jansen and Naci BMC Medicine 2013 11:159   doi:10.1186/1741-7015-11-159
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