Table 4 Criteria for the quality assessment Study population A Inception cohort  • One point if patients were identified at an early uniform point in the course of their disability e.g., uniform period after

first day of sick leave  • Zero point if it was not clear if an inception cohort was used. B Description of source population  • One point if the source population was described in terms of place of recruitment (for example: Groningen, the Netherlands), time-period of recruitment and sampling frame of source population (for example: occupational health service, organization for social security)  • Zero point if ≤2 features of source population were given. C Description of relevant inclusion and exclusion criteria www.selleckchem.com/products/gs-9973.html  • One point if >2 criteria were formulated  • Zero point if ≤2 criteria were formulated. Follow-up D Follow-up at least 12 months  • One point if the follow-up period was at least 12 months and data were selleck inhibitor provided for this moment in time. E Drop outs/loss to follow-up <20%  • One point if total number of drop outs/loss to follow-up <20% at 12 months. F Information completers versus loss to follow-up/drop outs  • One point if sociodemographic information was presented for selleckchem completers and those lost to follow-up/drop outs at baseline or no loss to follow-up/drop outs. Reasons

for loss to follow-up/drop outs have to be unrelated to the outcome. Loss to follow-up/drop outs: all patients of the assembled

cohort minus the number of patients at the main moment of measurement for the main outcome measure, divided by the total number of patients of the assembled cohort. G Prospective data collection  • One point if a prospective design was used or a historical cohort when the prognostic factors were measured before the outcome was determined  • Zero point if a historical cohort was used, considering prognostic factors at time zero which were not related to the primary research question for which the cohort was created or in case of an ambispective design. Treatment H Treatment in cohort was fully described/standardized  • One point if treatment subsequent to inclusion into cohort was fully described and standardized, or in the case that no treatment was given, Nutlin-3 cost or if multivariate correction for treatment was performed in analysis  • Zero point if different treatment was given and if it was not clear how the outcome was influenced by it, or if it was not clear whether any treatment was given. Prognostic factors I Clinically relevant potential prognostic factors  • One point if in addition to socio-demographic factors (age, gender) at least one other factor of the following was described at baseline:   – health-related factors (e.g., comorbidity like depression, pain anxiety symptoms, pain intensity)   – personal factors (e.g.