Construct validity and responsiveness of commonly used patient reported outcome instruments in decompression for lumbar spinal stenosis.

Abstract

Background\nValidity and responsiveness of Oswestry disability index (ODI), Roland Morris disability questionnaires (RMDQ), Short Form-12 Physical Component Score (SF-12 PCS) and Short Form-12 Mental Component Score (SF-12 MCS) in patients undergoing open decompression for lumbar canal stenosis has not been previously reported.\n\n\nMethods\nOutcome assessment was prospectively evaluated using the ODI, RMDQ, SF-12 PCS and SF-12 MCS pre-intervention and at average follow-up of three months post-intervention. Pearson correlation coefficient was used to evaluate the association between change in values of ODI, RMDQ, SF-12 PCS and SF-12 MCS. Distribution based methods (Effect size [ES], standardised response mean [SRM]) and anchor based method (Area under the curve [AUC] of receiver operating curve [ROC]) were used to determine responsiveness. AUC value\xa0≥\xa00.70 is considered as adequate level of responsiveness and the outcome instrument with the largest AUC is considered to be the most responsive outcome instrument.\n\n\nResults\nThis study included 77 participants. Responsiveness was assessed at a mean follow-up of 12 weeks postoperatively. There was significant strong correlation between ODI and RMDQ (r\xa0=\xa00.65, p\xa0<\xa00.0001). The ES of ODI, RMDQ, SF-12 PCS and SF-12 MCS were 1.54, 1.48, 1.85 and 0.51 respectively. The SRM of RMDQ, ODI, SF-12 PCS and SF-12 MCS were 1.22, 1.17, 1.0 and 0.47 respectively. AUC of ODI, RMDQ, SF-12 PCS and SF-12 MCS were 0.83-0.88, 0.82 to 0.86, 0.78 to 0.81 and 0.69 to 0.70 respectively.\n\n\nConclusion\nIt is recommended to use either ODI or RMDQ as region specific patient reported outcome instrument and SF-12 PCS as a health related quality of life outcome instrument to evaluate outcome after decompressive laminectomy for lumbar canal stenosis.