Table 2

Review and intervention characteristics of included reviews (n=9)

First author (year), country	Type of studies included (N)	Diagnosis 1. Participants (range) 2. Age 3. Per cent F gender 4. Per cent employed at baseline	Type of intervention according to author(s) 1. Aim 2. Content 3. Disciplines	Type of outcome	Results
Medium quality reviews (AMSTAR)
Clayton (2011), England18	QL (20) UCS (5) CCS (4) CS (2) NR (17)	Long-term sick or disabled people* NR NR NR NR	Governmental RTW initiatives Help long-term sick or disabled people into work (A) Individual case management and job search assistance, (B) financial incentives, (C) medical rehabilitation and/or advice on health condition management to improve fitness at work NR	RTW, defined as getting back to work or getting employment	(A) 2 CCS and 1 UCS reported that the intervention significantly enhanced the employment rate (p<0.05). 2 CCS and 1 CS found no significant effect. 3 QL studies reported beneficial effects, 3 QL studies reported no effect and 6 studies (5 QL, 1 CS) were unclear. (B) No significant effect was found (1 UCS), evidence unclear (3 QL). (C) All 4 QL reported beneficial effects. No effect sizes were reported
Gensby (2014), Denmark19	PPD (10) NRCT (2)	(Non-) occupational illnesses or injuries (MSD 10×, mental disorders 2×) 55 320 (58–28 518) NR NR NR	Workplace disability management programmes RTW RTW programme provided by the employer, including early contact, active employee participation, disability case information and monitoring system, case management, modified work, workplace assessment, physical rehabilitation services, workplace accommodation, RTW policies Multidisciplinary	RTW, defined as time to first RTW, duration of sickness absence followed by RTW or reduction in lost days from work	All studies reported the included interventions to be effective in various outcomes related to work participation. However, no effect sizes were reported and it was not reported if there were significant differences between the intervention and control groups
Van Oostrom (2009), The Netherlands20	RCT (5)	MSD (5×), mental health problems (1×) 749 (120–205) NR NR NR	Workplace interventions Prevent work disability by reducing barriers to RTW Changes to the workplace or equipment, changes in work design and organisation, changes in working conditions or work environment, case management with worker and employer Multidisciplinary	RTW, defined as time until first RTW after a period of sickness absence	A workplace intervention was more effective than CAU at the 12-month follow-up for time until first RTW (HR 1.55, 95% CI 1.32 to 2.16)
Franche (2005), Canada21	RCT (2) PC (1) PPDN (1) CS (1)	MSD, carpal tunnel syndrome, work-related injury and illness* 58 262 (104–55 275) NR NR NR	Workplace-based RTW interventions Improving RTW outcomes EC, RTWC, WEV, WA, HCP, physiotherapist, SP Multidisciplinary	RTW, operationalised as work disability duration and RTW rate	All studies reported effectiveness for the intervention, with 1 RCT reporting a higher RTW rate (OR 2.2, 95% CI 1.04 to 4.80) and faster RTW (OR 1.9, 95% CI 1.18 to 3.10). 1 RCT found no difference in intervention and control in time to first RTW and total work disability duration. No effect sizes were reported. 1 PC reported that the RTW rate was higher when workers had a modified job to return to (RR 1.93, 95% CI 1.54 to 2.42). 1 PPDN and 1 CS reported positive effects but no effect sizes
Nevala (2014), Finland22	RCT (1) CCT (1) PC (1)	Rheumatic diseases, TBI, MSD 1060 (6–502) 16–68 15–100 NR	Work accommodations Promoting and maintaining employment Work accommodations, consisting of: redesign of work schedules, work organisation, the environment, assistive technology, assistance of others, special transportation and legislation NR	Employment, defined as getting employment, WR and RTW	1 RCT and 1 PC reported moderate evidence that specific types of work accommodations (vocational counselling and guidance, education and self-advocacy, help of others, changes of work schedules, work organisation, and special transportation) maintain employment (OR 0.58, 95% CI 0.34 to 0.99) and increase the employment rate (OR 5.61, 95% CI 2.23 to 14.09). 1 CCT reported no significant effectiveness of workplace accommodation (OR 2.0, 95% CI 0.77 to 5.23)
Low quality reviews (AMSTAR)
Bambra (2005), England23	MM (10) QL (4) Survey (2)	Disability or chronic illness* NR NR NR 0	Governmental welfare-to-work programmes Help individuals with a disability or chronic illness to move into work (A) Education, training and work placement; (B) vocational advice and support services; (C) strategies of in-work benefits; (D) employer incentive schemes; (E) physical accessibility initiatives NR	Gaining competitive employment, defined as increasing employment changes	(A) All 4 MM studies reported a positive impact on employment with a 15–50% employment rate. (B) 1 MM controlled study did not find a significant difference in employment. 1 survey, 1 MM and 1 QL, reported an increase in employment from 18% to 26% (survey) and 75% (MM). (C) 1 MM study found no significant difference after intervention. 1 survey and 2 QL studies reported a positive influence of the intervention. (D) 2 QL studies reported a positive influence on employment. (E) 3 MM and 1 QL study found a positive influence on employment. No effect sizes were reported
Désiron (2011), Belgium24	RCT (3) PC (1)	CLBP, major depressive disorder, whiplash injury, TBI 899 (NR) NR NR 100	Occupational therapy interventions RTW (A) FRP vs active individual therapy; (B) CAU vs CAU+occupational therapy; (C) progressive goal attainment vs FRP; (D) cognitive-didactic programme vs skills development Multidisciplinary	RTW, defined as work-related outcomes (ie, RTW, sick leave, employment status)	(A) FRP was more effective than active individual therapy in reducing the number of sick leave days (1 RCT). (B) Occupational therapy vs CAU increases RTW (1 RCT). (C) Progressive goal attainment+FRP can lead to significant increases in the RTW (75% vs 50%; 1 PC). (D) No differences in RTW between a cognitive-didactic programme vs FRP (1 RCT). No effect sizes were reported
Varekamp (2006), The Netherlands25	PPD (2) PPDN (1) PTN (1) PT (1)	Kidney failure (2×), MS, rheumatic diseases (2×) 851 (30–242) NR NR 26–100	Vocational rehabilitation interventions including empowerment perspective WR by means of solving work-related problems (A) education, assessment and individual counselling; (B) education, peer interaction and individual exercises Multidisciplinary	WR, defined as employment status	(A) 1 PT reported that 47% of blue-collar workers retained job vs 24% (controls) (OR 2.8, p<0.05) and white-collar workers retained 47% job vs 48% (controls). 1 PPD study found no significant differences. 1 PTN study reported that 14/19 persons retained their job. 1 PPD reported that delay in job loss was significantly longer in the intervention group (p<0.05), temporary or permanent job loss 25/122, compared with 48/120 (controls) (OR 0.58, p<0.05). (B) 34/37 employed persons retained their job compared with 24/104 unemployed persons who gained a job (PPDN). No effect sizes were reported
Clayton (2012), England26	QL (10) MM (5) RCT (1) Survey (6) NR (8)	Long-term sick or disabled people* NR NR NR NR	Governmental RTW interventions Change employers’ behaviour towards disabled people (A) Anti-discrimination legislation; (B) workplace adjustments; (C) wage subsidies for employing disabled people; (D) engagement of employers in RTW planning. NR	RTW, defined as getting back to work, getting employment or WR	(A) 4 surveys and 4 MM reported no change in employment. (B) 3 of 4 positive reporting studies found that adjustments (flexible work schedule, modified work) significantly increased WR (mean increase 26% and 56%, p<0.05) (OR: 2.9, 95% CI 1.9 to 4.3) or reduced sickness absence, 6 studies (QL, MM) were unclear. (C) 1 RCT found a significantly higher RTW rate (85.2% vs 71.9%, p<0.0001). 4 (QL, NR) found no effect. (D) 1 study found a significant difference in sick leave between the intervention groups vs controls (p<0.05). 4 QL studies reported a positive effect, 2 studies were unclear. No effect sizes were reported

*Not specified which diagnoses.
Study design: CCS, controlled cohort study; CCT, controlled clinical trial; CS, cross-sectional; MM, mixed methods; NR, not reported; NRCT, non-randomised control trial; PC, prospective cohort study; PPD, pre-post design with control group; PPDN, pre-post design without control group; PT, post-test only with control group; PTN, post-test only without control group; QL, qualitative studies; RCT, randomised controlled trial; RTW, return to work; UCS, uncontrolled cohort study; WR, work retention.
Diagnoses: CLBP, chronic low back pain; MS, multiple sclerosis; MSD, musculoskeletal disorders; TBI, traumatic brain injury.
Intervention: CAU, care as usual; EC, early contact with worker by workplace; FRP, functional restoration programme; HPC, healthcare provider contact with workplace; RTWC, RTW coordination; SP, supernumerary replacement; WA, work accommodation offer; WEV, worksite ergonomic visit.