8. Detailed QUIPS risk of bias assessments by study.
| Study ID: Beneciuk 2017 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 63%; non‐participants not adequately described |
| Study Attrition | Moderate | 80% follow‐up at 4 months, 76% at 1 year; dropouts were younger |
| Prognostic Factor Measurement | Moderate | PF with good face validity (expectations of recovery; 0 ‐ 10); data driven cut‐points used to categorise continuous measure of PF |
| Outcome Measurement | Low | Clinical rationale provided for categorisation of continuous outcome (RMDQ) |
| Study Confounding | High | Univariate only for PF association with outcome (TEM analysis) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Besen 2015 | ||
| Domain | Risk of bias level | Support for Judgement |
| Study Participation | Moderate | Participation rate unclear (volunteers); selection criteria and baseline sample adequately described |
| Study Attrition | Moderate | 72% follow‐up at 3 months; no reasons for loss, respondents had more organisational support, which may bias results |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (RTW confidence, and RTW self‐efficacy scale) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS, Quebec Back Pain Disability scale); work status, work modifications, duration of absences self‐reported with unclear measurement properties |
| Study Confounding | Low | Adequate adjustment (education, fear avoidance, catastrophising, race, ethnicity, income, organisational support, co‐worker support, pain) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results; conceptual framework for inclusion of covariates |
| Study ID: Bishop 2015 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate 38%; non‐participants not adequately described |
| Study Attrition | Moderate | 87% follow‐up; no information on attempts to collect outcome information from dropouts; dropouts were younger |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (subscale of the Credibility Expectancy Questionnaire) |
| Outcome Measurement | Low | Valid and reliable measure of outcome (RMDQ) |
| Study Confounding | Low | Adequate adjustment (age, work status, LBP‐related benefits status, LBP‐related compensation status, reporting at least 1 comorbidity, reporting at least 1 co‐treatment, duration of LBP, clinic type, and healthcare sector) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Butler 2007 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 51%; non‐participants not adequately described |
| Study Attrition | Moderate | 87% follow‐up at 1 month, 62% at 6 months, 42% at 1 year; no information on attempts to collect or possible reasons |
| Prognostic Factor Measurement | Moderate | Continuous measure of PF with good face validity (5‐point expectations of recovery) dichotomised for analyses without rationale provided |
| Outcome Measurement | Low | Unclear validity and reliability measurement of RTW outcome (unstable employment pattern) |
| Study Confounding | Low | Adequate adjustment (age, work status, LBP‐related benefits status, LBP‐related compensation) status, reporting at least 1 comorbidity, reporting at least 1 co‐treatment, duration of LBP, clinic type, and healthcare sector) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Carriere 2015 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participants were consecutive referrals to a clinic |
| Study Attrition | Moderate | 78% follow‐up; no description of reasons |
| Prognostic Factor Measurement | Moderate | Data driven cut‐point used to categorise a continuous measure of PF with good face validity (likelihood of RTW; 0 ‐ 100) |
| Outcome Measurement | Moderate | Unclear measure of RTW status |
| Study Confounding | Low | Adeqaute adjustment (age, sex, work disability, pain severity, number of pain sites) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Casey 2008 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline characteristics adequately described |
| Study Attrition | Moderate | 87% follow‐up; significant difference in those lost to follow‐up on pain constancy |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (Pain Behaviour and Perception Inventory pain permanence subscale) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (mean VAS, PDI) |
| Study Confounding | Moderate | Minimal adjustment (previous pain, baseline pain, baseline disability, cumulative trauma, depressive symptoms, pain permanence beliefs, pain constancy beliefs, chronic pain intensity (3 months)) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Demmelmaier 2010 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate 39%; non‐participants not adequately described |
| Study Attrition | High | 37% follow‐up; no information provided on reasons or differences in characteristics |
| Prognostic Factor Measurement | High | Unclear measurement properties of PF; group median used to substitute missing data |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (GCPS, sick leave yes/no) |
| Study Confounding | Moderate | Minimal adjustment (pain intensity baseline, disability, pain catastrophising, fear of movement, functional self‐efficacy) |
| Statistical Analysis and Reporting | Moderate | Appropriate analysis for research question and study design; possible selective reporting of results |
| Study ID: Dionne 1997 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 72%; non‐participants not adequately described |
| Study Attrition | Low | 92% follow‐up |
| Prognostic Factor Measurement | Moderate | Unclear validity and measurement properties (5‐point expectation of continued pain with no time period included) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (RMDQ) |
| Study Confounding | High | Univariate only available for our review question |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Downie 2016 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 67%; non‐participants not adequately described |
| Study Attrition | Low | 96% follow‐up at 3 months |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (risk of persistence; 0 ‐ 10) |
| Outcome Measurement | Moderate | Persistent high pain (≥ 5 on NRS) cluster and rapid recovery (< 1 on NRS) data available (clusters represent extremes) |
| Study Confounding | Low | Adequate adjustment (age, sex, taking paracetamol, compensable, pain intensity, duration, pain beyond knee, previous episodes, days of reduced activity, poor sleep quality, quality of life physical, quality of life mental, disability) |
| Statistical Analysis and Reporting | Low | While we were only able to use a subset of the data, authors used an appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Du Bois 2008 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline sample adequately described |
| Study Attrition | Low | 100% follow‐up; work status recorded by the sickness fund |
| Prognostic Factor Measurement | Moderate | Continuous measure of PF with good face validity (10‐point Likert scale for probability of RTW within 6 months); dichotomised for analyses without rationale |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (RTW at 3 months) |
| Study Confounding | Moderate | Minimal adjustment (pain below knee, pain interference) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Enthoven 2006 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 58%; inclusion criteria and non‐participants adequately described |
| Study Attrition | Low | 93% follow‐up at 1 year, 83% at 5 years |
| Prognostic Factor Measurement | Moderate | Continuous measure of PF with good face validity (5‐point expectations of restoration) dichotomised for analyses without rationale |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (ODI, sick leave duration) |
| Study Confounding | Low | Adequate adjustment (age, sex, duration of current episode, similar problems during previous 5 years, exercise frequency before, exercise level before, dissatisfied with work, dissatisfied with workplace, more than one localisation, pain frequency, ODI score, well‐being, current sick leave) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Enthoven 2016 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 53%; non‐participants not adequately described |
| Study Attrition | Low | 93% follow‐up at 3 months; reasons for loss provided |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (5‐point expectations of recovery) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (NRS, RMDQ) |
| Study Confounding | High | Univariate only available for meta‐analyses |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Foster 2008 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 51.4%; non‐participants not adequately described |
| Study Attrition | High | 65% follow‐up at 6 months; no information provided on reasons for loss |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (IPQ‐R items) (Moss‐Morris 2002) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (pain duration); clinical rationale used to dichotomise RMDQ |
| Study Confounding | Low | Adequate adjustment (sex, education, catastrophising, fear avoidance, social class, pain intensity, RMDQ, pain duration, leg pain, distal pain, anxiety, depression, 4 more domains of CSQ, 6 domains of IPQR, passive coping) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: George 2010 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 81% |
| Study Attrition | Low | 67% follow‐up at 6 months; no differences found between dropouts and those with follow‐up data |
| Prognostic Factor Measurement | Moderate | Valid and reliable measure of PF (items from NASS lumbar spine outcome assessment instrument); dichotomised for analyses without rationale |
| Outcome Measurement | Low | Valid and reliable measure of outcome (von Korff) |
| Study Confounding | High | Univariate only |
| Statistical Analysis and Reporting | Low | Analysis not sufficient for our review question; combines 4‐week and 6‐month outcome data |
| Study ID: Gervais 1991 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 96% |
| Study Attrition | Low | 98% follow‐up |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (self‐efficacy and results expectancies inventory) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (RTW time, recurrence, and at 6 months) |
| Study Confounding | Moderate | Minimal adjustment (diagnosis, lowest pain intensity, length of inactivity before treatment, negative life changes) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Glattacker 2013 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 59%; non‐participants not adequately described |
| Study Attrition | Moderate | 74% follow‐up; no description of reasons; dropouts had higher baseline disability may bias results |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (IPQ‐R items) (Moss‐Morris 2002) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS, ODI, SF‐36 scales) |
| Study Confounding | Low | Adequate adjustment (baseline health, baseline mental health, age, sex, education, illness duration, psychological outcome expectation, process expectation, rehabilitation‐specific concerns, identify, consequences, personal control, treatment control, coherence, emotional representation, cause (overwork)) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Goldstein 2002 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 46.4%; reasons for not participating adequately described |
| Study Attrition | Low | 96% follow‐up |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (NRS treatment confidence, 0 ‐ 10) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (NRS, RMDQ) |
| Study Confounding | Moderate | Minimal adjustment (baseline disability, age, gender, race, treatment group, duration of LBP episode) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Gross 2010 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participants drawn from workers' compensation database; non‐participants not described |
| Study Attrition | Low | Claim‐based outcome measure; available for all participants included |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (Work‐related Recovery Expectations Questionnaire) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (time to claim closure or suspension of time‐loss benefits, recurrence) |
| Study Confounding | Low | Adequate adjustment (age, sex, job attachment status, duration of injury, number of previous claims, urban/rural) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Grotle 2006 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate unclear; supplemental recruiting from general population |
| Study Attrition | Moderate | 91% and 94% follow‐up at 1 year for each group; no reasons provided for loss to follow‐up |
| Prognostic Factor Measurement | Moderate | Valid and reliable measure of PF (Acute Low Back Pain Screening Questionnaire item), data driven cut‐point used for analyses |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (NRS, days of participation restriction) |
| Study Confounding | Moderate | Minimal adjustment (age, sex) |
| Statistical Analysis and Reporting | Low | Analysis not sufficient for our study purposes only, expectations included as an item of a larger measure |
| Study ID: Haas 2014 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate 42%; recruitment from general population |
| Study Attrition | Low | 98% follow‐up |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (Interstudy’s Low Back Pain TyPE Specification) |
| Outcome Measurement | Low | Valid and reliable measure of outcome (von Korff) |
| Study Confounding | Moderate | Minimal adjustment for relationship between baseline expectations and outcome (expectations at 6 and 12 weeks, doctor‐participant encounter at 6 and 12 weeks, LBP at 6 and 12 weeks) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design with conceptual model |
| Study ID: Hagen 2005 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline characteristics adequately described |
| Study Attrition | Low | 99% follow‐up at 1 year |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability of PF measurement and unclear measurement properties (Do you believe back pain will disappear?) |
| Outcome Measurement | Low | RTW determined from administrative claims database |
| Study Confounding | Low | Adequate adjustment (gender, age, education, group (intervention vs control), large reduced ability to regularly work, constant back strain > 50% of the working time, gastrointestinal problems, high chance externality (health locus of control), believe work will aggravate condition, pain when performing daily activities, state anxiety, other illnesses + 4 interaction terms) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Haldorsen 1998 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 54%; non‐participants not adequately described; baseline sample adequately described |
| Study Attrition | Low | 100% follow‐up at 1 year |
| Prognostic Factor Measurement | High | Unclear validity, reliability of PF and unclear measurement properties of PF (If you continue working, what effect will that have on your complaints?) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (sick‐listed) |
| Study Confounding | High | Univariate only |
| Statistical Analysis and Reporting | Moderate | Appropriate analysis for research question and study design; possible selective reporting of results |
| Study ID: Harkapaa 1996 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate unclear; no description of non‐participants, limited description of participants |
| Study Attrition | Moderate | 74% follow‐up at 1 year; no information provided on reasons or differences in characteristics |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (Optimism Index) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (work status), valid rationale used to categorise Functional Capacity Index |
| Study Confounding | Low | Adequate adjustment (age, sex, work status at baseline, baseline disability, others' locus of control) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Hazard 1996 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 24%; non‐participants were described and compared with small mean differences |
| Study Attrition | Low | 98% follow‐up at 3 months |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (Vermont Disability Prediction Questionnaire item) |
| Outcome Measurement | Low | Self‐report measure of RTW with unclear measurement properties |
| Study Confounding | Moderate | Insufficient data on which Vermont Disability Prediction Questionnaire domains included in final multivariate model; age and sex not included |
| Statistical Analysis and Reporting | Moderate | Analysis not sufficient for our study purposes only, expectations included as an item of a larger measure; no conceptual framework; data driven based on P values of univariate associations |
| Study ID: Henschke 2008 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 92.1% |
| Study Attrition | Low | 99% follow‐up |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (NRS perceived risk of persistence, 0 ‐ 10) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (SF‐36, return to previous work status) |
| Study Confounding | Low | Adequate adjustment (age, sex, pain intensity, interference with function, pain control, tension/anxiety, feelings of depression, compensable LBP, currently taking medications for LBP, days of reduced activity due to LBP, leg pain, no of pain sites, duration of episodes) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Heymans 2006 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline sample adequately described |
| Study Attrition | Low | 100% follow‐up (90% with complete baseline data) |
| Prognostic Factor Measurement | Low | Good face validity, unclear reliability of PF (time to RTW in categories and 5‐point scale for certainty of RTW) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (time to full RTW) |
| Study Confounding | Low | Adequate adjustment (job satisfaction, social support, pain radiation in 1 or both legs, pain intensity) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; comprehensive method for backwards selection of variables |
| Study ID: Hildebrandt 1997 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate and recruitment approach unclear |
| Study Attrition | Moderate | 91% follow‐up; some non‐participants lost due to refusal to participate, and not adequately described |
| Prognostic Factor Measurement | Moderate | Mix of treatment and general expectations; unclear measurement properties of PF (RTW after treatment) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS, sick‐listed Y/N) |
| Study Confounding | High | Univariate only |
| Statistical Analysis and Reporting | Moderate | Analysis not sufficient for our study purposes only, outcome measured at 6 and 12 months but not analysed; Only mean and standard deviation of expectations measure presented for success and failure in outcome |
| Study ID: Jellema 2002 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate unclear (workers volunteered) |
| Study Attrition | Moderate | 83% follow‐up; reasons for loss to follow‐up provided, but no information provided on differences in characteristics |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (NRS treatment confidence, 0 ‐ 10) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (NRS, Quebec Back Pain Disability Scale, time lost from work) |
| Study Confounding | High | Univariate data only measures change in pain intensity with no other baseline variables taken into account; no data available for meta‐analyses |
| Statistical Analysis and Reporting | High | Analysis not sufficient for our study purposes only, outcome measured weekly and mean benefit over 6 months used for analysis |
| Study ID: Jensen 2000 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline characteristics adequately described |
| Study Attrition | Moderate | 69% follow‐up in sample 1, 100% in sample 2; no information provided on reasons or differences in characteristics |
| Prognostic Factor Measurement | Moderate | Unclear measurement properties of PF; unclear validity, reliability of PF (Belief that there is a treatment that could relieve condition; Belief in ability for learning to cope with the pain) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (SF‐36, days sick leave, disability pension Y/N) |
| Study Confounding | Moderate | Minimal adjustment (attending physician's judgement, attending physiotherapist's judgement of need and potential; insurance officer judgement of need and potential; screening physician judgement of need and of potential) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Jensen 2013 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline characteristics adequately described |
| Study Attrition | Low | 100% follow‐up |
| Prognostic Factor Measurement | Moderate | Good face validity, unclear reliability of PF (time to RTW categories) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (successful RTW for at least 4 weeks) |
| Study Confounding | Moderate | Minimal adjustment (pain side flexion, blaming work for pain, drinking alcohol, radiculopathy, BMI, age, sex) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; method for backwards selection of variables |
| Study ID: Karjalainen 2003 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline characteristics adequately described |
| Study Attrition | Low | 95% follow‐up |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (NRS expectations of treatment effectiveness, 0 ‐ 10) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (NRS, ODI, sick leave because of back pain) |
| Study Confounding | Low | Adequate adjustment (gender, age, BMI, blue‐collar worker, duration of sick leave at baseline, radicular symptoms below the knee, intensity of pain at baseline, ODI, satisfaction with work, self‐rated health status for age) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Kongsted 2014 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 98% |
| Study Attrition | Moderate | Unclear attrition at 6 months and 1 year, 76% ‐ 83% follow‐up at 3 months; no information provided on reasons or differences in characteristics |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (NRS) |
| Outcome Measurement | Low | Valid and reliable measure of outcomes (NRS and RMDQ) |
| Study Confounding | Low | Adequate adjustment (Model 1: age, gender, education, any sick leave previous month, LBP at baseline, leg pain at baseline, activity limitation at baseline, duration of LBP, number previous episodes of LBP, depression) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Leboeuf‐Yde 2004 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; selection criteria and baseline characteristics adequately described |
| Study Attrition | Moderate | 68% follow‐up at 3 months, 59% at 1 year; gender differences at each follow‐up from baseline, no reasons for loss reported |
| Prognostic Factor Measurement | Moderate | Validity, reliability and measurement properties of PF unclear (helpfulness of treatment, sick leave in 6 weeks, yes/no; 4‐point improvement of pain in 6 weeks) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (pain 0 ‐ 10, ODI), clinical rationale used to dichotomise for analyses |
| Study Confounding | Moderate | Minimal adjustment at 3 months (sex, pain severity, episode duration, neck pain) and 12 months (disability, activity limitation) |
| Statistical Analysis and Reporting | Moderate | Analysis not sufficient for our study purposes only, combines 4‐week, 3‐month and 12‐month outcome data; no conceptual framework; data driven based on P values of univariate associations |
| Study ID: Lindell 2010 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 85% |
| Study Attrition | Low | 99% follow‐up at 6 months, 98% at 1 year |
| Prognostic Factor Measurement | Moderate | Continuous measure of PF with good face validity (5‐point expectations of RTW) dichotomised for analyses without rationale provided |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (successful RTW for at least 1 month) |
| Study Confounding | Low | Adequate adjustment (age, education, type of back pain, back pain domination, catastrophising, total prior sick‐listing) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; method for backwards selection of variables |
| Study ID: Macedo 2014 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 68.5%; non‐participants not adequately described |
| Study Attrition | Low | 87% ‐ 93% follow‐up; no differences found between dropouts and those with follow‐up data |
| Prognostic Factor Measurement | Moderate | Valid and reliable measure of expectations (PSEQ) dichotomised for analyses without rationale provided |
| Outcome Measurement | Low | Valid and reliable measure of outcomes (NRS and Patient‐Specific Function Scale) |
| Study Confounding | High | Univariate only for PF association data (TEM analysis) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Magnussen 2007 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; adequate description of non‐participants but no reasons for not participating/exclusion |
| Study Attrition | Moderate | 91% follow‐up; reasons provided for not completing intervention but not questionnaire, no information on differences in characteristics |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability, and measurement of PF (ever RTW, "don't know" grouped with "no" for analyses) |
| Outcome Measurement | Moderate | Unclear validity and reliability measurement of RTW outcome (self‐report of being in a RTW process with unclear measurement properties; additional outcome ‐ RMDQ) |
| Study Confounding | High | Univariate only |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Michaelson 2004 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 98% |
| Study Attrition | Low | 75% follow‐up at 1 year; authors indicate no differences between dropouts and those with follow‐up data |
| Prognostic Factor Measurement | Low | Valid and reliable measure of expectations (Optimism Index) |
| Outcome Measurement | Low | Clinical rationale provided for categorisation of continuous outcome (VAS) |
| Study Confounding | Moderate | Minimal adjustment (age, sex, optimism index, MPI pain severity, pain intensity on average); no data available for meta‐analyses |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Morlock 2002 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear; inclusion criteria adequately described, baseline sample not adequately described |
| Study Attrition | High | Unclear attrition; no information provided on reasons or differences in characteristics |
| Prognostic Factor Measurement | Low | Continuous PF measure with good face validity (combining 5 5‐point scales of treatment expectation) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (NASS) |
| Study Confounding | Low | Adequate adjustment (age, baseline NASS score, workers compensation status, gender, race, acuity, symptom location, Charlson Comorbidity Index) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Myers 2007 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 66%; selection criteria, reasons for not participating, and baseline characteristics adequately described |
| Study Attrition | Low | 99% at follow‐up |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (NRS likelihood of recovery, 0 ‐ 10) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (RMDQ) |
| Study Confounding | Low | Adequate adjustment (age, race, income, baseline disability, depression, history of sciatica, 2nd time seeing doctor for LBP, baseline pain) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; comprehensive method for backwards selection of variables |
| Study ID: Niemisto 2004 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 97% |
| Study Attrition | Low | 96% follow‐up |
| Prognostic Factor Measurement | Moderate | Independent measurement properties of PF unknown (item of Workability Index) dichotomised for analyses without rationale provided |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS, ODI, Work‐ability Index, number of days on sick leave) |
| Study Confounding | Low | Adequate adjustment (university education; VAS score; sick leave days during previous year; life control; SLUMP test) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Opsahl 2016 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 100% |
| Study Attrition | Low | 99% follow‐up |
| Prognostic Factor Measurement | Moderate | Low and moderate expectancies grouped for analyses due to data constraints (4‐point rating of extent of RTW) |
| Outcome Measurement | Moderate | Unclear measure of RTW status |
| Study Confounding | Low | Adequate adjustment (Model 1: age, education, fear avoidance, smoking status, intervention groups, subjective health complaint inventory total, ODI, Hopkins Symptom Checklist (HSCL‐25) (emotional distress), co‐worker social support) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Opsommer 2017 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 89.5% |
| Study Attrition | Moderate | 79.5% follow‐up; coping strategies and fear avoidance higher (worse) in dropouts may bias results |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (Orebro Musculoskeletal Pain Questionnaire items) |
| Outcome Measurement | Moderate | Unclear measure of RTW status |
| Study Confounding | High | Univariate only |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Petersen 2007 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participants were consecutive referrals to a clinic; sample adequately described |
| Study Attrition | Low | 93% follow‐up at 1y, 83% at 5 years |
| Prognostic Factor Measurement | Moderate | Continuous measure of PF with good face validity (11‐point box scale, certainty of RTW) dichotomised for analyses without rationale provided |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (sick‐listed), valid rationale used to categorise Low Back Rating Scale for analyses |
| Study Confounding | Moderate | Minimal adjustment (baseline disability, on sick leave, low job satisfaction, pain below the knee) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; comprehensive method for backwards selection of variables |
| Study ID: Rasmussen‐Barr 2012 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 93% |
| Study Attrition | Moderate | 86% follow‐up at 1 year; reasons provided, lost to follow‐up had lower physical health, may bias results |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability of PF and unclear measurement properties of PF |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS, ODI), valid rationale used to dichotomise scores for analyses |
| Study Confounding | High | Univariate only |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Reeser 2001 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear (recruitment at appointment booking); selection criteria and baseline characteristics adequately described |
| Study Attrition | High | 35% completed questionnaires at all follow‐up times at were included; respondents were older, may bias results; no reasons for loss provided |
| Prognostic Factor Measurement | Low | Continuous PF measure with good face validity (combining 5 5‐point scales of treatment expectation) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (MODEMS Physical Health and Pain scale, MODEMS Physical Health and Disability scale) |
| Study Confounding | High | No statistical models were used to assess the association between the expectations and the outcomes of interest |
| Statistical Analysis and Reporting | Moderate | No statistical models were used to assess the association between the expectations and the outcomes of interest; possible selective and unclear reporting of results |
| Study ID: Reiso 2003 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate unclear (referred from primary care); selection criteria and baseline sample adequately described |
| Study Attrition | Low | Primary outcome return to work for 60+ days supplied by national register; no loss to follow‐up |
| Prognostic Factor Measurement | Moderate | Measure of PF with good face validity (RTW, part‐time RTW, still on sick leave) dichotomised for analyses without rationale provided |
| Outcome Measurement | Low | Valid and reliable measure of RTW (working for at least 60 consecutive days) from national register |
| Study Confounding | Low | Adequate adjustment (age, gender, diagnosis, pain intensity, workability) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Reme 2009 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate 65%; inclusion criteria, reasons for not participating, and baseline sample adequately described |
| Study Attrition | Low | 99% follow‐up at 3 months, 97% at 1 year |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability of PF measurement and unclear measurement properties of PF (Expectation to return to work within the next few weeks (yes/no)) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (sick leave and non‐RTW from insurance claims, self‐reported sick‐listing) |
| Study Confounding | Low | Adequate adjustment (group, gender, age, education, workload, sleep problems, reduced ability to walk, physiotherapy, back pain intensity, pain during activity, pain during rest) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Rundell 2017 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Unclear participation rate; baseline sample and selection criteria adequately described; unclear reasons for not participating |
| Study Attrition | Moderate | 79% follow‐up at both 6 months and 1 year; no information provided on reasons for differences in characteristics |
| Prognostic Factor Measurement | Low | Continuous measure of PF at 6‐ and 12‐month follow‐up with good face validity (confidence in recovery; 0 ‐ 10); categorised for 3‐month follow‐up |
| Outcome Measurement | Low | Valid and reliable measure of outcomes (NRS and RMDQ); clinical rationale provided for categorisation of continuous |
| Study Confounding | Moderate | Minimal adjustment (age, sex, education, race, employment status, marital status, study site) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Sandstrom 1986 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Reported as consecutive referrals, but baseline sample not adequately described |
| Study Attrition | Low | 100% follow‐up |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability of PF and unclear measurement properties of PF ("Afraid to start working again, because I don't think I will be able to manage") |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (sick‐listed Yes/No) |
| Study Confounding | High | Unclear variables included in stepwise models |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Schultz 2004 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate 43%; non‐participants not adequately described |
| Study Attrition | Low | 83% ‐ 92% follow‐up; no reasons for loss provided, but dropouts not significantly different from responders |
| Prognostic Factor Measurement | Low | Valid and reliable measure of PF (8 questions on RTW expectations) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (days lost due to low back disability in past 18 months, RTW status at 18 months) |
| Study Confounding | Moderate | Minimal adjustment (LBP subgroup, SF‐36 Health Transition, and Karasek’s coworker support scale) |
| Statistical Analysis and Reporting | Moderate | No conceptual framework; data driven based on P values of univariate associations |
| Study ID: Shaw 2009 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | High | Participation rate unclear (volunteers); no description of eligible non‐participants; full baseline sample not described |
| Study Attrition | Moderate | 91% follow‐up at 3 months; non‐responders were different on age, gender, and education |
| Prognostic Factor Measurement | Moderate | Unclear validity and reliability of PF (full RTW at 4 weeks categorized, 'unlikely' grouped with 'not sure' for analyses) |
| Outcome Measurement | Moderate | Unclear validity and reliability measurement of RTW outcome (self‐report RTW with unclear measurement properties); valid and reliable measurement of pain, function (NRS, RMDQ) |
| Study Confounding | Low | Adequate adjustment (age, gender, education, income, race, body mass index, smoking status, cause of injury, pain intensity rating, changes in pain since onset, missed a day of work already, job tenure, negative supervisor response, physical job demands, prior back surgery, past work absence due to LBP, employer allows modified duty, job enjoyment, worries about re‐injury, frequency of moderate exercise, general health rating, felt downhearted and blue, felt under stress) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
| Study ID: Sherman 2009 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 78%; non‐participants not adequately described |
| Study Attrition | Low | 91% follow‐up 6 months and 1 year; reasons for loss provided and not likely to bias results |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability of PF measurement and unclear measurement properties of 1 of the 2 PFs (Likelihood of self‐managing future back pain) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (RMDQ) |
| Study Confounding | Low | Adequate adjustment (baseline RMDQ score, baseline bothersomeness score, any disability, SF‐36 mental health score, age, gender, education level, employment, medication use, duration of chronic LBP, pain travels below knee, days of LBP in last 3 months, intense LBP treatment, treatment group) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results; conceptual framework for inclusion of covariates |
| Study ID: Steenstra 2005 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Workers on sick leave required to submit baseline form to their employer (full participation) |
| Study Attrition | Low | 100% follow‐up |
| Prognostic Factor Measurement | Moderate | Unclear validity, reliability of PF measurement (sick leave > 10 or not) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (RTW, lasting RTW, total days sick leave) |
| Study Confounding | Moderate | Minimal adjustment (treatment by GP or specialist, seeking OP care, the interaction between the self‐reported expected duration of sick leave and seeking OP care, complaints due to job stress, diminished mobility, and the interactions between expected duration of more than 10 days and seeking OP care and between seeking OP care and diminished mobility) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results; conceptual framework for inclusion of covariates |
| Study ID: Tran 2015 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 52%; non‐participants not adequately described |
| Study Attrition | Low | 96% follow‐up |
| Prognostic Factor Measurement | Moderate | Data‐driven cut‐point used to categorise a continuous measure of PF with good face validity (expectation of helpfulness of treatment; 0 ‐ 10) |
| Outcome Measurement | Low | Valid and reliable measure of outcomes (NRS and RMDQ) |
| Study Confounding | Moderate | Minimal adjustment (age, sex, education, treatment arm, baseline SF‐36 Physical Component Score, baseline RMDQ score); univariate data only available for meta‐analyses |
| Statistical Analysis and Reporting | Moderate | Only mean and SD presented for change in each outcome by high and low expectations are presented; results of multivariate linear regression not presented due to non‐significance of PFs |
| Study ID: Truchon 2012 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 77%; non‐participants not adequately described |
| Study Attrition | Low | 99% follow‐up |
| Prognostic Factor Measurement | High | Unclear validity, reliability of PF measurement and unclear measurement properties of PF (Return to work expectations (time)) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (number of days of absence) |
| Study Confounding | Low | Adequate adjustment (work‐related fear avoidance beliefs, annual family income, level of education, work schedule (irregular), work concerns) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results; conceptual framework for inclusion of covariates |
| Study ID: Turner 2008 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participation rate 51%; participants and non‐participants adequately described; non‐participants older and higher disability |
| Study Attrition | Low | 100% follow‐up |
| Prognostic Factor Measurement | Moderate | Continuous measure of PF with good face validity (NRS likelihood of recovery, 0 ‐ 10) categorised for analyses without rationale |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (wage replacement compensation for disability at 12 months) |
| Study Confounding | Low | Adequate adjustment (mental health, catastrophising, blame, relations with co‐workers, work fear‐avoidance, age, gender, race, education, pain intensity, RMDQ, "and other psychosocial variables") |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results; conceptual framework for inclusion of covariates |
| Study ID: Underwood 2007 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Low | Participation rate unclear; baseline sample and inclusion criteria adequately described |
| Study Attrition | Moderate | 77% follow‐up at 3 months, 75% follow‐up at 1 year; no information provided on reasons or differences in characteristics |
| Prognostic Factor Measurement | Moderate | Unclear validity and reliability of PF measurement (3‐pt Likert on treatment helpfulness) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (modified von Korff, RMDQ) |
| Study Confounding | Low | Adequate adjustment (manipulation and exercise, manipulation, exercise, additional education, working, age, male, pain and disability, quality of life, beliefs, episode length) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results; conceptual framework for inclusion of covariates |
| Study ID: Van Hooff 2014 | ||
| Domain | Risk of bias level | Support for judgement |
| Low | Participation rate 84% | |
| Low | 87% follow‐up; authors indicate no differences between dropouts and those with follow‐up data | |
| Low | Valid and reliable measure of PF (PSEQ) | |
| Low | Valid and reliable measure of outcome (ODI); clinical rationale provided for categorisation of continuous outcome | |
| Moderate | Minimal adjustment (function and employment); univariate only available for meta‐analyses | |
| Moderate | Only mean and standard deviation of expectations measure presented for success and failure in outcome | |
| Study ID: Van Wijk 2008 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | Participants from two trials (79% and 98% participation); selection criteria may lead to bias selected chronic group with no treatment response; response to facet joint block required |
| Study Attrition | Low | 100% follow‐up at 3 months, 82% at 1 year; reasons provided, no information on differences in characteristics |
| Prognostic Factor Measurement | High | Unclear which item of PCL is used for analyses, unclear description of PF |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS, Physical Activity Scale) |
| Study Confounding | Low | Adequate adjustment (baseline pain, 5 psychosocial domains: psychologically negative, adaptive manager, inflexible qualities, supporting partner, strong ego); no data available for meta‐analyses (expectations reported as part of a factor) |
| Statistical Analysis and Reporting | Low | Analysis not sufficient for our study purposes only, expectations used to define psychological profile clusters for analyses |
| Study ID: Yelland 2006 | ||
| Domain | Risk of bias level | Support for judgement |
| Study Participation | Moderate | 80% participation among eligible; inclusion criteria of high disability and failure to respond to conservative treatment may lead to bias |
| Study Attrition | Low | 99% follow‐up at 6 months, 96% at 1 year |
| Prognostic Factor Measurement | Low | Continuous measure of PF with good face validity (% improvement expected with treatment; 0 ‐ 100) |
| Outcome Measurement | Low | Valid and reliable measurement of outcome (VAS) |
| Study Confounding | Moderate | Minimal adjustment (age, gender) |
| Statistical Analysis and Reporting | Low | Appropriate analysis for research question and study design; no apparent selective reporting of results |
PF = prognostic factor; RMDQ = Roland Morris Disability Questionnaire; TEM = treatment effect modifier; RTW = return to work; VAS = pain visual analog scal; LBP = low back pain; PDI = Pain Disability Index; GCPS = Graded CHronic Pain Scale; NRS = pain numeric rating scale; ODI = Oswestry Disability Index; IPQ‐R = Illness Perception Questionnaire (revised); CSQ = Coping Strategies Questionnaire; NASS = North American Spine Society Outcome Assessment scale; SF‐36 = 36‐item Short Forum Survey; BMI = body mass index; PQEQ = Pain Self‐efficacy Questionnaire.