What is a ‘complex systematic review’? Criteria, definition, and examples

Systematic reviews involve systematically searching for all available evidence, appraising the quality of the included studies, and synthesising the evidence into a usable form. They contribute to the pool of best available evidence, translating research into practice, and are powerful tools for clinicians, policymakers, and patients.1 To be useful for decision making, systematic reviews need to include high-quality evidence. However, there...