Commissioners of systematic reviews have differing requirements in terms of breadth of scope, level of analysis required, and timescales available. Planning a review requires consideration of the trade-off between these elements. This applies to both “rapid” reviews and “traditional” reviews with a broad or complex scope.

Approaches for tailoring review methods to commissioner requirements are described. These will be illustrated via case studies of reviews conducted for the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) and Health Services & Delivery Research (HS&DR) programs and other organizations.

An initial step is to discuss with commissioners the trade-off between timescales/resource available, breadth of review scope, and level of analysis; for example, broad overview of many studies or in-depth analysis of a narrower set. Where the evidence base is unknown, one option is to undertake an initial mapping review to assess the volume and type of evidence available. This may assist in refining the selection criteria for the main review, to prioritize the most relevant evidence. In complex reviews, a further option is to develop a conceptual model (logic model) with input from commissioners and experts, to help identify factors which may influence outcomes. This can enable design of focused mini-reviews (not necessarily exhaustive) around each factor. These methodological approaches will be illustrated through three case studies including an HTA on cannabis cessation (trade-off of breadth versus depth); a review of yoga and health (initial mapping to refine selection criteria); and a rapid review of congenital heart disease services (conceptual model to identify areas for focused reviews).

Different approaches may enable discussion with review commissioners around the trade-off between scope, methods and timescales, in order to tailor the review method to best meet commissioner requirements within the timescales available.