“…10,13,14,17,18,20,21,[31][32][33][34][35] The major methodological issues of the studies were related to confounding factors (n = 7), 10,[13][14][15]19,21,33 and strategies to deal with them (n = 16). 10,12,14,15,[17][18][19][20][21][22]31,32,[35][36][37][38] The study subjects and the setting were not clearly described in nine studies, 10,12,14,17,21,22,33,35,38 and most outcomes were not measured in a valid and reliable way (Appendix 4).…”