The underlying purpose of this article and position paper is to achieve evidence-based recommendations on prevention of work-related MSDs. Such prevention can take different forms (primary, secondary and tertiary), occur at different levels (i.e. in a clinical setting, at the workplace, at national level) and involve several types of activities.
Members of the ICOH’s SC on MSDs and other interested scientists and members of the public recently discussed the scientific and clinical future of prevention of (work-related) MSDs during five round-table sessions at two ICOH conferences, in Cape Town, South Africa, in 2009 and in Angers, France, in 2010. The focus of the sessions was to discuss new developments that had taken place since 1996 with regard to the measures and classification systems used in research and practice, and agree on what is needed in the near future.
The discussion focused on three questions: At what degree of severity does musculoskeletal ill health, and do health problems related to MSDs, in an individual worker or in a group of workers justify preventive action in occupational health? What reliable and valid instruments do we have in research to distinguish ‘normal musculoskeletal symptoms’ from ‘serious musculoskeletal symptoms’ in workers? What measures or classification system of musculoskeletal health will we need in the near future to address musculoskeletal health and related work ability?
Forty-five minutes were allocated to each question. Three to four members of the SC were asked to prepare their views in advance, to start the discussion with expert opinions from different parts of the world. Immediately following the discussions, some statements were prepared by the organizers of the round-table discussions (J.S., M.H., F.V., R.B.) and discussed in a fourth round-table session. Four new, agreed-upon statements were extrapolated from the discussions and are given below.
1. Musculoskeletal discomfort that is at risk of worsening with work activities, and that affects work ability or quality of life, needs to be identified.
Unpleasant sensations from the musculoskeletal system are experienced by everyone and can be adaptive in circumstances when muscle soreness is experienced after physical training, for example. In prevention of work-related MSDs, we need to assess musculoskeletal symptoms that have a potential of affecting workers’ health in a negative way. Symptoms at risk of worsening (e.g. paraesthesia as a first phase before pain may be present in entrapment syndromes) which reduce work ability or impair quality of life should be targeted. Questions like ‘What probabilities should be avoided?’ are likewise relevant. The core outcome domains recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) [16
] for clinical trials of chronic pain can provide some guidance. These are: pain, physical functioning, emotional functioning, global wellbeing, symptoms and adverse events, and participant disposition. Pain that is worsening with work activities should be detected since this will probably influence productivity in addition to affecting quality of life. One idea that emerged involves a measure that couples pain with a measure of functioning. Examples of reliable and valid instruments used today to target part of these aspects are: the Work Ability Index (WAI; http://www.ttl.fi
], the Work Limitation Questionnaire (WLQ) [18
] and the Work Role Functioning Questionnaire (WRFQ) [19
]. Furthermore, the Nordic Musculoskeletal Questionnaire (NMQ) [20
] and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire [22
] aim specifically at musculoskeletal symptoms and functioning.
2. We need to know our options of actions before identifying workers at risk (providing evidence-based medicine and applying the principle of best practice).
Identifying workers at risk for developing MSDs or worsening of MSD symptoms related to work involves ethical issues. A management plan on how to give feedback to the worker and management (as well as unions and other stakeholders) should be considered before starting any health screening or surveillance of workers. The ICOH ethical guidelines state that we need to know our options of actions before identifying workers at risk. It is important to make some judgement about which symptoms are related to work exposures in order to predict what will get worse with work exposures and what will get better if work exposure is decreased.Action on individual resources or work demands should follow screening, using reliable and valid exposure instruments [6
]. Criteria for addressing symptoms can be derived from knowledge of the prognosis, and of the effect of the symptoms on productivity and quality of life. It may be too early to recommend specific criteria or cut-off levels to identify workers at risk. However, examples from practices from different countries in setting criteria at the individual level that was asked for and mentioned in our discussion are: using a visual analogue scale (VAS) to assess pain and setting the criteria to 50
mm to identify ‘severe’ complaints/disorders. In Finland a rating of 70–100 is regarded as justifying intervention [23
]. In France, a score of ≥50 is seen to indicate serious symptoms. Another example of action taken is when musculoskeletal complaints are the main health problem in workers scoring <6 for poor work ability on the 11-point scale of the Finnish WAI [24
]; sometimes only the first item of the WAI is used and action can be taken based on that score [25
]. In the Netherlands, an example of another type of health complaint, fatigue, was mentioned at the group level when the organizational or departmental criterion for action to be taken was defined as more than half of the workers scoring above the cut-off score on the Need for Recovery (NFR) after work scale [26
3. Classification systems and measures must include aspects such as the severity, frequency, and intensity of pain, as well as measures of impairment of functioning, which can help in prevention, treatment and prognosis.
To date, several classification systems for MSDs have been proposed and published in the literature, mainly aimed at defining diagnostic criteria. This is probably due to the importance of diagnosis for understanding the underlying pathological process as a prerequisite for the management of prevention and treatment of diseases.Even when the pathogenesis of illnesses is unclear, a case definition can be considered a useful way of classifying cases so that illnesses that share the same causes or a similar prognosis and response to treatment can be managed or prevented more effectively [27
]. This links to the first statement “Musculoskeletal discomfort that is at risk of worsening with work activities, and that affects work ability or quality of life, needs to be identified”. The case definition for a disorder may vary according to the purpose for which it is being applied. Even broad, i.e. non-specific, case definitions may usefully identify workers at risk of progressing to more serious outcomes (see, e.g., [28
].However, it is well recognized that it may not be sufficient to merely explore physical symptoms when nothing is known about the impact of the symptoms on functioning or work ability. The International Classification of Functioning (ICF) is an example of a classification system addressing functioning, disability and health in individuals and groups of individuals (http://www.who.int/classifications/icf/en/
).One of the challenges for the scientific community that was agreed upon is to gain better understanding of the effect of the different aspects of the work environment on the functioning of the worker with certain MSD problems. We will then be able to propose better solutions to address these problems in time.
4. We need to be aware of economic and/or socio-cultural consequences of classification systems and measures.
The scientific community should be aware of the societal impact of communicated work-related health problems. Legal disputes over compensation may affect work ability [29
]. In Australia repetitive strain injuries (RSI) was debated in society during the 1980s which may have hampered adequate prevention at the time [30
]. Reaction to musculoskeletal trauma may be influenced also by ethnicity [31
]. We know from practised systems of defining occupational diseases that estimates of incidences may differ 60-fold between the different European Union (EU) countries. The consequences of classification systems and measures need to be elucidated and evaluated to minimize the risk of adverse effects on the individual worker and on society.