Table 2: Results from the Downs and Black quality assessment.

Study 1) Is the hypothesis/aim/objective of the study clearly described? 2) Are the main outcomes to be measured clearly described in the Introduction or methods section? 3) Are the characteristics of the patients included in the study clearly described? 4) Are the interventions of interest clearly described? 6) Are the main findings of the study clearly described? 7) Does the study provide estimates of the random variability in the data for the main outcomes? 11) Were the subjects asked to participate in the study representative of the entire population from which they were recruited? 12) Were those subjects who were prepared to participate representative of the entire population from which they were recruited? 16) If any of the results of the study were based on "data dredging", was this made clear? 18) Were the statistical tests used to assess the main outcomes appropriate? 20) Were the main outcome measures used accurate (valid and reliable)? 25) Was there adequate adjustment for confounding in the analyses from which the main findings were drawn? Quality Index Score (out of 12) Quality Index %
Rendos, et al. [9] 1 1 1 1 1 0 1 1 1 1 1 0 10 83
Chapman, et al. [10] 1 1 1 1 1 0 1 1 1 1 1 0 10 83
Walsh, et al. [11] 0 1 1 1 1 0 1 1 1 1 1 0 9 75
Chapman, et al. [12] 0 1 1 1 1 0 1 1 1 1 1 0 9 75
Bonacci, et al. [6] 1 1 0 1 1 0 1 1 1 1 1 0 9 75
Connick, et al. [5] 1 1 1 1 1 0 0 0 1 1 1 0 8 67
Bonacci, et al. [13] 1 1 0 1 1 0 0 0 1 1 1 0 7 58
Gottschall, et al. [14] 1 1 0 1 1 0 0 0 1 1 1 0 7 58
Bonacci, et al. [15] 0 0 1 1 1 0 0 0 1 1 1 0 6 50
Poklikuha, et al. [16] 0 0 1 1 1 0 0 0 1 1 1 0 5 42
Bonacci, et al. [17] 0 0 0 1 1 0 0 0 1 1 1 0 5 42