Functional status and disability questionnaires: What do they assess? A systematic review of back-specific outcome questionnaires

Study Design. A systematic literature review of outcome questionnaires designed for assessing functional status or disability in patients with low back pain. Objectives. To provide a comprehensive overview of all functioning/disability questionnaires used in recent years and to explore how the main concept(s) was described or defined in the original paper, the content or the domains of disability, and the measurement properties of the questionnaires. Summary of Background Data. A number of clinical tools designed for evaluating the functional status of patients with low back pain have been developed. Only a few have been reviewed earlier, and there has been little focus on the content reflected in the questionnaires. Methods. Papers including questionnaires for assessing disability, function, activity limitations, or participation restrictions in adult patients with low back pain were searched in the MEDLINE and CINAHL databases for the period from January 1996 to January 2002. Two independent and blinded researchers read and selected abstracts and questionnaires. The content of the included questionnaires was classified according to World Health Organization's International Classification of Functioning, Disability and Health. The measurement properties were analyzed according to recommended guidelines. Results. A total of 36 back-specific questionnaires were identified. When distinguishing among a bodily, personal, and social perspective of functioning, 4 main types of content were identified. Most of the outcome questionnaires had a mixed content reflecting various constructs such as pain and symptoms, sleep disturbances, psychological dysfunctions, physical impairments, and social functions. Nine questionnaires assessed solely activities of daily living. For one-third of the questionnaires, the measurement properties were reported in only the original study. Conclusions. Although most questionnaires had their main focus on activity limitations, a considerable variation with respect to the main concept and content was found. Only a few of the questionnaires can be considered acceptably validated.