Risk factors for poor outcome of surgery for cervical spondylotic myelopathy.

STUDY DESIGN: Prospective study. OBJECTIVES: The purpose of this study was to characterise risk factors for poor surgical outcome in patients with cervical spondylotic myelopathy (CSM). METHODS: The prospective study included 110 consecutive patients who underwent surgical treatment for CSM. Surgical outcomes were evaluated according to the Japanese Orthopaedic Association (JOA) score. JOA recovery rate <50% was defined as poor surgical outcome. Relationship between outcome and various clinical and imaging predictors was examined. By multivariate logistic regression analysis, we identified risk factors associated with poor outcome. Receiver operating characteristic curves were plotted to acquire cutoff values for the continuous variables found to be independently associated with poor outcome. RESULTS: Forty-two patients (38.2%) had a recovery rate of <50%. Logistic regression, with poor outcome as dependent variable, showed independent risks associated with increased age (odds ratio (ORs)=1.08, 95% confidence interval (CI)=1.01-1.15, P=0.021), symptom duration (OR=4.01, 95% CI=1.95-8.23, P=0.000) and signal intensity ratio (SIR, OR=4.24, 95% CI=1.61-11.20, P=0.003). The cutoffs with the best compromise between sensitivity and specificity were set at 63.1 years of age, 9 months of symptom duration and 1.455 for SIR. The presence of ⩾2 out of three factors (age ⩾63.1 years, symptom duration ⩾9 months and SIR ⩾1.455) gave an overall OR of 33.15 (95% CI=4.11-267.37, P=0.001). CONCLUSION: These findings suggest that advanced age, long-term CSM symptoms and high preoperative SIR are risk factors for poor outcome of surgery in patients with CSM.