A move to more systematic and transparent approaches in qualitative evidence synthesis: update on a review of published papers

In 2007, the journal Qualitative Research published a review on qualitative evidence syntheses conducted between 1988 and 2004. It reported on the lack of explicit detail regarding methods for searching, appraisal and synthesis, and a lack of emerging consensus on these issues. We present an update of this review for the period 2005-8. Not only has the amount of published qualitative evidence syntheses doubled, but authors have also become more transparent about their searching and critical appraisal procedures. Nevertheless, for the synthesis component of the qualitative reviews, a black box remains between what people claim to use as a synthesis approach and what is actually done in practice. A detailed evaluation of how well authors master their chosen approach could provide important information for developers of particular methods, who seem to succeed in playing the game according to the rules. Clear methodological instructions need to be developed to assist others in applying these synthesis methods.