脑脊液Aβ-42与tau浓度比值预测老年患者发生术后认知功能障碍的准确性

Accuracy of cerebrospinal fluid Aβ-42 to tau level ratio in predicting postoperative cognitive dysfunction in elderly patients

目的 评价脑脊液β淀粉样蛋白42与tau浓度比值（Aβ-42/tau）预测老年患者发生术后认知功能障碍（POCD）的准确性.方法 拟在脊椎-硬膜外联合麻醉下行全髋或膝关节置换术患者80例,性别不限,年龄65 ～ 85岁,ASA分级Ⅱ或Ⅲ级,经L34间隙穿刺,蛛网膜下腔穿刺成功后取2 ml脑脊液,检测Aβ-42和tau的浓度（单位为pg/ml）,计算二者比值.于术前1 d和术后7d进行神经心理学测验,采用Z计分法确定POCD,根据是否发生POCD,分为非POCD组和POCD组.利用ROC曲线确定区分POCD患者与非POCD患者的截断值.结果 32例患者发生了POCD,发生率为40％,非POCD组和POCD组脑脊液Aβ-42/tau分别为2.6±0.3、1.7±0.4,POCD组低于非POCD组（P＜0.01）.以脑脊液Aβ-42/tau预测发生POCD的灵敏度为91.7％,特异度为81.2％,约登指数为0.7.ROC曲线区分POCD患者与非POCD患者脑脊液Aβ-42/tau的截断值为2.0.结论 脑脊液Aβ-42/tau可准确地预测老年患者POCD发生.

Objective To evaluate the accuracy of cerebrospinal fluid （CSF） amyloid beta 42 （Aβ-42） to tau level ratio （Aβ-42/tau） in predicting postoperative cognitive dysfunction （POCD） in elderly patients.Methods Eighty ASA physical status Ⅱ or Ⅲ patients of both sexes,aged 65-85 yr,undergoing elective total hip or knee replacement under combined spinal-epidural anesthesia,were enrolled in the study.Epidural catheter was placed at T3,4 interspace,and after a catheter was successfully placed into the subarachnoid space,CSF 2 ml was obtained to measure Aβ-42 and tau levels （units：pg/ml）,and the ratio between them was calculated.Neuropsychological tests were performed at 1 day before surgery and 1 week after surgery.The Z score was used to identity POCD.The cut-off value for POCD and nonPOCD patients was determined by using ROC curve.Results Thirty-two patients were diagnosed with POCD,and the incidence was 40％.The Aβ-42/tau was 2.6±0.3 and 1.7±0.4 in non-POCD and POCD groups,respectively,and the ratio was significantly lower in POCD group than in non-POCD group.The sensitivity of CSF Aβ-42/tau in predicting POCD was 91.7％,the specificity was 81.2％,and Youden index was 0.7.ROC curves revealed that the cut-off value for POCD and non-POCD patients was 2.0.Conclusion CSF Aβ-42/tau can accurately predict the occurrence of POCD in elderly patients.