Predictors of poor outcomes after posterior decompression surgery in patients with degenerative cervical myelopathy

Study Design: Retrospective multicenter study. Objectives: To identify predictors associated with failure of neurological improvement after posterior decompression surgery for degenerative cervical myelopathy (DCM). Setting: 17 institutions in Japan. Methods: Patients who underwent posterior decompression surgery and were followed up for >1 year were enrolled. The Japanese Orthopedic Association (JOA) recovery rate was determined, and patients were divided into three outcome groups based on the JOA recovery rate: fair (recovery rate, <22.2%: mean-1SD), moderate (22.3%–77.1%), and good (>77.2%: mean+1 SD) groups. Demographic information, postoperative complications, and radiographic parameters were assessed, and predictors of poor outcomes were identified using the multinominal logistic regression analysis. Results: Of 868 patients enrolled, 140 (16.1%), 586 (67.5%), and 142 (16.3%) were assigned to the fair, moderate, and good groups, respectively, with mean JOA recovery rates of 6.2% ± 13.7%, 50.1% ± 15.0%, and 90.6% ± 8.3%. Although there were significant differences in the frequency of diabetes mellitus among the three groups in the univariate analysis (26.4% vs. 23.0% vs. 14.1%; p = 0.03), the multinominal regression analysis revealed that old age was a significant independent predictor of poor outcomes in the comparison between the fair and good groups (odds ratio [OR], 1.62; 95% confidence interval [CI], 1.27–2.07; p < 0.01). Old age was also significantly associated with failure of neurological improvement between the fair and moderate groups (OR, 1.35; 95% CI 1.15–1.59; p < 0.01). Conclusions: Old age may be an independent predictor of failure of neurological improvement after posterior decompression surgery in patients with DCM.