Comparing four tools to measure disability at work

In Brief

  • Measuring productivity losses due to disability experienced at work (presenteeism) more fully accounts for the impact of work-related injuries.
  • Four tools used to assess productivity losses were compared. Each showed some evidence of reliability and validity for measuring at-work disability among injured workers with shoulder or elbow disorders. No single tool was clearly superior to the others.

Why was this study done?

This study compares four tools that measure the extent of on-the-job disability among workers with shoulder or elbow disorders. Absenteeism is the traditional measure of productivity losses associated with workplace injuries. However, there is a growing recognition that losses due to at-work disability should also be measured. This will more fully reveal the impact of such injuries — and the resulting need for effective health-care and prevention programs. Yet little information is available on which tools are best for this purpose.

How was the study done?

Researchers recruited 80 injured workers attending a shoulder and elbow specialty clinic funded by the Ontario Workplace Safety and Insurance Board. Workers filled out four different questionnaires that measure at-work disability. The measures included:

  • a four-item work module of the Disabilities of the Arm, Shoulder and Hand Outcome Measure (DASH-Work)
  • a 16-item Work Limitations Questionnaire (WLQ-16)
  • a 23-item Work Instability Scale for Rheumatoid Arthritis (RA-WIS)
  • a six-item Stanford Presenteeism Scale (SPS-6).

The workers were also asked about their ability to work and their productivity. This allowed researchers to assess how well the tools measured disability on the job. As well, workers were asked for their opinions on each tool.

What did the researchers find?

No single tool clearly emerged as being superior to the others. All tools showed some evidence that they were reliable and valid in measuring at-work disability among workers with elbow and shoulder disorders. However, workers’ self-reports of work ability and productivity on the job did not correlate with the tools as well as expected. The researchers suggest that there is still room for improvement in measuring at-work disability. In the end, the WLQ-16 was considered the most versatile instrument for this population because it looked at work disability from a number of different perspectives. The SPS-6 was considered the poorest performer of the four scales. Workers strongly preferred the RA-WIS over the other tools.

What are some strengths and weaknesses of the study?

Researchers were able to directly compare four different measures in injured workers with similar musculoskeletal disorders. However, the degree to which these results apply to other conditions or more acute injuries is unknown.

Publication Information

Title: 

Comparison of the psychometric properties of four at-work disability measures in workers with shoulder or elbow disorders

Author(s): 

Tang K, Pitts S, Solway S, Beaton D

Journal: 

Journal of Occupational Rehabilitation, 2009: vol. 19, no. 2, pp. 142-154