THE NORTH-AMERICAN SPINE SOCIETY LUMBAR SPINE OUTCOME ASSESSMENT INSTRUMENT - RELIABILITY AND VALIDITY TESTS

Study Design. A cross-sectional study of a convenience sample of lumba r spine patients, with a subsample followed for retest reliability. Ob jectives. To assess the instrument's reliability, validity, and accept ability to patients. Summary of Background Data. Patients with eight d iagnoses, four before surgery and four after surgery, were recruited f rom six orthopedic practices to test the questionnaire. Methods. One h undred sixty-seven patients were approached through the physician's of fice, yielding 136 usable questionnaires (84%) and 24-hour retests on 64 patients. Results. The questionnaire took about 20 minutes to admin ister and was acceptable to patients. The lumbar spine pain and disabi lity and neurogenic symptoms subscales discriminated among patient gro ups as hypothesized and showed significantly better scores for patient s independently judged successful by their physicians after surgery. T est-retest reliability and internal reliability were high (range, 0.85 -0.97). Sample sizes of 20-37 would be needed to detect a 20% differen ce between two groups (alpha, 0.05; beta, 0.20). Conclusions. The ques tionnaire should be considered for monitoring of individual patient's progress in treatment and for clinical trials.