It connects separate randomized-trial comparisons through a shared comparator. For example, evidence comparing intervention A with C can be related to evidence comparing B with C, allowing an estimate for A versus B even without a head-to-head trial. The resulting comparison depends on how well the linked studies support a common evidence network.
Transitivity means that studies can be compared indirectly because their important clinical and methodological features are sufficiently comparable. If differences among patient groups, interventions, or trial conditions affect outcomes, the indirect comparison may be misleading. Assessing this assumption helps determine whether evidence from different comparisons can reasonably contribute to one treatment-effect estimate.
Consistency refers to agreement between direct evidence and indirect evidence addressing the same treatment comparison. When the two sources point to materially different effects, the network may contain conflicting findings or important differences between studies. Examining consistency helps researchers judge how confidently they should interpret pooled estimates and treatment comparisons.
Rankings summarize the relative position of competing interventions, but they do not eliminate uncertainty. An intervention ranked highest may have only a small advantage or imprecise evidence, particularly when comparisons rely heavily on indirect links. Clinicians and guideline developers should therefore consider estimated effects and uncertainty together rather than treating a rank as a definitive recommendation.
Researchers first identify relevant randomized trials and organize their comparisons into a connected evidence network. They then combine direct and indirect results, evaluate transitivity and consistency, and estimate relative treatment effects with their uncertainty. Finally, they may summarize the comparative positions of interventions and identify parts of the network where evidence remains limited or conflicting.
It is particularly useful when several competing healthcare interventions must be considered but trials do not compare every option directly. By bringing the available randomized evidence into one analytical framework, it can support comparisons among alternatives for clinical decisions and guideline development. Its usefulness still depends on a sufficiently connected network and credible underlying assumptions.
The pattern of evidence can show where treatment effects are uncertain, where direct and indirect findings conflict, or where important interventions lack strong comparisons. These results help researchers prioritize future studies and identify potentially valuable head-to-head trials. In this way, the analysis contributes not only to current treatment assessment but also to planning more informative medical research.