title: Performance of health-status scales when used selectively or within multi-scale questionnaire.
abstract: BACKGROUND
  Little work has been done to investigate the suggestion that the use of selected scales from a multi-scale health-status questionnaire would compromise reliability and validity. The aim of this study was to compare the performance of three scales selected from the SF-36 generic health questionnaire when administered in isolation or within the entire SF-36 to patients with musculoskeletal disorders.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Physical Therapy, Lund University, Sweden. christina.gummesson@sjukgym.lu.se
authors.forename: Christina
authors.initials: C
authors.lastname: Gummesson
authors.forename: Isam
authors.initials: I
authors.lastname: Atroshi
authors.forename: Charlotte
authors.initials: C
authors.lastname: Ekdahl
mesh_terms: D006304:Health Status; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires