Validity of Nordic-style questionnaires in the surveillance of upper-limb work-related musculoskeletal disorders

Objectives: The study aimed at comparing results of standardized Nordic-style questionnaires with those of clinical examinations in two surveys on upper-limb work-related musculoskeletal disorders. Methods: The "repetitive task" survey (1757 workers in 1993-1994 and 598 workers in 1996-1997) studied risk factors of the disorders among those exposed to repetitive work. The "Pays de la Loire" survey (2685 workers in 2002-2003) was part of a population-wide surveillance system. In both surveys, each worker completed a Nordic-style questionnaire and underwent a standardized clinical examination. The presence of at least one upper-limb work-related musculoskeletal disorder was compared, with an evaluation of sensitivity, specificity, and kappa values, with a clinical examination as reference. In the second survey, a global score of a numerical scale for the severity of symptoms at the time of the examination was evaluated in the same way (plus ROC curves). Results: Agreement between the questionnaire and the examination differed in the two surveys, from kappa 0.22 [95% confidence interval (95% CI) 0.19-0.23] in the "Pays de la Loire" survey to kappa 0.77 (95% CI 0.74-0.80) in the "repetitive task" survey in 1993-1994. Overall, sensitivity was excellent (82.3-100%). The specificity varied, from 51.1% in the "Pays de la Loire" survey to 82.4% for the ≥2 score based on the severity of symptoms in the survey. Conclusions: Nordic-style questionnaires exploring symptoms in the past year can be useful tools for monitoring upper-limb work-related musculoskeletal disorders, especially if they include numerical rating scales of symptom severity. Physical examination remains essential for a medical or clinical diagnosis.