Performance of health-status scales when used selectively or within multi-scale questionnaire

Two groups of patients referred to an orthopedic department completed a mailed questionnaire within 4 weeks prior to and a second questionnaire during their visit. The first group completed three SF-36 scales related to physical health (physical functioning, bodily pain, and general health perceptions) on one occasion and all eight SF-36 scales on the other occasion. The second group completed the entire SF-36 on two occasions. Results for patients who reported unchanged health status and had complete scores were analyzed; 80 patients in the first and 62 patients in the second group.The Cronbach alpha reliability and intraclass correlation coefficients exceeded 0.7 for all three scales for both groups. For the first group the mean difference between the scores was 0.4 point for physical functioning, 2.5 points for bodily pain, and 0.5 point for general health perceptions, which did not differ significantly from the corresponding differences for the second group (0.1, 1.9 and 1 point, respectively).The use of selected scales from a multi-scale health-status questionnaire seems to yield similar results compared to their use within the entire questionnaire.Measures of health status and quality of life are being increasingly used in clinical research. In the evaluation of many conditions, it might be necessary to combine generic and disease-specific questionnaires. Many questionnaires are long and consist of several scales, which might substantially increase responder burden. Generic health-status questionnaires usually consist of separate scales related to physical and mental health. In musculoskeletal conditions, physical health scales are more likely to show differences after treatments and would thus be used in sample size estimations; mental health scales would then lack the power to show differences. It has been suggested that multi-scale health-status questionnaires should be used in their entirety and that the use of selected scales would, by taking them out of