Determination of the optimal cutoff values for pain sensitivity questionnaire scores and the oswestry disability index for favorable surgical outcomes in subjects with lumbar spinal stenosis

Abstract

Study Design. Retrospective analysis of prospectively collected data (NCT02134821). Objective. The aim of this study was to elucidate the cutoff values for signifi cant predictors for favorable outcomes after lumbar spine surgery in patients with lumbar spinal stenosis (LSS). Summary of Background Data. Various factors are associated with the surgical outcomes for patients with LSS. However, we did not know the odds ratio and/or cutoff values of a predictive factor for a favorable surgical outcome for LSS. Methods. A total of 157 patients who underwent spine surgery due to LSS between June 2012 and April 2013 were included in this study. The patients were dichotomized into 2 groups on the basis of an Oswestry Disability Index (ODI) score of 22 or less (favorable outcome group) or more than 22 (unfavorable outcome group) at 12 months after surgery. Regarding favorable outcomes, the odds ratio for each preoperative variable including demographic data, preoperative symptom severity, and pain sensitivity questionnaire (PSQ) score was calculated using univariate and multivariate logistic regression analyses. For the signifi cant variables for surgical outcome, receiver operating characteristic (ROC) curve was plotted with calculation of the area under the ROC curve. Results. Multivariate analysis revealed that the ODI and total PSQ scores were signifi cantly associated with a greater likelihood of an unfavorable surgical outcome [odds ratio (95% confi dence interval) of ODI, 1.289 (1.028–1.616); odds ratio (95% confi dence interval) of total PSQ, 1.060 (1.009–1.113)]. ROC analysis revealed area under the ROC curves for the total PSQ and ODI scores of 0.638 ( P = 0.005) and 0.692 ( P < 0.001), respectively. Conclusion. Preoperative disability and pain sensitivity can be predictors of the functional level achieved after spine surgery in patients with LSS, and the ideal cutoff values for the total PSQ and ODI scores were 6.6 and 45.0, respectively.