Table 1

 Level of evidence for evaluating the importance of intervention studies in the management of neck/upper extremity musculoskeletal conditions

Level of evidenceDefinition
QR, quality rating; RCTs, randomised controlled trials; WRMD, work-related musculoskeletal disorders.
StrongWhen provided by generally consistent findings in multiple RCTs of high quality (QR⩾19)
ModerateWhen provided by generally consistent findings in one RCT of high quality (QR⩾19) and in one or more RCTs of moderate or low quality, or by generally consistent findings in multiple RCTs of moderate quality (QR<19⩾10).
SomeWhen limited evidence, with only one RCT (any quality rating). Some findings of a positive relationship between exposure to the intervention and WRMD in one cohort or case–referent study, or consistent findings in multiple cross-sectional studies, of which at least one study was of medium quality (QR⩾10<14)
InsufficientAll other cases (ie, consistent findings in multiple low-quality (QR<10) cross-sectional studies, or inconsistent findings in multiple studies) or findings of only one cross-sectional study, irrespective of the quality of the study