Table 1 Quality criteria
    S1Study provided clearly defined inclusion and exclusion criteria
    S2The stage when initial measures were applied was clearly stated
    S3Measures were applied at an appropriate stage to investigate the research question
    S4The study used representative sampling techniques
    S5Important characteristics of the sample were described
    S6The setting and study site were clearly described
Prognostic indicators
    PI1Clearly defined constructs of what is measured were provided
    PI2Justification of the measures used was given
    PI3The selection of prognostic indicators recognises the multifactorial nature of RTW
    PI4The study used standardised, psychometrically sound instruments for all measures taken
    A1Multivariate techniques were used to adjust for potential confounding variables
    A2The analysis avoided over-fitting the data
    A3Prospective validation in another cohort was performed
    FU1RTW outcome was defined in detail, or measure was of sick leave duration
    FU2The duration of follow-up was greater than or equal to 6 months
    FU3The data were complete for at least 80% of the sample measured at baseline
    FU4Outcome measurements were blinded
  • Requirements to satisfy quality criteria are available from the corresponding author on request. RTW, return to work.