Sources of variation in work disability assessment.

The assessment of work disability due to health problems is a difficult task because there is no straightforward relationship between disease and disability. As a result, there is wide inter-rater variability between physicians in assessing work disability. The aim of this paper is to discuss the sources of the inter-rater variability and to describe possibilities for its reduction. A model is presented in which the process of disability assessment, the instruments used and the role of the assessor is addressed. On the basis of this model, the causes of inter-rater variability and suggestions for improvement are discussed.