Table 3.

Results of quality assessment according to the Newcastle-Ottawa Scale.

Author	Selection 1	Selection 2	Selection 3	Selection 4	Comparability A	Comparability B	Exposure 1	Exposure 2	Exposure 3	Scores
Freire, et al. [32]	1	1	1	0	1	1	1	1	0	7
Friedlander, et al. [33]	1	1	1	0	1	0	1	1	0	6
Lee, et al. [34]	1	1	1	0	1	1	1	1	1	8
Rajih, et al. [35]	1	1	1	0	1	0	1	1	0	6