Observation-based tools for assessment of risk for musculoskeletal disorders

Introduction

The aim of this document is to provide a guide for the selection of easy-to-use, usable and research-based assessment tools for the assessment of risk for work-related musculoskeletal disorders (WMSDs) during the SLIC Campaign 2022 ‘Healthy Workplaces Lighten the load’. This guide includes observation-based assessment tools that can be used without more advance technical measurement instruments. The target group for the guide is Labour Inspectors and Occupational Safety and Health specialists but also Employers and Safety Representatives can gain from the document.

The assessment tools are aimed to support the risk assessment process, but do not usually cover all of the relevant risk factors in the targeted work. It is important to have an adequate knowledge of the limitations and restrictions of the tool(s) used, and to apply a suitable sampling strategy so that the time period, type of task and the selection of employees correspond to a fair representation of the total job or work tasks. A representative sampling strategy should usually include both average exposures as well as (infrequent) peak exposures. Given the limitations of each assessment tool, the assessment strategy should also involve (self) reports from the employees performing the work being assessed.

Only a few of the currently available assessment tools have demonstrated its ability to predict an increased risk of WMSDs in longitudinal studies (i.e., predictive validity)^[1]. Also, many tools often signal that a low exposure level is equal to a low risk of WMSDs. For most of the tools, caution should be applied when interpreting the so-called “risk levels", as these usually have not been demonstrated in the peer-reviewed literature, and if they have, these associations with WMSDs represent the assumed risk on group level rather than at the individual level. Given the lack of research-based tools that have demonstrated predictive validity, the selection of tools included here mainly include tools that have not demonstrated predictive validity but may still be valuable for assessment of exposures that may have adverse health effects. Additionally, the tools included build on research and have been developed by research groups with expertise in the related research field. In addition of predictive validity, the applied tools should also be reliable in the sense that its results can be repeated if performed by the same or other assessors (i.e., intra- and inter reliability)^[1][2].

Usually it is advisable to include the three main exposure dimensions in the assessment:

• magnitude: e.g., mass, force, torque,
• duration: e.g., hours per workday, or continuous time without a break, and
• frequency/repetition: e.g., how often an exertion is carried out, such as times per minute or hour.

Additionally, it is advisable to also include recovery periods such as shorter or longer periods allowing recovery.

Note that all assessment tools do not include these fundamental exposure dimensions, or only partly include them. In those cases it may be needed to complement the assessment with additional tools to improve the assessment.

Before a risk assessment is performed it is advised to perform a screening to identify potential hazards that will be included in the assessment. After the most relevant hazards have been identified, the suitable assessment tools (category I and II) can thereafter be chosen. Examples of broad screening tools targeting WMSDs include:

• Basis-Check (BAUA - The Federal Institute for Occupational Safety and Health, Germany, in German only, interactive pdf^[3])
• Checklist Physical load (TNO, Netherlands, online tool^[4])
• RAMP I (KTH Royal Institute of Technology, Sweden, pdf and as Excel-format^[5])
• Risk Assessment Worksheets (Health and Safety Executive, UK, pdf^[6])

Structure of this document

The assessment tools in this document have been divided in two categories.

• Category I include tools that have been assessed as quick and easy to use, but may lack a high level of detail, and may or not have been (yet) published in the peer-reviewed scientific literature.
• Category II include tools that provide a higher level of detail and have been published in the peer-reviewed scientific literature.

Additionally, an overview of relevant ergonomics standards is also provided. These can also be used for assessment of WMSDs.

Category I tools

The Key Indicator Methods (KIM)

The Federal Institute for Occupational Safety and Health (BAUA) in Germany has developed the revised Key Indicator Methods (KIM) including six tools for assessment of various biomechanical loads^[7].

The tools are available in English, Dutch, French, German Italian, Spanish, Swedish and Turkish.

The revised KIM tool are based on the original KIM tools developed to be quick and easy to use by managers and safety representatives. So far, the revised Key Indicator Methods have not yet been published in the peer-review scientific journal articles – nor have their ‘risk levels’ been validated in either cross-sectional, nor in longitudinal studies – so caution needs to be applied when interpreting these results.

Table 1. Examples of ‘category I’–tools developed by BAUA targeting manual handling, work postures and upper limb movements.

Other KIM tools: KIM-BM (Body-Movement)

The Health and Safety Executive (HSE) tools^[8]

MAC^[9], RAPP^[10] and ART^[11] tool have been developed by the Health and Safety Executive in the UK to support health and safety Inspectors. Both MAC and RAPP are based on the Liberty Mutual guidelines. MAC targets lifting and carrying tasks and RAPP targets pushing and pulling tasks. The ART tool targets repetitive movements of the upper limbs. So far these tools have not yet been published in the peer-review scientific journal articles – nor have their ‘risk levels’ been validated in either cross-sectional, nor in longitudinal studies, so caution needs to be applied when interpreting their results.

Table 2. Examples of ‘category I’–tools developed by HSE targeting manual handling, work postures and upper limb movements.

Category II tools

The revised NIOSH Lifting Equation^[12]

The revised NIOSH Lifting Equation^[13] was developed by the National Institute for Occupational Safety and Health (NIOSH) in the US and was released 1991. It is considered as the state-of-art tool for assessing lifting and lowering tasks and is incorporated in both the European ergonomics standard (CEN 1005–2) and the global ergonomics standard (ISO 11228-1). The tool has been extensively validated for prediction of lifting-related low back pain^[14]. NIOSH has developed a mobile application, NLE Calc^[15] to calculate the overall risk index for single and multiple manual lifting tasks. Checklists of the tool are also provided in the both standards (i.e. CEN 1005–2 and ISO 11228-1) were also team handling can be assessed.

The RAMP II tool^[16]

The RAMP II tool has been developed by KTH Royal Institute of Technology in Sweden and was first released 2014^[17]. The tool covers a broad range of risk factors and has incorporated a simplified version of the revised NIOSH Lifting Equation for quick assessment of lifting task, but with extension of factors including e.g., team handling. For pushing and pulling, the tool has incorporated a simplified version of the Liberty Mutual guidelines / ISO 11228-2 but with additional task parameters. The tool has been published in the peer-review scientific literature^[18] but has not yet been tested for its predictive validity, hence caution needs to be applied when interpreting its ‘risk levels’. The tool includes a system for generating risk reducing measures and extensive free online training package. Checklists of the tool are available in English and in Swedish in pdf- and in Excel-format (link)^[16].

‘HAL TLV’ – the ACGIH Hand Activity Level (HAL) Threshold Limit Value (TLV)

The tool can be used for assessment of repetitive movements and forceful exertions of the hand. It focus on the movement pattern of the hand/arm and the relative exertion level. The tool has been validated for prediction of e.g., carpal tunnel syndrome in several longitudinal studies. The tool was revised in 2018^[19]. The tool is limited to the hand and arm and does not include other parts of the body such as the back and neck.

The Revised Strain Index (RSI/SI)

In conformity with ‘HAL TLV’, the Strain Index targets assessment of repetitive movements and forceful exertions of the hand. The Strain Index was revised in 2017^[20] and includes task parameters such as the duration per workday and per exertion, frequency of exertion, exertion magnitude and wrist posture. The tool has been validated for prediction of e.g., carpal tunnel syndrome in several longitudinal studies. The tool is limited to the hand and arm and does not include other parts of the body such as the back and neck.

OCRA

OCRA mainly focus on the assessment of repetitive work involving the upper limbs^[21]. The tool is available as a screening tool (Method 1 in ISO 11228-3) and as a more in-depth assessment tool (Method 2 in ISO 11228-3).

HARM^[22]

Hand Arm Risk assessment Method (HARM) has been developed by TNO in the Netherlands for assessment of repetitive work involving the upper limbs^[23]. HARM has been validated in a retrospective study^[24]. The tool is limited to the upper limbs and do not include other parts of the body such as the back.

DUET^[25]

The Distal Upper Extremity Tool (DUET) targets assessment of repetitive and forceful exertions of the upper limbs. For assessment, the tool combines subjective assessed exertion level and frequency of the exertion. DUET has been validated for musculoskeletal pain and/or injury using cross-sectional data^[26].

Table 3. Examples of ‘category II’–tools targeting manual handling, work postures and upper limb movements.

Category II tools – European and global ergonomics standards

In addition to the previously mentioned Category II tools, both the European and global ergonomics standards can be used for assessment of manual handling, constrained postures and repetitive work (involving the upper limb) (Table 4).

Table 4. European and global ergonomics standards targeting manual handling, work postures and upper limb movements.

Tools for person/patient transfer

A number assessment tools have been developed specifically targeting assessment of person/patient transfer such as the PTAI (Patient Transfer Assessment Instrument), the Care Thermometer (TilThermometer^[27]) and the MAPO method (Movement and Assistance of Hospital Patient).

In addition to these, other tools such as the revised NIOSH lifting equation (and hence, EN 1005-1, 11228-1, and RAMP II) can be used under certain circumstances – such as if a) the care recipients can follow instructions and is not combative, and if b) the specific weight that the caregiver handles manually can be estimated.

The technical report from ISO (ISO/TR 12296:2012 Ergonomics — Manual handling of people in the healthcare sector^[28]) provides guidance for selecting tools when assessing manual handling of people in the healthcare sector and Villarroya et al.^[29] provide a comparison of tools for assessment of person/patient transfer.