Brisson 1999.

Methods	Cluster RCT. Workers were assigned to the experimental or reference group (no intervention) on the basis of the units in which they worked. 40 administrative and geographic units were randomised to the experimental group or reference group. The units were stratified before randomisation on the basis of the number of clerical workers (< 20 and ≥ 20) and type of services (administrative and teaching) in order to ensure equal distribution of these features in each group.
Participants	The study population composed of workers employed in a large university (90%) and in other institutions involved in university services (10%). Eligible workers were those working 5 hours or more per week with a VDU. 627 workers (81% of the people eligible at baseline) participated in both data collection periods (baseline and 6 months). They consists of: PRECEDE intervention group (n = 284); reference/no intervention group (n = 343).
Interventions	The study compared PRECEDE intervention vs no intervention. PRECEDE intervention group The ergonomic training programme was developed according to the PRECEDE model. “The objective of the programme was to act on characteristics of the work environment and the workers that determine behaviour in order to motivate and to enable the workers to improve the ergonomic features of their workstation. Predisposing factors relate to knowledge, beliefs, attitudes, and values; enabling factors relate to skills and material resources; and reinforcing factors relate to support provided by the environment.” The programme targeted the following 3 types of behaviour: adjusting the postural components of the workstation correctly; adjusting the visual components of the workstation correctly; and organising work activities in a preventive manner The programme composed of 2 sessions of 3 hours each with a 2‐week interval The sessions involved demonstrations, simulations, discussions, and lectures. In addition, each worker had to do a self‐diagnosis of his (her) workstation using a photograph taken of him (her) at work before the programme started. Each session was presented to about 15 workers with their supervisor at one time. The presence of the supervisor aimed at providing an organisational environment that was supportive of actions taken by the workers. The 2‐week interval allowed the workers to apply knowledge and skills learned at the first session and to return to the second training session with questions and experiences to discuss. The trainers were 4 occupational health and safety professionals working for the employer and 1 occupational health and safety union representative. Reference/no intervention group The reference group did not receive the training until the completion of the study
Outcomes	Primary outcome Neck‐shoulder and hand‐wrist musculoskeletal symptoms were assessed using a self‐administered questionnaire and by physical examination by physician. The measurements were performed 2 weeks before and 6 months after the intervention in both groups. The prevalent MSDs on the questionnaire were defined as those that were present on 3 days or more during the last 7 days and for which the intensity of pain was greater than half the visual analogue scale among subjects with no history of inflammatory disease or acute injury at the relevant anatomical site. The physical examination by physician was performed on workers who reported symptoms meeting the case definition. The physical examination was conducted according to a standard protocol by a trained occupational therapist blinded to the participant's assigned group. The physical examination was performed 2 to 5 weeks after the completion of the self‐administered questionnaire. Secondary outcome Compliance with the intervention
Notes	The information for the neck‐shoulder and hand‐wrist musculoskeletal symptoms was available for the 2 groups (i.e. < 40 years and ≥ 40 years) combined comparing before and after intervention, and for 3 anatomical regions combined (neck or shoulder, wrist/hand and lower back) comparing intervention and reference before and after intervention. No information was available for neck or shoulder and wrist or hand alone comparing the effect of intervention and reference group. The author provided the additional data; i.e. Intracluster Correlation Coeficient (ICC), prevalence of musculoskeletal symptoms for all subjects for each site collected by questionnaire at baseline, and prevalence of musculoskeletal symptoms for all subjects for each site collected by medical examination at baseline and follow‐up.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	There was no information on sequence generation. The method for randomisation was clearly described.
Allocation concealment (selection bias)	Unclear risk	There was no information on allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants were not blinded to the allocation as the intervention consisted of training.
Blinding of outcome assessment (detection bias) Musculoskeletal disorders	High risk	Although the physical examination was performed by trained occupational therapists blinded to the subjects' assigned group, the examination was only performed on workers who reported symptoms meeting the case definition which was based on self‐reporting/subjective symptoms.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Although there was no mention of ITT, the percentages of participants were high at each measurement (88% and 94%). And according to the author "The percentages and reasons for non‐participation were comparable in the experimental and reference groups".
Selective reporting (reporting bias)	Low risk	All outcomes were reported in the results.
Other bias	High risk	There was no information on baseline characteristics comparing the 2 groups, so the success of randomisation could not be ascertained.