The NRSMG does not recommend limiting search strategies by index terms relating to study design. However, review authors may wish to contact researchers who have reported some success in developing efficient search strategies for NRS (see Section 13.3.1) and other review authors who have carried out Cochrane reviews (or other systematic reviews) of NRS for review questions similar to their own.
When searching for NRS, review authors are recommended to search for studies investigating all effects of an intervention and not to limit search strategies to specific outcomes (Chapter 6, Section 6.4). When searching for NRS of specific rare or long-term (usually adverse or unintended) outcomes of an intervention, including free text and MeSH terms for specific outcomes in the search strategy may be justified. Members of the Adverse Effects Methods Group have experience of doing this (see Chapter 14, Section 14.5).
Review authors should check with their CRG editors whether the CRG-specific register includes studies with particular study design features and should seek the advice of information retrieval experts within the CRG and in the Information Retrieval Methods Group (see Chapter 6, Box 6.7.a).