Werner 2005.

Study characteristics
Methods	Study design: quasi‐RCT Setting: a Midwestern auto assembly plant, USA
Participants	Details of sampling frame: Total n assessed for eligibility = 2636 Total n excluded pre‐randomisation = 2475 Total n randomised = 161 (161 wrists) randomised Intervention group 1 (splint + ergonomic education) n = 86 wrists  Intervention group 2 (ergonomic education) n = 75 wrists    Post‐intervention follow‐up: Total n available for follow‐up = 112 Total n analysed = 112 Intervention group 1 (splint + ergonomic education) n = 63 wrists  Intervention group 2 (ergonomic education) n = 49 wrists    Gender distribution: Intervention group 1 (splint + ergonomic education): 30 males, 33 females (completed the study) Intervention group 2 (ergonomic education): 25 males, 24 females (completed the study) Mean ± SD (range) age (for those who completed the study): Intervention group 1 (splint + ergonomic education): 44.74 ± 1.02 (25.6 to 59.0) years Intervention group 2 (ergonomic education): 43.77 ± 1.44 (25.5 to 59.2) years Mean ± SD duration of CTS symptoms: Not reported Inclusion criteria: Worker‐reported symptoms of numbness, tingling, burning, or pain in the wrist or the hand for more than a week or more than 3 times in the last 6 months Hand diagram was suggestive of CTS; that is, there were symptoms of numbness, tingling, burning, or pain in the median nerve distribution. Exclusion criteria: Upper‐extremity musculoskeletal disorders secondary to acute trauma on or off the job History of bilateral carpal tunnel release surgery Pregnancy CTS diagnostic criteria (case definition): Study examined the efficacy of splints among participants with symptoms consistent with CTS, but not necessarily having the diagnosis established. CTS severity:  Not reported
Interventions	Group 1 ‐ splint + ergonomic education: Customised wrist splints and ergonomic education ‐ participants were fitted with a custom wrist‐hand orthosis that maintained the wrist in a neutral posture, and was worn at night for 6 weeks. Participants received instructions in how to reduce ergonomic stressors in the work and home environments by viewing a 20‐minute video on CTS and ergonomic risk factors. The focus of the video was industrial ergonomics and the prevention of repetitive strain disorders. Group 2 ‐ergonomic education alone: Ergonomic education alone via the same 20‐minute video on CTS and ergonomic risk factors presented to participants in the intervention group
Outcomes	Outcomes assessed at baseline, and 3, 6, and a mean of 12 months (range 7 to 15 months) follow‐up (after the end of treatment) BCTQ Symptom Severity Scale (1 to 5; higher is worse) Elbow and forearm, and wrist, hand and finger discomfort using a 30‐day worst‐discomfort rating on a 0 to 10 VAS Surgical rates for CTS Nerve conduction: median nerve sensory peak latency (msec), median nerve sensory amplitude (µv), median‐ulnar peak latency difference (msec) Data in Occupational Health and Safety administration logs, plant medical records, disability records, days of work missed due to upper extremity problems, and workers’ compensation status or work restrictions collected from computerised records Splint usage and satisfaction (only in the intervention group) using a questionnaire administered at the end of the 6‐week treatment period
Funding	Supported in the whole by joint funds from the United Auto Workers (UAW) and General Motors (GM) National Joint Committee on Health and Safety "No commercial party having a direct interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated."
COI	Not reported
Notes	According to the trial authors, half the participants did not complete the questionnaires at 3‐month and 6‐month follow‐up, so no data from these time points were reported. The authors did not report numbers regarding adherence to splint use.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quote: "Subjects were randomized to either a treatment or a control group, depending on whether the last digit of their Social Security number was odd or even." Comment: The trial authors used a non‐random component in the sequence generation process.
Allocation concealment (selection bias)	High risk	Quote: "Subjects were randomized to either a treatment or a control group, depending on whether the last digit of their Social Security number was odd or even. Subjects were not informed of the sequence for random allocation nor were they told to which group they were assigned until after consenting to participate." Comment: The trials authors did not adequately conceal the treatment allocation until interventions were assigned, as a non‐random process was used.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "Subjects were not blinded to their treatment, and the primary outcome measure was a self‐reported symptom severity score." Comment: Participants were not blinded to treatment allocation.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "The nerve conduction data were collected at baseline and at the 12‐month follow‐up. Subjects reported to the medical department to have the testing done during regular work hours, and the person doing the testing was blinded to the treatment assignment." Comment: Since participants themselves assessed participant‐reported outcomes and they were likely to be aware of their allocated treatment in this study, we rated the risk as high.
Incomplete outcome data (attrition bias) 3 months or less	High risk	Quote: "Data collection was incomplete at the 3‐ and 6‐month follow‐up periods. Subjects were contacted by a study site coordinator and were reminded to fill out the questionnaire, but about half of the subjects did not complete the 3‐ or 6‐month questionnaires. The trend in outcome measures at 3 and 6 months was similar to the results at 12 months." Comment: Data not complete for all outcomes, with no explanation as to how this may have impacted on the data reported
Incomplete outcome data (attrition bias) After 3 months	High risk	Quote: "The 12‐month follow‐up data are presented because they represent a more complete data set...The 12‐month follow‐up was actually a range of follow‐up times, with an average of 12 months and a range of 7 to 15 months." Comment: Data not complete for each outcome, with no explanation as to how this may have impacted on the data reported
Selective reporting (reporting bias)	Unclear risk	Comment: The results of participant self‐reported outcomes reported; however, protocol not available
Other bias	Low risk	Comment: No other sources of bias identified