Table 1.

Criteria adopted to report effect by outcome

– (Negative association)	Review reported statistically significant decrease in outcome measures (meta-analysis). At least half of the studies included in a review reported a significant decrease outcome measure (narrative).
+ (Positive association)	Statistically significant increase in outcome measures (meta-analysis). At least half of the studies included in a review reported a significant increase in outcome measure (narrative).
= (No association)	No significant difference reported (meta-analysis). At least half of the studies included in a review reported no significant difference (narrative). Mixed findings reported in a review with equal or slight difference between number of studies reporting negative, positive or no association (narrative). Low-quality evidence due to issues with bias, follow-up and heterogeneity.