Evidence synthesis describes a structured and methodologically appropriate analysis of available evidence to address specific questions. The process ensures a thorough examination of relevant studies whilst recognising and minimising bias. In health technology appraisal, evidence synthesis goes beyond mere aggregation. It involves the integration of diverse types of evidence such as clinical trials, costing and resource use studies, cost effectiveness studies, health outcome studies and other study types.

The specific question to be addressed, available data and the nature of the evidence that is being synthesised often determine the method that will be deployed.