Effect of apolipoprotein E genotype on the outcome after anterior cervical decompression and fusion in patients with cervical spondylotic myelopathy

Abstract

Object The authors examined a possible association between apolipoprotein E (APOE) gene polymorphism and the outcome after anterior microsurgical decompression in patients with cervical spondylotic myelopathy (CSM). Methods The authors conducted a prospective study of 60 consecutive patients (40 men, 20 women) with CSM who underwent anterior microsurgical decompression. The patients ranged in age from 26 to 86 years (mean 61.5 ± 14.6 years). Neurological deficits were classified according to the modified Japanese Orthopaedic Association Scale. Mean follow-up was 18.8 ± 4.6 months and APOE genotyping was carried out by isolation of DNA from venous blood samples. The APOE genotypes were determined by polymerase chain reaction followed by restriction enzyme digestion and polyacrylamide gel electrophoresis of digested fragments. Categorical variables were analyzed with the chi-square test, continuous data with the Mann-Whitney U-test, and for multiple groups with the Kruskal-Wallis H-test. A backward stepwise binary logistic regression analysis was performed to determine the effect of APOE in a multivariate model. Results Of the 60 patients with CSM, 35 (58.3%) improved and 25 (41.7%) did not improve or suffered deterioration (no-improvement group). In the improvement group 5 patients (8.3%) possessed the ε4 allele compared with 16 patients (26.7%) in the no-improvement group (p = 0.002, OR 3.3, 95% CI 1.7–6.1). In a multivariate model, the occurrence of the ε4 allele was a significant independent predictor for no improvement after anterior decompression and fusion (p = 0.004, OR 8.6, 95% CI 5.1–20.6). Conclusions The results of this study show that APOE gene polymorphism influences the short-term outcome of CSM patients after surgical decompressive and stabilizing therapy in the way that the presence of the APOE ε4 allele is an independent predictor for a no improvement. The presence of APOE may explain in part the different responses to operative therapies in patients with cervical myelopathy.