TABLE 1—

Criteria for Ascertainment of Evidence Level for Best-Evidence Synthesis

Level of Evidence	Criteria for Inclusion in Best Evidence Synthesis
Strong evidence	Generally consistent findings in multiple high-quality cohort studies
Moderate evidence	Generally consistent findings in 1 high-quality cohort study and > 2 high-quality case-control studies
Limited evidence	Generally consistent findings in single cohort study, 1 or 2 case-control studies, or multiple cross-sectional studies
Conflicting evidence	Inconsistent findings in < 75% of the studies
No evidence	No studies found

Note. Adapted from Lievense et al.²⁰