Search strategy formulation for systematic reviews: Issues, challenges and opportunities

•Boolean logic is dominant in the formulation of search strategies for evidence synthesis in professional search, notably healthcare, but in other domains such as law, patents and recruitment.•Boolean methods are complex, time consuming, resource intensive and error prone, and a new approach is required.•Alternative approaches either suffer from the same problems as Boolean methods or introduce further problems such as lack of trust and transparency.•We propose a set of design principles to address the shortcomings of Boolean logic when formulating search strategies for evidence synthesis.