¹ We judged the RCTs by de Buck 2005 and Macedo 2009 to have an overall high risk of bias and the RCT by Allaire 2003 to have an overall low risk of bias. Overall, we judged serious risk of bias to be present and therefore we downgraded the quality of the evidence by one level (‐1).
² The magnitude of the effect on job loss for Allaire 2003 and de Buck 2005 show different relative risks. Allaire 2003 cites a highly significant and large beneficial effect (24 months: RR 0.35, 95% CI 0.18 to 0.68) whereas de Buck 2005 shows no effect (RR 1.05, 95% CI 0.53 to 2.06). The CIs hardly overlap. In addition, considerable statistical heterogeneity is present (I² > 80%). Hence we did not pool the results. As we failed to identify a plausible explanation for the inconsistency, we downgraded the quality of the evidence by two levels (‐2). For the outcomes sickness absenteeism and work functioning, we only had one included RCT. Hence we judged inconsistency as not serious.
³ The number of job loss events was less than 300. The 'threshold rule of thumb value' states that there should be at least 300 events for job loss (dichotomous outcome), and for continuous outcomes there should be at least 400 participants (Higgins 2011). None of the trials fulfilled this criterion, nor did any of the comparisons for any of the outcomes. As the two RCTs reporting on job loss (Allaire 2003; de Buck 2005) were considerably larger than the one very small study (Macedo 2009) we judged the two to have serious imprecision, and so we downgraded the quality of the evidence by just one level (‐1).
⁴ We included both trials with smaller (N = 32 in Macedo 2009) and larger (N = 140 in de Buck 2005, N = 242 in Allaire 2003) sample sizes and both trials with positive (Allaire 2003 ; Macedo 2009) as well as non‐significant results (de Buck 2005). Given the low number of trials we were unable to further analyse publication bias with funnel plots or with statistical tests. Consequently we did not downgrade the quality of the evidence.
⁵ Risk of bias in the Macedo 2009 RCT related in particular to an absence of prognostic comparability and blinding of outcome assessment, which we judged to be sources for serious risk of bias. Consequently we downgraded the quality of the evidence by one level (‐1).
⁶Macedo 2009 included only 32 participants in total. We considered it to have very serious imprecision for the outcomes sickness absenteeism and work functioning. Thus we downgraded the quality of the evidence by two levels (‐2).

⁷ All control groups received either usual care or a minimal intervention such as written information in Allaire 2003.