Reddell 1992.

Methods	RCT
Participants	Subjects: 642 fleet service clerks; 70 women, 572 men. Age range: 19‐67 years. 26% of 642 subjects had suffered a previous back injury and 56% a previous back pain. No data available regarding subjects with current LBP.
Interventions	Preventive intervention: 1) Weightlifting belt (n=145), belt use at work, 8 months. 2) Belt plus training class (n=127), belt use at work and 1 hour training class on spine anatomy and body mechanics. Control intervention: 3) Training class (n=122), 1 hour training class. 4) No intervention (n=248).
Outcomes	Lumbar injuries, lost work days case lumbar injury, restricted work days, case lumbar injury, compensation cost. No significant differences after 8 months.
Notes	Of the 896 clerks selected to participate in this study 642 were located and interviewed at the end of 8 months. Only data of these subjects is presented in the article. Compliance: 58% stopped using it before the end of 8 months. Complaints: heat production around the waist, the belt rides up and pinches ribs.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Unclear from text
Allocation concealment?	High risk	C ‐ Inadequate
Blinding? All outcomes ‐ patients?	High risk
Blinding? All outcomes ‐ outcome assessor?	High risk
Incomplete outcome data addressed? All outcomes ‐ drop‐outs?	Unclear risk	Unclear from text
Incomplete outcome data addressed? All outcomes ‐ ITT analysis?	High risk
Similarity of baseline characteristics?	Low risk
Co‐interventions avoided or similar?	High risk
Compliance acceptable?	High risk	Compliance: 58% stopped using it before the end of 8 months.
Timing outcome assessments similar?	Low risk