Are Ergonomic Interventions Effective and Worth the Cost in Preventing or Reducing MSDs?
There is general consensus on the widespread and multifactorial nature of musculoskeletal pain and musculoskeletal disorders (MSDs) in modern society. This wide spread nature is associated with high costs for society and for individual companies due to loss of productivity and reduced performance of workers with these problems. For instance recent data show that in the 27 EU countries, 25％ of workers complain of backache and 23％ report muscular pains. In practically all these EU countries MSDs are the main cause of absence from work and in some countries 40％ of the costs of workers compensation are caused by MSDs. This can mount up to 1.6％ of the gross domestic product of the country (European Agency for Safety and Health at Work, Work-related MSDs prevention report).The reduced company profitability due to these disorders is not well documented with empirical data. In order to deal with these problems an array of preventive ergonomic interventions or ergonomic work place adaptations -for those with starting problems-, are widely applied. It seems plausible that, given this combination of a prevalent problem, high costs and widely applied interventions, there would be ample knowledge among employers and employees which of these interventions is the most effective and in particular the most cost effective to reduce MSDs. Unfortunately this is not the case. Robust knowledge on cost effectiveness can only be based on comparable multiple high quality studies in which the effect of ergonomic interventions on prevention or reduction of MSDs is rigorously evaluated. In addition, detailed knowledge of the major risk factors and prognostic factors is essential, since effective preventive interventions will only contribute to a solution of the problem when they are targeted to strong and prevalent risk factors (or a combination of such factors). In addition, reduction of recurrence and aggravation of MSDs and enhancement of return to work after absence due to MSDs, will only succeed with interventions targeting strong and prevalent prognostic factors and obstacles for work resumption. Unfortunately the data on dose response relationships between physical load and occurrence or prognosis of MSDs is still not in sufficient detail. It is therefore hard to know which aspects of physical exposure (intensity, duration, pattern etc) need to be targeted in interventions, and how large the exposure reduction should be in order to have a fair chance of a reduction in MSDs. Information on effectiveness of interventions is hard to obtain other than with a (quasi) experimental study design such as a randomised controlled trial. To summarise the evidence ideally a meta analysis or otherwise a systematic review of such studies should be conducted. It has been suggested that the criteria, as derived from clinical studies, to judge the quality of studies and synthesize the evidence of effectiveness, are not fit for evaluation of (complex) ergonomic interventions. Suggesting that studies on effectiveness of ergonomic interventions are often too harshly judged as being of low quality and that RCTs are hardly feasible in this field and that rigorous synthesis of the evidence cannot or should not be done. In my view several recently published studies show that this is not a tenable assertion. High quality evaluation studies of ergonomic interventions can and have been done. For instance in the last five years, quite a few high quality studies on effectiveness of ergonomic interventions aimed at preventing or reducing MSDs have been reported and systematically summarized in quite a few informative reviews (Heymans et al 2004, Silverstein and Clark 2004, Tveito et al 2004, Van Poppel et al 2004, Van der Molen et al 2004, 2005, Ammendolia et al 2005, Franche et al 2005, Burton et al 2006, Bos et al 2006, Brewer et al 2006, Henrotin et al 2006, Martimo et al 2006, Verhagen et al 2006, Boocock et al 2007, European Agency for Safety and Health at Work 2007 a,b, Brox et al 2008, Rivilis et al 2008). These recent reviews show that the investments in high quality evaluation studies begin to pay off. For instance Rivilis et al (2008) conclude in their review that 12 studies that were rated as medium or ‘higher quality provide partial to moderate evidence that participatory ergonomic interventions have a positive impact on musculoskeletal symptoms and on reducing injuries and workers compensation claims, and on a reduction in lost days from work or sickness absence. Partly due to the large variety in applied interventions, for instance redesign of physical environment (i.e. adjusting tables and chairs) or redesign of working aids and tools, lifting and transfer aids for manual material handling or organizational and administrative interventions (i.e. modified work), there is still only a limited number of high quality studies on the evaluation of effectiveness available for each of these interventions. Unfortunately, this situation is responsible for the conclusion that there is insufficient evidence for the effectiveness of most ergonomic interventions. However, for several intervention categories, one or two additional high quality studies would alter this situation and make more definitive conclusions on effectiveness possible. Studies that also provide data on the associated costs and benefits or costs and effects (i.e. reduced pain) are still very scarce and often of limited quality (Tompa et al 2006). However, in the most recent systematic review of disability management interventions with economic evaluations, Tompa et al (2008) found moderate evidence that interventions with an ergonomics and education component were worth undertaking based on their financial merits. That conclusion was based on five studies. The above short presentation of the current state of the art on effectiveness of ergonomic interventions shows that in recent years a lot of progress has been made. It also shows that applying the RCT paradigm in ergonomics yields promising results. In addition, having evaluative criteria for quality of research also disciplines other researches in the design phase of their studies, which will strongly enhance comparability and thus the possibilities to synthesise the evidence across studies and draw some firm conclusion. Although of course the limitations of very rigorously conducted systematic reviews that simply rate, categorise and count should be sufficiently recognised. There is a lot to learn from more qualitative studies and summarised results but in addition to this type of more rigorous evidence synthesis as advocated above.
Paulien M. Bongers
TNO Netherlands
国际会议
17th World Congress on Ergonomics(第十七届国际人类工效学大会)
北京
英文
1-2
2009-08-09（万方平台首次上网日期，不代表论文的发表时间）