Objectives: The objective of this study was to compare the content covered by the North American Spine Society Lumbar Spine Outcome Assessment Instrument, the Oswestry Low Back Disability Questionnaire, and the Roland-Morris Disability Questionnaire based on the International Classification of Functioning, Disability and Health (ICF).
Methods: The linkage of items of the three measures to the ICF involved three steps, which were performed by two different health professionals and in which 10 different linking rules were applied.
Results: In the 48 items of the three instruments, a total of 123 concepts were identified and linked to the ICF. The concepts contained in the items were linked to 10 ICF categories of the component "body functions," 27 of the component "activities and participation," and 4 of the component "environmental factors." The estimated kappa coefficients ranged from 0.67 to 1.00.
Conclusion: Comparison based on the ICF provides insight into both the breadth of health dimensions measured as well as the thoroughness and depth of measurement. Therefore, it can be a useful tool when selecting specific measures for a study. Compared with other types of qualitative review, the most important advantage of the content comparison of measures based on the ICF is the use of an external and independent reference to which all the instruments can be linked and by which all the instruments can be compared. The three back-specific measures are comparable, with their common focus on physical aspects of body functions and activities and participation.