von Thiele 2008

Methods	Cluster RCT. Workplaces with a high (n = 3) and a low (n = 3) sickness absence were matched according to the number of employees. The matching resulted in 3 pairs that were randomly allocated to 1 of the 3 intervention groups
Participants	Participants consisted of female employees from 6 workplaces in a large public dental healthcare organisation in Stockholm, Sweden. In all, 197 women employed at the 6 workplaces were invited to take part in the study. Of the women invited, 195 volunteered to participate
Interventions	The study compared 3 intervention arms Reduced work hours group: full‐time weekly hours were reduced from 40 hours/week to 37.5 hours/week (reduced by 2.5 hours/week). For part‐physical exercise and reduced work hours group, time for exercise/reduced work hours were set at 2 hours for those working 30 to 39 hours/week (39% of employee), 1.5 hours for 21 to 29 hours/week (14%), and 1 hour for < 20 hours/week (2%). Mandatory physical activity involved exercise of medium‐ to high‐intensity corresponding to 55% to 89% of the person's maximum heart rate. The employees were free to choose any type of physical exercise Physical‐exercise group: full‐time employees with whom 2.5 hours weekly work hours were allocated to mandatory physical exercise on 2 different days Reference group: no intervention
Outcomes	Primary outcome: musculoskeletal symptoms in the upper extremities: neck, shoulder, and hand‐wrist were measured with the Standardized Nordic questionnaire. "For all items, the respondents were asked to indicate whether they had experienced symptoms or pain during the past 6 months." Sum scores were then computed. These ranged from 0 to 3, a high score indicating more symptoms Workability was measured using a single item. The respondents were asked to rate their current work ability as compared with their work ability at its best on a 10‐point scale ranging from 'completely lacking work ability' (1) to 'work ability at its best' (10)
Notes	This report consists of 2 interventions (physical exercise and reduced work hours) and 1 control (reference group). For this review we only considered reduced work hours compared to reference group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	There was no information on sequence generation: "three workplaces with a high level of sickness absence and three with low levels, each employing at least 25 persons, were selected. Workplaces with a high and a low sickness absence were matched according to the number of employees. This matching resulted in three pairs that were randomly allocated to one of the following three groups"
Allocation concealment (selection bias)	Unclear risk	There was no information on allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	High risk	The was no blinding. This study examined the health‐related effects of 2 work‐site interventions, physical exercise and reduced work hours, on women employed in dentistry
Blinding of outcome assessment (detection bias) Musculoskeletal disorders	High risk	The outcomes were assessed as subjectively reported musculoskeletal symptoms
Incomplete outcome data (attrition bias) All outcomes	High risk	There was no mention of ITT. The number volunteered (195 people) and analysed (177 people) was different. The distribution of participants in each group was uneven (physical exercise = 62 women, reduced work hours = 50 women, reference group = 65 employees/women). There was no description or comment on the unequal distribution. The total number of participants in each group who responded to the question on upper extremity disorder were different compared to the initial participants (exercise = 58 women, reduced hours = 43 women, reference = 59 women)
Selective reporting (reporting bias)	Low risk	All data were reported
Other bias	Unclear risk	Differences between workplaces may have influenced the intervention