Gerr 2005.
Methods | RCT. Randomisation occurred following evaluation of workplace and ergonomic variables. The use of a random number table assured that each subject entering the study had an equal probability of being assigned to each of the 3 groups. Randomisation was done in blocks of 6 to assure equal numbers of participants in each of the study groups. | |
Participants | A person eligible for inclusion in this study was: a newly hired worker who: anticipated using a single computer workstation for 15 hours or more per week and anticipated using a computer workstation for at least as many hours per week as in his/her previous job working at insurance and financial companies, food product producers, and universities in metropolitan Atlanta, GA, US who had reported experiencing arm or hand symptoms during the week prior to intervention. Of the 447 eligible for health screening, a total of 379 individuals were eligible for inclusion into 1 or both cohorts (those who did not report experiencing arm or hand pain and neck or shoulder pain during the week prior to the study. 375 people were randomised into the arm and hand cohort and 356 were randomised into the neck and shoulder cohort. |
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Interventions | The study compared alternate intervention, conventional intervention, and no intervention A study staff member reconfigured the subject's workstation if the subject was randomly assigned to either the alternative or conventional interventions (groups A or B). Verbal and written instructions describing the desired posture were provided to all group A and B participants. At 3 days and 1 week after the intervention, study staff returned to the participant's workplace to check on continued maintenance of the posture. If the posture had changed from the intervention, additional workstation changes were made and additional instruction given. Group A: alternate intervention The workstation was adjusted according to the following configuration:
Group B: conventional intervention The workstation was adjusted according to the following configuration:
Group C: no intervention Participants instructed to continue keying in their usual posture and no changes were made to their workstations. |
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Outcomes |
Primary outcome Time to event: symptoms of pain or discomfort ‐ participants were classified as having experienced musculoskeletal symptoms if they (1) reported musculoskeletal discomfort on any day of the week with a severity of ≥ 6 on the 0 to 10 VAS or (2) reported musculoskeletal discomfort on any day of the week for which they took medication (over‐the‐counter or prescription). Study participants were followed for each outcome separately until they became symptomatic (censored). Development of a symptom in one anatomic area did not stop the collection of data for the other anatomic area. Two separate, overlapping cohorts were then defined to examine separately the risks of neck or shoulder symptoms and the risks of arm or hand symptoms. Secondary outcome Compliance: using a standard checklist, each workstation was evaluated for presence of specific items (e.g. mouse or other pointing device), and the adjustability of specific equipment. Following completion of the checklist, dimensional and angular measurements (e.g. seated elbow height, table surface height, keyboard inner elbow angle) were recorded. |
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Notes | Gerr 2005 consisted of two overlapping cohorts. The effect of the intervention was assessed as arm/hand and neck or shoulder pain. | |
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Low risk | The use of a random number table assured that each subject entering the study had an equal probability of being assigned to each of the 3 groups. Randomisation was done in blocks of 6 to assure equal numbers of participants in each of the study groups. |
Allocation concealment (selection bias) | Unclear risk | No information on allocation concealment. |
Blinding of participants and personnel (performance bias) All outcomes | High risk | There was no mention of blinding and the methods of intervention consisted of 2 distinct workstation and postural interventions. |
Blinding of outcome assessment (detection bias) Musculoskeletal disorders | High risk | Outcomes consisted of subjective symptoms measured with a checklist. |
Incomplete outcome data (attrition bias) All outcomes | Low risk | Participants contributed data to their assigned intervention group regardless of compliance (i.e. data were analysed by ITT). |
Selective reporting (reporting bias) | Low risk | Key findings: there were no significant differences in the incidence of musculoskeletal symptoms among the 3 intervention groups. |
Other bias | High risk | Large number of drop‐outs. "There were a large number of drop‐out/lost to follow‐up in arm/hand cohort – 147 (41% of those followed) were lost during the six month follow up period … No differences were observed in dropout rates (i.e. incomplete follow‐up) across the three intervention groups". Although the drop‐out rates were similar across the 3 randomised groups, there were a large number of drops‐outs in each group (36 to 42 across all 6 groups) for which the authors did not provide a reason. |