Reading Rheum

This current study by Tang et al makes a distinction between two work-related disability concepts: “absenteeism” due to disability and “at-work disability.” The authors make a case for measuring the difficulties that persons experience at work, focusing on more than just absenteeism. They believe that using complementary measures of the two concepts is important “for quantifying the impact of work-related injuries, for estimating the associated economic burden, and for evaluating the potential value and effectiveness of healthcare interventions or prevention strategies aimed at reducing this burden.”³

Four measures were selected for comparison of their psychometric properties, as well as of respondents’ preference. These measures included the following: 1) Work module of the Disabilities of the Arm, Shoulder and Hand Outcome Measure (DASH-W); 2) WLQ-16; 3) RA-WIS; and 4) Stanford Presenteeism Scale (SPS-6). The study sample was composed of 80 persons who were attending a treatment clinic for shoulder or elbow injuries. Workers referred to this clinic are typically those who experience poor recovery after their initial treatment, which may include surgery. There is no mention of the sample number who might have had an arthritis diagnosis. The average age of the sample was 43 years; 34 (42.5%) were female and 43 (53.8%) were male.

Even though the effects on work may be similar among different diagnoses, this point should be taken into consideration when looking at the study results that showed that the WLQ-16 was the “best performer” and the RA-WIS was the “most preferred.”³ Interestingly, these two measures (i.e., WLQ and RA-WIS) were reviewed in a special 2003 issue of Arthritis Care & Research that focused on measures of patient outcomes in rheumatology.⁴ Both have also been discussed as measures of productivity for persons with rheumatoid arthritis (RA).⁵

Information related to the content of these four instruments is helpful when looking at their potential use for persons with arthritis as well as understanding the study results. Below is a short description of each. All have demonstrated adequate reliability and validity prior to this study.

1. DASH-W: The DASH was designed “to measure physical function and symptoms in people with any of several musculoskeletal disorders of the upper limb.”⁶ The Work Module includes four items assessing difficulty in work performance in the past week.
2. WLQ-16: The WLQ measures “the degree to which chronic health problems interfere with the ability to perform job roles.”⁷ This measure includes 16 items, and responses are based on two-week recall. Four domains have been identified: time management, physical demands, mental–interpersonal, and output demands.
3. RA-WIS: The RA-WIS measures work instability, or the “mismatch between functional incapacity and work demands at a point in time.”⁸ It has 23 binary response (yes/no) items, with one’s response based on current perception.
4. SPS-6: The SPS-6 “assesses the relationship between presenteeism, health problems, and productivity of working populations” where “presenteeism” refers to the level of job performance due to a health problem.⁹ The initial tool of 36 items was reduced to six, and respondents are asked to rate their level of agreement with statements related to their work experiences over the past month.

Reliability, or internal consistency, was estimated for each of the four measures with this sample. All, except the RA-WIS, were analyzed using Cronbach’s coefficient alpha, appropriate for items rated on a Likert-type scale. The RA-WIS used the Kuder-Richardson technique (KR-20), appropriate for the dichotomous responses of “yes” or “no.” The reliability results ranged from .76 for the SPS-6 (six-item version) to .90 for the WLQ-16 (16 items).