Table 1 Level of evidence for evaluating the importance of intervention studies in the management of neck/upper extremity musculoskeletal conditions.

Level of evidence	Definition
Strong	When provided by generally consistent findings in multiple RCTs of high quality (QR⩾19)
Moderate	When 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).
Some	When 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)
Insufficient	All 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

QR, quality rating; RCTs, randomised controlled trials; WRMD, work‐related musculoskeletal disorders.