根据刚刚发表于《内科学年鉴》(Annals of Internal Medicine)上的一项荟萃分析的结果，粪便免疫化学检查(FIT)对结直肠癌(CRC)的总体诊断准确度可达95%(Ann. Intern. Med. 2014;160:171-81)。 日前发表于Annals of Internal Medicine上的一项荟萃分析的结果显示，粪便免疫化学检查(FIT)对结直肠癌(CRC)的总体诊断准确度可达95。在美国、欧洲和亚洲，这项检查早已开始取代粪便潜血检查(FOBT)用于国家筛查项目。FIT检出CRC的敏感性和特异性分别达到79%和94%。 美国Kaiser Permanente研究部门的Douglas Corley博士等人认为，这一系统综述和荟萃分析提示， FITs检验CRC具有高精确度、高特异性和中等程度的高敏感性。研究者称，与FOBT相比，FIT检出CRC和腺瘤的敏感性都更强，对于家庭使用也更为实用，仅需要1份或2份粪便样品，也不需要特殊的饮食或药物限制。 尽管 FITs 用于群体筛查可能更方便，但关于其诊断性能的报告却并不一致。因此，研究者进行了这项荟萃分析，目的是确定这项检测的总体诊断准确度和影响检测性能的因素。分析共纳入19项试验，包含113,000多例受试者，并且提供了关于在美国使用的8种不同FIT的数据。 除FIT的敏感性和特异性数据之外，研究者还计算了阳性和阴性似然率(LR)，分别评估这些检查“纳入”或“排除”CRC诊断的能力。为阳性LR设定的截点为数值＞5，对于阴性LR为0.2。来自这些试验的汇总数据显示阳性LR为13.10，阴性LR为0.23。 FIT样品数增加不会影响FIT对CRC的总敏感性、特异性、阳性LR或阴性LR。研究中评估的不同FIT检测试剂的性能也无显著差异。不过研究者承认，因为多数研究未进行头对头比较，因此对这些结果的解释需谨慎。研究者表示，诊断性能受到用于确定阳性检测结果的临界值的影响，这可能影响卫生系统对检测手段的选择。 卫生系统希望优化定量 FITs的使用，但应考虑权衡敏感性增加（降低阳性检测结果的临界值）和导致阳性结果数增加之间的矛盾。因阳性检测结果提示需进一步检查，故阳性结果数增加可能对结肠镜资源的使用造成很大影响。研究者推荐卫生系统还应关注那些比较单一或重复检验的研究，因为当前数据未提供关于样品数量对于FITs性能影响的确切结论。 By: SARA FREEMAN, Internal Medicine News Digital Network Fecal immunochemical tests have an overall diagnostic accuracy of 95% for the detection of colorectal cancer, according to the results of a meta-analysis just published in the Annals of Internal Medicine. The tests, which have already begun to replace the fecal occult blood test (FOBT) in national screening programs in the United States, Europe, and Asia, were found to be 79% sensitive and 94% specific for CRC. "This systematic review and meta-analysis suggests that FITs [fecal immunochemical tests] have high accuracy, high specificity, and moderately high sensitivity for detection of CRC," Dr. Douglas Corley of the Kaiser Permanente division of research in Oakland, Calif., and his associates wrote (Ann. Intern. Med. 2014;160:171-81). FITs are more sensitive at detecting both CRC and adenomas than the FOBT, they maintained, and are also more practical for people to perform at home, requiring only one or two stool samples and no special dietary or medication restrictions. Despite a greater potential ease of use for mass screening, reports on the diagnostic performance of FITs have been inconsistent, the investigators explained. They therefore performed the meta-analysis to determine the overall diagnostic accuracy and factors affecting the tests’ performance. Nineteen trials were included that involved more than 113,000 individuals and provided data on eight different FITs available for use in the United States. In addition to the sensitivities and specificities of FITs, positive and negative likelihood ratios (LR) were calculated to assess the ability of the tests to respectively "rule in" or "rule out" a diagnosis of CRC. The threshold set for a positive LR was a value above 5 and for a negative LR was 0.2. Pooled data from the trials showed a positive LR of 13.10 and a negative LR of 0.23. Increasing the number of FIT samples did not affect the pooled sensitivities, specificities, positive LRs, or negative LRs of FITs for CRC. There also was no great difference in performance between the FIT brands evaluated in the studies. Dr. Corley and his associates pointed out, however, that head-to-head comparisons were not included in most studies so this finding should be interpreted with caution. Diagnostic performance was affected by the cutoff values used to define a positive test, which might influence which test health systems decide to use, the researchers said. "Health systems wishing to optimize use of a quantitative FIT should consider the tradeoff between increasing sensitivity (by lowering the cutoff threshold for a positive test) and the resulting increase in the number of positive results," they wrote. The latter could significantly impact colonoscopy resources if more procedures were indicated by a positive test. The researchers recommended that health systems also look at individual studies comparing single or repeat testing, as the current data do not provide a definitive answer on the effect of sample number on the performance of FITs. The National Institute of Diabetes and Digestive and Kidney Diseases and the National Cancer Institute funded the research. |
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