Table 4

The Critical Appraisal Skills Programme (CASP) checklists results for assessing the methodological quality of the included studies

	Questions	Ali et al 201740	Felkner et al 200738	Golalipour et al 201237	Mulayim et al 200839	Mubarak et al 201436	Ugwuja et al 201035
1	Did the study address a clearly focused issue?	Yes	Yes	Yes	Yes	Yes	Yes
2	Did the authors use an appropriate method to answer their question?	Yes	Yes	Yes	No	Yes	No
3	Were the cases recruited in an acceptable way?	Yes	Yes	Yes	Yes	Yes	Can’t Tell
4	Were the controls selected in an acceptable way?	Yes	Yes	Yes	Yes	Yes	Yes
5	Was the exposure accurately measured to minimise bias?	Can’t Tell	Yes	Yes	Yes	Yes	Can’t Tell
6	Aside from the experimental intervention, were the groups treated equally?	Yes	Can’t Tell	Can’t Tell	Can’t Tell	Can’t Tell	Can’t Tell
7	Have the authors taken account of the potential confounding factors in the design and/or in their analysis?	No	Yes	Yes	No	Yes	No
8	Do you believe the results?	Yes	Yes	Yes	Yes	Yes	Yes
09	Can the results be applied to the local population?	Can’t Tell	Yes	Yes	No	Yes	Yes
10	Do the results of this study fit with other available evidence?	Yes	Yes	Yes	Yes	Yes	Yes
Individual study CASP score		7/10=70%	9/10=90%	9/10=90%	6/10=60%	9/10=90%	5/10=50%