血清AFP临界值判断对肝癌诊断的影响

Influence of Cut-off Value of AFP on Diagnosis of Hepatic Cancer

为探讨血清AFP诊断肝癌的合理临界值,本研究收集肝癌患者35例、正常对照者35例。血清AFP检测采用电化学发光法和酶联免疫吸附法(ELISA)定量,结果用t检验和χ2检验进行统计学分析。2种方法检测血清AFP水平显著相关,相关系数为0.978,检测值无显著性差异,P>0.05。二者ROC曲线下面积分别为0.890、0.880,说明血清AFP水平对肝癌诊断价值较高。按照约登指数最大原则确定血清AFP电化学发光法诊断肝癌的临界值为3.25μg/L,其敏感度为74.3%,特异度为94.3%,准确度为84.3%;ELISA法诊断肝癌的临界值为1.118μg/L,其敏感度为62.9%,特异度为100%,准确度为81.4%。而以目前常规临界值20μg/L来分析,则电化学发光法检测AFP诊断肝癌的敏感度仅为45.7%,特异度100%,准确度72.9%;ELISA法敏感度48.6%,特异度100%,准确度74.3%。因此合理降低临界值可有效提高血清AFP水平对肝癌的诊断价值。

To analyze a reasonable cut-off value of serum AFP in hepatic cancer diagnosis,35 cases of hepatic cancer patients and 35 healthy people were chosen as the samples.Electrochemiluminescence immunoassay（ECLIA）and enzyme-1inked immunosorbent assay（ELISA）are used to collect serum samples and analyze AFP levels.SPSS 18.0software was used for statistical analysis.The correlation coefficient is 0.978,showing the results by ECLIA were significantly correlated to those by ELISA.They had no significant difference,P〉0.05.The area under the ROC curve was 0.890,0.880 respectively by these two methods.The sensitivity,specificity and accuracy were 74.3%,94.3%,84.3%by ECLIA if taking 3.25μg/L as cut-off value and 62.9%,100%,81.4%by ELISA if taking 1.118μg/L as cut-off value.Whereas if taking 20μg/L as cut-off value,the sensitivity and accuracy were only 45.7%,72.9%by ECLIA and 48.6%,74.3% by ELISA.So decreasing cut-off value of serum AFP can improve the diagnosis value of hepatic cancer effectively.