CMIA法检测老年人群梅毒螺旋体抗体的假阳性分析

An analysis of false-positive results of chemiluminescence microparticle immunoassay in detecting Treponema pallidum antibodies in the elderly population

目的:分析化学发光微粒子免疫分析法(chemiluminescence microparticle immunoassay,CMIA)在老年人群梅毒螺旋体(TP)感染筛查检测中的假阳性率,并分析原因及提出处理措施。方法:将医院门诊和住院部2017年11月至2018年12月需要进行TP抗体筛查的患者分为观察组(年龄≥60岁)和对照组(年龄18～59岁),通过CMIA法进行筛查检测,S/CO值>1的样本采用TPHA(Treponema pallidum hemagglutination assay)法确诊。结果:108 345例患者血清标本共筛查出阳性样本4 442例,经TPHA试验确诊为阳性共4 169例。观察组CMIA法检测出的阳性率为8.15%,而假阳性率为0.76%,较对照组(阳性率为3.43%,假阳性率为0.04%)明显升高,差距有统计学意义(P <0.05)。观察组假阳性率男性高于女性(P <0.05)。结论:老年人群基础疾病多,干扰因素复杂,CMIA法检测TP抗体时易出现假阳性,在CMIA法低值阳性结果时应采用多种方法复检,并结合临床资料及确诊试验结果综合判断。

Objective: To analyze the false-positive rate of chemiluminescence microparticle immunoassay (CMIA) in screening for Treponema pallidum (TP) antibodies in the elderly population, and to investigate the likely causes and propose solutions. Methods: The outpatients and inpatients who needed TP antibody screening from November 2017 to December 2018 were divided into observation group (age ≥60 years) and control group (age 18 ~ 59 years). CMIA was performed as a screening test. Treponema pallidum hemagglutination assay (TPHA) was then per? formed as a confirmatory test in patients with S/CO score >1. Results: 4 442 positive samples were detected by CMIA from the total 108 345 samples, of which 4 169 positive samples were confirmed by TPHA. The positive rate determined by CMIA in the observation group was 8.15%, with a false-positive rate of 0.76%, significantly higher than those in the control group (positive rate: 3.43%;false-positive rate: 0.04%)(P < 0.05). The false-positive rate in the observation group was significantly higher in males than in females (P < 0.05). Conclusion: CMIA tends to yield a high false-positive rate for detecting TP antibodies in the elderly population due to many underlying diseases and interfering factors. When positive samples detected by CMIA have a relatively low S/CO score, multiple confirmatory tests should be performed, and the final diagnosis of syphilis should be made with reference to clinical data and results from confirmatory tests.