Read either the article by Otte im Kampe et al. (2016) http://dx.doi.org/10.1136/bmjopen-2015-010399

comment on the application of their reported findings to the relevant populations as you relate to its (i) search strategy (robustness and transparency), and (ii) synthesis of the findings (bias and heterogeneity of the studies). In other words, do you think their search strategy and synthesis of the findings were appropriate? Why or why not? [4 marks]