Table 1.

Results of the quality assessment of studies by downs and black scale

Ref.	Criteria checklist downs and black												Total
	1	2	3	6	7	9	10	11	12	16	18	20	(No. of √)
Almeida et al[15]	√	X	√	X	√	√	√	?	?	√	√	√	8
Cheng et al[16]	√	√	√	√	√	√	√	?	?	√	√	√	10
Fortin et al[17]	√	√	√	√	√	√	√	?	?	√	√	√	10
Annetts et al[18]	√	√	√	√	√	√	√	X	X	√	√	√	10
Weber et al[19]	√	√	√	√	X	?	√	X	X	√	√	√	8
Edmondston et al[20]	√	√	√	√	√	√	√	X	X	√	√	√	10
Milanesi et al[21]	√	√	√	√	√	√	√	?	?	√	√	√	10
de Oliveira Pezzan et al[22]	√	√	√	√	√	√	√	?	?	√	√	√	10
Yang et al[23]	√	√	√	√	?	√	√	?	?	√	√	√	9
Silveira et al[24]	√	√	√	√	√	√	√	?	?	√	√	√	10
Iunes et al[25]	√	√	√	√	X	√	√	?	?	√	√	√	9
Belli et al[26]	√	√	√	√	√	√	X	√	√	√	√	√	11
Chase et al[27]	√	√	√	√	√	?	√	√	√	√	√	?	10
Iunes et al[12]	√	√	√	√	√	√	√	X	X	√	√	√	10
Iunes et al[28]	√	√	√	√	√	√	√	?	?	√	√	√	10
Penha et al[29]	√	√	√	√	√	√	√	√	√	√	√	√	12
Rodrigues et al[30]	√	√	√	√	√	√	√	X	X	√	√	√	10
Straker et al[31]	√	√	√	√	√	√	√	√	√	√	√	√	12
Iunes et all[32]	√	√	√	√	X	√	√	X	X	√	√	√	9
Smith et al[3]	√	√	X	√	√	√	√	?	?	√	√	√	9
Yi et al[33]	√	√	√	√	√	√	√	?	?	√	√	√	10
Min et al[34]	X	√	√	√	√	√	?	?	?	√	?	√	7
Straker et al[35]	√	√	√	√	√	√	√	√	√	√	√	?	11
Szopa et al[36]	√	√	√	√	√	X	√	?	?	√	?	√	8
Amsters et al[37]	√	√	√	√	√	√	X	?	?	√	?	X	7
O’Sullivan et al[38]	√	√	√	√	√	√	√	?	?	√	√	√	10
Milosavljevic et al[39]	√	√	√	√	√	√	√	√	√	√	√	√	12
Munhoz et al[40]	√	√	√	√	√	√	√	√	√	√	√	√	12
Lima et al[41]	√	√	√	√	X	?	√	?	?	√	√	?	7
Raine et al[42]	√	√	√	X	√	X	√	X	X	√	√	√	8
Christie et al[43]	√	√	√	√	√	√	√	?	?	√	√	√	10
Watson et al[44]	√	?	√	X	√	√	X	?	?	√	√	√	7
Raine et al[45]	√	√	√	√	√	√	√	X	X	√	√	√	10
Mitchell et al[46]	X	√	√	√	√	√	?	?	?	√	?	X	6
Dieck et al[47]	√	√	√	√	X	?	√	?	?	√	√	√	8

Downs and black criteria: (1) Is the hypothesis/objective clearly described? (2) Are the main results to be measured clearly described in the Introduction or Materials and Methods? (3) Were the characteristics of the patients included clearly described? (6) Are the main findings of the study clearly described? (7) Does the study estimate the random variability in the data of the main results? (9) Were the characteristics of the lost patients described in the study? (10) Were the true probability values reported for the main results? (11) Are the subjects asked to participate in the study representative of the entire population where they were recruited? (12) Are the subjects recruited to participate in the study representative of the entire population where they were recruited? (16) If any of the results of the study were based on “data dredging”, was it clear? (18) Were statistical tests used to assess the main results appropriate? (20) Were the main results evaluated accurate (valid and reliable)? Responses to the criteria: √: Yes; X: No; ?: Unable to determine.