Metrics
Selecting an At-work Shoulder or Elbow Disability Measure
Tang K, Pitts S, Solway S, Beaton D. Comparison of the psychometric properties of four at-work disability measures in workers with shoulder or elbow disorders. J Occup Rehabil. 2009; 19:142-154.
Abstract
Introduction: To better capture the extent of work disability following an occupational injury, clinical researchers are beginning to recognize the importance of considering not only levels of absenteeism, but also disabilities experienced while “at work.” Although at-work disability measures are available in the literature, currently there is little insight on the selection of specific measures that may be best suited for a given population or situation. The objectives of this study are to assess and compare the measurement properties of four self-report at-work disability measures in workers with shoulder or elbow disorders.
Methods: Study sample consisted of 80 patients attending a shoulder and elbow specialty clinic operated by the Worker Safety Insurance Board of Ontario. Internal consistency reliability, validity, and patient preference of four at-work disability measures were compared in a cross-sectional design. Selected measures included the work module of the Disabilities of the Arm, Shoulder, and Hand Outcome Measure; Work Limitations Questionnaire (WLQ-16); Work Instability Scale for Rheumatoid Arthritis (RA-WIS); and Stanford Presenteeism Scale.
Results: All four measures demonstrated evidence of internal consistency, reliability (alpha=0.76–0.90), and construct validity, although only modest correlations against work-oriented constructs (r=0.37–0.60) were observed. The RA-WIS was most preferred by respondents (44.6%) over the other measures.
Conclusions: Although no single scale stood out as clearly superior, the WLQ-16 was considered the best overall performer. Variable performance between the scales suggests some divergence in the way these measures conceptualize “at-work disability,” which may be important to consider when selected instruments for future studies.
An issue that needs to be addressed is whether the types of jobs differ for persons with different diagnoses. When the WLQ was used with patients with RA, they could not answer a number of questions.
Commentary
Disability related to arthritis represents a major personal and economic issue for the individual and society. For the individual, the effects of pain and limited mobility affect the quality of life. More broadly, arthritis affects society through the loss of productivity. The Centers for Disease Control (CDC) report that about one in 20 U.S. adults between the ages of 18 and 64 years have work limitations due to arthritis.1
In a previous study supported by the CDC, Theis et al used 2002 data available from the National Health Interview Survey (NHIS), to estimate the national prevalence of arthritis-attributable work limitation (AAWL) among persons between the ages of 18 and 64 years who had doctor-diagnosed arthritis. Persons were asked whether their condition affected whether they worked, the type of work they did, and the amount of work they did. Almost 30% of the 23.4 million (approximately 6.9 million) in this group reported AAWL. The site of joint pain did not seem to be a contributing factor.2