title: A comparison of two time intervals for test-retest reliability of health status instruments.
abstract: Studies of test-retest reliability for health-related quality of life instruments have used varying intervals between test administrations. There is no evidence available to aid in the selection of the time interval between questionnaire administrations for a study of test-retest reliability for health status instruments. We compared the test-retest reliability at 2 days and 2 weeks for four knee-rating scales and the eight domains of the SF-36. Seventy patients with disorders of the knee who were in a stable state were randomly allocated to repeat the questionnaires at either 2 days or 2 weeks. There were no statistically significant differences in the test-retest reliability (intraclass correlation coefficient and limits of agreement statistics) for the two time intervals.
authors.affiliation: Sports Medicine and Shoulder Service Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA. marxr@hss.edu
authors.forename: Robert G
authors.initials: RG
authors.lastname: Marx
authors.forename: Alia
authors.initials: A
authors.lastname: Menezes
authors.forename: Lois
authors.initials: L
authors.lastname: Horovitz
authors.forename: Edward C
authors.initials: EC
authors.lastname: Jones
authors.forename: Russell F
authors.initials: RF
authors.lastname: Warren
mesh_terms: D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000503:physiopathology; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018401:Sample Size; D011795:Surveys and Questionnaires; D013997:Time Factors