Walsh 1990.

Methods	RCT
Participants	Subjects: 90 male warehouse workers. Individuals currently being treated for back pain or back injury were excluded, although those with a prior history of back injury were not excluded. Mean age 29 years.
Interventions	Preventive intervention: 1) A lumbosacral orthosis at work plus back school: a 1‐hr training session on back pain prevention and body mechanics, 6 months (n=30). Control intervention: 2) Back school (n=30), 1‐hr training session. 3) No intervention (n=30).
Outcomes	Work injury incidence, productivity, use of health care services, days lost from work by back injury. Days lost from work significantly better in lumbar support group.
Notes	A total of 90 workers were randomly assigned. Follow‐up was obtained at 6 months from 82 workers. Only the data of these 82 workers is presented in the article. No data on compliance.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk
Allocation concealment?	High risk	C ‐ Inadequate
Blinding? All outcomes ‐ patients?	High risk
Blinding? All outcomes ‐ outcome assessor?	Low risk
Incomplete outcome data addressed? All outcomes ‐ drop‐outs?	Low risk
Incomplete outcome data addressed? All outcomes ‐ ITT analysis?	Unclear risk	Unclear from text
Similarity of baseline characteristics?	Low risk
Co‐interventions avoided or similar?	Unclear risk	Unclear from text
Compliance acceptable?	High risk	No data on compliance.
Timing outcome assessments similar?	Low risk