Table 1.

Levels of evidence for generic prognostic factors for poor outcome for musculoskeletal pain

Level of evidence	Definition
Strong	Consistent significant findings (≥75%) in studies of high quality, at least 2 studies
Moderate	Consistent significant findings (≥75%) in studies of high and low quality with at least one study of high quality in the direction of consistent significant findings
Weak	Significant findings of only one study of high quality or consistent significant findings (≥75%) in studies of low quality
Inconclusive	Significant findings in less than 3 studies of low quality, or inconsistent significant findings (regardless of quality)