Original research is important for informing health care and policy but a critical synthesis of the literature is important1 and should incorporate a full and impartial review “to remove a great deal of rubbish”.2 The early 1990s saw the introduction of the Cochrane Collaboration and a subsequent, steady increase in the number of literature reviews submitted to journals. In part this is because of the need to synthesise the rapidly expanding body of scientific evidence, but is also driven somewhat by author recognition that reviews generally attract a higher citation rate.3 In parallel with the increase in number of reviews, there has also been an expansion in the number of approaches used to undertake these reviews. From the more traditional literature reviews, which were historically the dominant approach, to formal systematic reviews and meta-analysis conducted following established guidelines,[4], [5] there are now more than 14 different review types and associated methodologies.