The NICE COVID-19 search strategy for Ovid MEDLINE and Embase: developing and maintaining a strategy to support rapid guidelines

Introduction: The United Kingdom's (UK) National Institute for Health and Care Excellence (NICE) needs access to evidence on COVID-19 to develop rapid guidelines for healthcare professionals. This paper reports on how the NICE COVID-19 search strategy for identifying references in Ovid MEDLINE and Embase has been developed and maintained. Methods Each free-text line from the June 2020 version of the NICE COVID-19 search strategy was categorised as Critical, High, Medium, Low or Zero priority, according to the number of results and their relevance to NICE. Five search options were devised and tested by combining them with a search for drug treatments. The two prioritised options were compared to the COVID-19 Limit available in Ovid. New subject headings were tested and added. The selected option was refined to make the strategy simpler to use. Results The updated strategy combines free-text terms, categorised as Critical, High and Medium priority for NICE, with appropriate subject headings. Discussion The paper describes the challenges of maintaining a search strategy during the COVID-19 pandemic, as terminology continues to evolve. Conclusions A search strategy for identifying COVID-19 references, within the remit of NICE, has been developed. The recommended strategy could be considered for validation at an appropriate point in the pandemic. It is hoped that understanding how NICE has maintained its COVID-19 strategy will encourage further discussion on the challenges.