Fig. 3.

Star network with six treatments for all available evidence. Comparison of percentage increase in precision (y-axis) for treatment contrast A vs. B from expanding the network of treatments under five separate scenarios over that achieved from a standard, pairwise meta-analysis. Scenarios considered under fixed- and random-effects models. Random-effects models assume “low,” “medium,” and “high” levels of heterogeneity as defined in the main text. The height of each bar denotes the percentage increase in the precision of A vs. B treatment effect estimate from a network meta-analysis (NMA). The horizontal axis reports each increasing level of the network under each of the five scenarios. Read left to right—Each bar relates to the structure of the network in terms of which evidence is included. Scenario 1: “One trial per comparison”: Equal variance across the network. Each comparison XY represents one meta-analysis with variance equal to 1. Scenario 2: “AB weakest link, IC trials weaker”: AB comparison is the “weakest” link, with the comparisons forming ICs being weaker. Scenario 3: “AB weakest link, IC trials strong”: AB comparison is the “weakest” link, with the comparisons forming ICs being stronger. Scenario 4: “AB strongest link, IC trials weaker”: AB comparison is the “strongest” link, with the comparisons forming ICs being weaker. Scenario 5: “AB strongest link, IC trials strong”: AB comparison is the “strongest” link, with the comparisons forming ICs also being strong. IC, indirect comparisons.