Voerman 2007

Methods	The study is a randomised controlled trial using a block‐randomisation design consisting of two groups. Both groups received an intervention. The intervention period lasted for four weeks. The study was performed in the years 2003 to 2005 in the Netherlands (area of Enschede) and in Sweden area of Goteborg.
Participants	Computer workers like job counsellors and medical secretaries were approached by telephone and announcements, and sent a screening questionnaire. To be included in the study the participants had to work at least 20 hours a week and have had perpetuating work‐related complaints in the neck and/or shoulder region for at least 30 days during the last year. Excluded were participants who reported pain in more than three body regions, who suffered from severe arthrosis or joint disorders, who were using muscle relaxants, or if they reported other complaints in the upper extremity not related to computer work. The participants were all female workers over 45 years old. Mean age was 52 years in intervention group 1 (N=42) and 50.7 years in the intervention group 2 (N=37). Mean working hours per week was 32.8 in both groups. Participants were recruited between March 2003 and June 2005. Total number of participants recruited is not stated, but 79 workers met the inclusion criteria, of which 65 participants completed the study at six months follow‐up. Forty‐one participants were recruited in Sweden, while the remaining 38 participants were recruited in the Netherlands.  MSD was assessed as pain in neck, shoulder and upper back for at least 30 days during last year. The amount of participants with complaints and trouble in neck last year (measured from baseline) was 92.9% in the intervention group 1 and 91.9% in the intervention group 2.
Interventions	Intervention group 1: Myofeedback and ergonomic counselling.The participants received ambulant myo‐feedback training combined with ergonomic counselling. Immediately after baseline, participants were given a myo‐feedback device and they were explained the working mechanism and background of the myo‐feedback training. They were instructed to respond to the feedback by relaxation. The participants wore the device for four weeks, for at least eight hours a week, (distributed over two hours a day and two days a week as a minimum), while performing their regular work. During the weekly visits by their therapist the electronic data from last week were scrutinized and discussed to give the participants insight in their relaxation patterns and to identify possible situations of concern. The content of ergonomic counselling intervention is described below. Intervention group 2: Ergonomic counselling. Participants received four weeks of intervention during which they kept a diary of activities and pain intensity scores. In this period they were visited weekly by their therapist. The first visit comprised an ergonomic workplace investigation by means of the risk inventory. This checklist contained questions to evaluate work tasks, working hours, work load, work station, and working methods. Based on the outcome, possible improvements were discussed with the participants. With regard to the work station, the focus was primarily on modifying the existing work station rather than providing new equipment. The remaining visits were used to further discuss the ergonomic aspects, the consequences of possible ergonomic adjustments etc. This was done according to a manual to guarantee a uniform intervention.
Outcomes	Measurements were performed at baseline, immediately after intervention, and at three months and six months after the intervention. The outcomes were: Pain intensity: Pain intensity in the neck, shoulder (left and right), and upper back at time of the measurement was assessed by means of four Visual Analogue Scales. Participants were instructed to rate their subjectively experienced level of pain intensity at that moment for each body region. Pain intensity was scored on a ten cm scale ranging from 'no discomfort at all' to 'as much discomfort as possible'. Disability: The level of subjectively experienced disability was assessed with the Pain Disability Index, a self‐rating scale that measures the impact of pain on the abilities to participate in life activities. Disability was scored on an eleven‐point scale ranging from 'not disabled' to 'fully disabled'.
Notes	Additional information about the Swedish branch of the study was found in another publication (Larsman 2009). We were able to reach the second author, who respond to our questions concerning missing information.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Quote: “Block‐randomisation was used to assign subjects to either Mbf or Ec. When a new group of subjects started the intervention, half of them were assigned to Mfb and half of them were assigned to Ec”. (MbF is intervention group 1 and Ec is intervention group 2). When asked, second author informs that randomisation was performed using a random function in Excel. Using a computer random number generator is an adequate method of sequence generation.
Allocation concealment?	Unclear risk	Despite thorough explanation from second author, we are not convinced that the allocation was adequately concealed in the Dutch branch of the study.
Blinding? All outcomes ‐ participants?	High risk	Quote: "The character of the intervention made blinding of the therapists and the subjects to the intervention impractical. To prevent from information bias, subjects were informed that the aim of the study was to compare the effects of two interventions and that there was no evidence favouring one of these interventions”. Participants were not blinded to the intervention.
Blinding? All outcomes ‐ providers?	High risk	Care providers were not blinded to the intervention.
Blinding? All outcomes ‐ outcome assessors?	High risk	When asked, the second author confirms that in Sweden the outcome assessors never met the participants. However, in the Dutch branch of the study the outcome assessor and care provider was the same person. Hence, all outcome assessors were not blinded to the intervention.
Incomplete outcome data addressed? All outcomes ‐ drop‐outs?	Low risk	According to diagram 1 in the article, 79 participants were included in the study and 65 participants completed the study at six months follow‐up. This gives a drop‐out rate of 18%, which is acceptable.
Incomplete outcome data addressed? All outcomes ‐ ITT analysis?	Low risk	According to second author all randomised participants were analysed in the group to which they were allocated.
Free of selective reporting?	Low risk	All outcomes are reported thoroughly. Besides, both groups were given an occupational intervention and no differences were found between the groups. Hence, there is no reason to suspect selective reporting.
Similarity of baseline characteristics?	Low risk	Quote: “Despite extensive standardisation, the recruitment of subjects in two different study groups (Sweden and the Netherlands) resulted in heterogeneity of the subject populations with regard to age, working hours, seniority, and working posture. To correct for this, the factor study group was considered a confounder need to control for during analyses”. Since the baseline imbalance was corrected for in analyses, we consider this criterion to be met.
Co‐interventions avoided or similar?	Low risk	When asked, the second author confirms that co‐interventions were equally distributed between the two intervention groups.
Compliance acceptable?	Low risk	Second author writes that in intervention group 1 the participants had to wear the myo‐feedback device at least eight hours a week for four weeks; in other words they had to comply. The participants in intervention group 2 were considered to comply if they took part in all weekly meetings, and all participants did so. Hence, compliance was acceptable in both groups.
Timing outcome assessments similar?	Low risk	According to diagram 1 in the article, the timing of outcomes assessment was identical in the two groups.