CLINICAL OVERALL SCORE - OUTCOME EVALUATION AFTER LUMBAR DISC SURGERY, ASSESSMENTS OF RELIABILITY AND VALIDITY

In previous studies assessing prognostic factors for the outcome of lu mbar disc surgery, a Clinical Overall Score (COS) based on four subset s-pain intensity (VAS), physical signs, functional status (Oswestry) a nd analgesics-was used as the main outcome criterion. Both the patient 's and the examiner's opinions of outcome and return to work were regi stered. In this paper, assessments are made of reliability and validit y regarding the COS. The COS was found sensitive to changes, and inter nal consistency, assessed using Cronbach's alpha, Pearson's correlatio n analyses and factor analysis, was good. An interrater reliability st udy of the assessments of the physical signs, using weighted Kappa sta tistics, demonstrated fair to good levels of agreement for most of the signs. The concurrent validity of the COS was satisfactory; COS compa red favourably with the patient's and with the examiner's opinion of o utcome and return to work.