Inconsistency – Unexplained heterogeneity of results. Scored
‘‘no’’ where heterogeneity was not present, or where it was
present but explored, and scored ‘‘serious’’ where heterogeneity
was clearly present (stated by the reviewers or clearly observable in the forest plot) but not explored or explained, or where not reported, or where only 1 study was found (as homogeneity could not be corroborated).