Table 3

Levels of evidence for the overall quality of measurement properties per instrument across all included studies20–23

LevelRatingCriteria
Strong+++ or −−−Consistent findings in multiple studies of good methodological quality OR in one study of excellent methodological quality
Moderate++ or −−Consistent findings in multiple studies of fair methodological quality OR in one study of good methodological quality
Limited+ or –One study of fair methodological quality
Conflicting±Conflicting findings
Unknown?No studies or only studies of poor methodological quality
  • +, positive result; –, negative result.