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Re: Response to Markku Seuri and Jukka Uitti

We thank Markku Seuri and Jukka Uitti for their interest towards our article [1] and for raising the topics for discussion in OEM (eLetter posted 16 October).

Concerning the first topic, the intervention in the RCT1 among the High Risk subjects consisted of 1) personal feedback of the health survey results and 2) an invitation to a consultation at their local occupational health service (OHS). The main purpose of the OHS consultation was the construction of an action plan, and if appropriate, referral to a further consultation by a specialist or psychologist. Of the subjects in the intervention group (n = 209), 142 (68%) attended the consultation at OHS. 50 did not attend for unknown reasons. The employment had terminated with 17 subjects during the follow-up. Of the attendees, five refused further examinations or interventions, and the OHS professionals had considered that eight subjects did not warrant further actions. Eventually 129 subjects ended up receiving something: health advice (n=106), referral to consultation or hospital outpatient clinic (n=64), or a group intervention at the OHS (n=6), in different combinations. As 64 subjects were referred to specialist treatment, it is reasonable to assume that they had had clinically significant disorders. Moreover, of the 142 subjects who visited OHS, 72 (51%) had not received earlier treatment at OHS for the respective reasons for belonging to the High Risk group. With the health survey and subsequent invitation to OHS we obviously succeeded in capturing many workers with underlining health problems that had not been properly attended to. We discuss this and other possible mechanisms of the effectiveness in more detail in our recently published paper concerning the cost-effectiveness of the same intervention [2]. We preferred not to present the on-treatment subgroup analysis, as it was not stated in our study protocol. However, we have done the analysis: among those 50 subjects that did not attend the intervention sickness absence tended to increase from 18 days to 25 days, while among those who attended the intervention sickness absence days at baseline and follow up were the same, 17 days. This provides further support to the view that the targeted OHS intervention was indeed accountable for the effectiveness rather than the feedback letter.

As regards the second point we are somewhat confused. We do not write about “the reduction of sickness absence in the intervention group” in the article. As we present in the results, the mean, median and total sickness absence days increased, and the proportion of subjects with zero absence decreased in the control group. No change took place in the mean, median and total sickness absence days, or in the proportion of subjects with zero absence in the intervention group. Based on this we concluded that the OHS intervention was effective in controlling work loss. Nothing very extraordinary happened in the company either: the mean of sickness absence days in the study cohort increased from 10 to 12 days (i.e., one per cent unit) and the increase mainly took place in the control group arm in the High Risk group: the increases were 0.2, 0.7 and 2.6 per cent units in the Low Risk, Intermediate Risk and High Risk groups, respectively. The increase in sickness absence in this specific company did not differ from the industry sector. However, as we write in our paper [1], future research should address the question of whether the same intervention approach is effective in different occupational settings and professional groups. The evidence on effectiveness of interventions undertaken by occupational health care units in reducing sickness absence among high risk employees is meager. We do hope that our randomized controlled trial will encourage occupational health clinicians and scientists to undertake randomized trials and increase the evidence base of the field.

1 Taimela S, Malmivaara A, Justen S. et al. The effectiveness of two occupational health intervention programs in reducing sickness absence among employees at risk. Two randomised controlled trials. Occup Environ Med published online 6 Aug 2007;doi10.1136/oem.2007.032706.

2 Taimela S, Justen S, Aronen P. et al. An occupational health intervention program for workers at high risk for sickness absence. Cost- effectiveness analysis based on a randomised controlled trial. Occup Environ Med published online 12 Oct 2007 doi:10.1136/oem.2007.033167

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Re: What was the effective interventio?

Taimela et al published the results of two RCTs 1. Trials are validly conducted, but two points need further consideration. Firstly, one should ask what was the effective intervention. Occupational health carried out three actions. Firstly they identified the high-risk employees, secondly they sent a letter of the intervention program only to those in the intervention group and thirdly consultations were given to those willing to participate (participation rate only 68%). The consultations led health advice, consultation or group intervention. The analysis was conducted according to the principle of intended to treat. No results concerning those actually treated were given. The effective treatment was not necessarily what the occupational health did with the patients but the letter that was sent only to the intervention group. This letter obviously increased personal consciousness of the high-risk behaviour and may by itself act as intervention for the observed change. More information about the effective action would have been available if the results were given by the principle of actually treated. Secondly, the authors write about “the reduction of sickness absence” in the intervention group. This is not quite so, since the mean number of sickness absence days at baseline was 19.7 per year and 19.3 during the follow-up. This is not a reduction. However, the number of sickness absence days increased in the control group from 17.9 to 29.9 days per year and in the study population at large from 18.8 to 24.6 days per year. At the same time the general increase in sickness absence in Finland grew only less than 0.5 per cent. Something very extraordinary happened in the studied company and that leads one to ask how well the results can be applied in companies of stabile level of absenteeism. 1 Taimela S, Malmivaara A, Justen S. et al. The effectiveness of two occupational health intervention programs in reducing sickness absence among employees at risk. Two randomised controlled trials. Occup Environ Med published online 6 Aug 2007;doi10.1136/oem.2007.032706.