惊！POCT快速检测对沙眼衣原体的敏感性为零

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据一项在137名卢旺达妇女身上进行的研究结果显示，被称为BioChekSwab的快速沙眼衣原体检测试剂盒的敏感性为0%。

　　另据比利安特卫普时热带医学研究所 Irith De Baetselier 博士在给路透社健康的邮件中称“这种方法获得了CE标签，进而作为一种可用的方法在市场上销售，然而不幸的是，在我们这个小型的研究结果中发现该方法并未起作用。”

　　BioChekSwab 使用一种酶的底物，当被沙眼衣原体特异性肽水解酶水解，通过添加显色剂进而生成可用比色法读取的颜色，Baetselier博士及其合作人员在10月16日在线发表的 Sexually Transmitted Infections 杂志上解释道。该试剂也作为一种自我衣原体感染检测的检测在美国加州的里奥维斯塔由EnZtek诊断公司在销售。

　　研究人员在卢旺达进行了该项 Ring Plus 临床试验，该实验评估了该方法的敏感性和特异性，受试对象为137例为年龄在18至35周岁的未怀孕妇女。

　　通过跟现有衣原体检测金标准核酸扩增测试（NAAT）进行比较发现，由BioChekSwab快速分析检测9例均未发现一例阳性，显然，敏感性为0%。

　　据该研究报道，该快速检测法还产生4例假阳性的结果，而特异性为96.9%。

　　该检测方法的阳性预测值为0%，而阴性预测值为93.2%。当把该方法读取的cut-off值变为2倍时间时，在额外标本中发现了8例阳性，但是通过NAAT发现没有一例为阳性。

　　“如果该方法将提高敏感性/特异性，该检测将在任何环境中可以使用，尤其是在低收入且缺乏分子诊断检测的地区。不幸的是，可实际并非如此。”Baetselier博士说道。

　　Baetselier博士补充说道，“标签或认证如ISO-13485：2003和著名的CE标识给予了该方法的检测质量假的代表。对于有需求的人们，通过互联网的匿名搜索，这样的CE标志着实给人们对商品的可靠性和质量假的感觉。世界卫生组织对高负担疾病如HIV有一个有关体外诊断的诊断类资格预审，这是一个非常广泛的资格预审，但WHO也提到他们无法评估所有试验。。。不过，我还是认为，可在互联网上查到的方法至少应该得到独立审查。”

　　EnZtek诊断首席技术官Robert Herd在给路透社健康的邮件中说道，“迄今为止，我们有超过1700例的患者研究，并从另外的5个站点用PCR进行验证。这些研究是由世界范围内的一些包括PhD 和 MD组成的专业人士进行的。我们没有在卢旺达进行的该项研究的检测人员的检测口径，虽然我们知道他们还没到达专业医生水平，也就没有进行类似BioChekSwab（BCS）的研究。”

　　Robert Herd还列举几件有关该研究作者和EnZtek诊断公司之间的关系，他建议，应该对该项研究的研究质量进行质疑。

　　Robert Herd还指出“我们已经有两年没有销售衣原体有关的POCT了。这是因为PCR在世界范围的应用的普及。此外，我们已经在第三世界国家销售衣原体检测试剂长达20年，并且以相同的方式进行数以百万计的测试。这是至今以来我们收到的第一个大规模阴性反应。”

　　他总结道”这一刻，我们正在对所有的信件、研究信息、数据、凭证和任何有关这一问题的信息进行法律审查。“

　　澳大利亚昆士兰詹姆斯·库克大学的Dermot S. Hurly博士对2014年的两项针对沙眼衣原体测试的POCT（不包含BioChekSwab）进行回顾发现，存在同样的高假阴性和假阳性率。

　　在看完本份报告后，他总结道，“我看不到该项检测在任何情况下是有益的，它应该从市场中被移除。”

Point-of-Care Rapid Assay Lacks Sensitivity for Chlamydia Trachomatis

NEW YORK (Reuters Health) - The BioChekSwab rapid test for Chlamydia trachomatis showed a sensitivity of 0% in a study of 137 women in Rwanda.

"The assay received the CE label and is therefore sold as a reliable assay," Dr. Irith De Baetselier from Institute of Tropical Medicine in Antwerp, Belgium, told Reuters Health by email. "Unfortunately, we showed with this small study that the assay doesn't work at all in our setting."

The BioChekSwab uses an enzyme substrate that, when hydrolyzed by a C. trachomatis-specific peptide hydrolase, produces a fluorescence that can be read colorimetrically by adding a color-developing agent, Dr. De Baetselier and colleagues explain in Sexually Transmitted Infections, online October 16. The test is also marketed as SELFCheck Chlamydia by EnZtek Diagnostics Incorporated in Rio Vista, California.

The researchers assessed the sensitivity and specificity of this assay in the setting of the Ring Plus clinical trial in Rwanda, which included 137 nonpregnant women between 18 and 35 years old.

None of the nine samples positive for C. trachomatis by the gold-standard nucleic acid amplification testing (NAAT) was detected by the BioChekSwab Rapid Assay, yielding a sensitivity of 0%.

The rapid assay also generated four false-positive results, for a specificity of 96.9%, according to the report.

The rapid assay has a positive predictive value of 0% and a negative predictive value of 93.2%. Eight additional samples became positive after the assay cut-off reading time of 2 minutes, but none of these were positive by NAAT.

"If the assay would increase in sensitivity/specificity, the test would be surely useful in any setting, but in particular in low resource settings with no access to molecular testing," Dr. De Baetselier said. "Unfortunately, this isn't the case yet."

Dr. De Baetselier added, "Labels or certifications such as ISO-13485:2003 and the well-known CE label give a false representation of the quality of the assays. For people who are in need, want to get tested anonymously and search the internet, such a CE label gives a false feeling of reliability and quality. The WHO has a prequalification of diagnostics program for in vitro diagnostics for high-burden diseases such as HIV, which is very extensive, but as they mention they cannot assess all assays . . . However, I still believe that assays that are available over the internet should at least been reviewed independently."

Robert Herd, chief technology officer for EnZtek Diagnostics, told Reuters Health by email, "To date we have over 1,700 patients studied, and verified with PCR, from five additional sites. These studies were conducted by PhD and MD professionals, worldwide. We have no idea of the caliber of the testing personnel in Rwanda, although we understand they were not at the Doctor level, and had not conducted studies such as the BioChekSwab (BCS) study."

Herd also cited several pieces of correspondence between the authors and EnZtek that, he suggested, call into question the quality of the study.

Herd noted, "We have not sold the Point Of Care BCS for Chlamydia for almost two years. This is due to the prevalence of PCR testing throughout the world. Also, we have sold the chlamydia test into third world countries for over 20 years, and millions of tests in a bottle format. This is the first negative response we have received over that time."

"At this time," Herd concluded, "we are conducting a legal review of all correspondence, study information, data, credentials, and other issues regarding this contradictory issue."

Dr. Dermot S. Hurly from James Cook University in Queensland, Australia, reviewed two C. trachomatis point-of-care tests (not including BioChekSwab) in 2014 and found them similarly wanting due to high false-negative and false-positive rates.

After reading the current report, he concluded, "I cannot see any situation where this test would be useful. It should be removed from the market."