Table 3.

Best evidence synthesis guidelines

Strong evidence	Provided by consistenta statistically significant findings in outcome measures in at least two high quality RCTsb
Moderate evidence	Provided by statistically significant findings in outcome measures in at least one high quality RCTb or Provided by consistenta, statistically significant findings in outcome measures in at least two medium quality RCTsb
Limited evidence	Provided by statistically significant findings in at least one medium quality RCTb or Provided by consistenta, statistically significant findings in outcome measures in at least two low quality RCTsb
No or insufficient evidence	If results of eligible studies do not meet the criteria for one of the levels of evidence listed above (e.g. no statistically significant findings) or In case of conflicting (statistically significant positive and statistically significant negative) results among RCTs or In case of no eligible studies

Best evidence synthesis guidelines as modified by Dorrestijn et a [50] from the synthesis by van Tulder et al. [45]

Abbreviations: RCT randomized controlled trial

^a Findings are considered consistent if they point in the same direction

^b If the number of studies showing evidence is lower than 50% of the total number of studies found within the same category of methodological quality, we state no evidence