Methods resources for authors new to conducting systematic reviews with network meta-analysis: a scoping review

Objectives

To support systematic reviewers new to network meta-analysis (NMA), we (1) identified and described published methods resources for conducting systematic reviews (SRs) with NMA of randomized controlled trials (RCTs); (2) mapped the resources to the typical steps for conducting NMAs; and (3) identified NMA guidance gaps.

Study Design and Setting

We performed a scoping review and comprehensively searched major databases, gray literature sources, and websites for methods resources that described or informed any steps in conducting SRs with NMA to guide review authors, particularly those new to the method. Title, abstract, and full-text screening were conducted independently in duplicate using Covidence. NMA resources were narratively described and tabulated by guidance type, review steps, and topic and mapped to the steps of conducting a systematic review with NMA.

Results

We considered documents in the 2011–2025 date range and included 90; the majority (39%) were published between 2021 and 2025. Most were classified as guides/guidance (29%), methods/methodology (22%), or reviews (27%). We found that the rate of published guidance around most steps of NMA increased or remained stable over time. Most resources for software were guidance for R and Stata. Guidance documents on assumptions and certainty of evidence were abundant (in excess of 13 documents per topic), whereas fewer guidance documents were available on elements of protocol development and presentation of results. We mapped methods resources across steps in conducting SRs with NMA, identifying areas with sparse guidance.

Conclusion

This scoping review provides a comprehensive reference for conducting SRs using NMA, especially for those new to the methods. It highlights the significant increase in guidance since 2011, particularly on evidence certainty and NMA assumptions, and the availability of user-friendly web tools. Future work should focus on advanced NMA guidance and decision tools to aid reviewers in further navigating NMA complexities.