自肌钙蛋白被发现以来，急性心肌梗死（AMI）的诊断有了革命性的变化。值得注意的是，传统的肌钙蛋白检测法的检测下限过高，在AMI发作早期，肌钙蛋白水平往往低于检测下限。这一缺陷也直接导致了部分AMI患者得不到及时的诊断，延误了病情的治疗。
此外，由于肌钙蛋白阴性并不能作为排除AMI的依据，急诊科医师不得不对胸痛患者进行留观，进行进一步的检查以排除或确诊AMI。据估计，在所有因胸痛而留观的患者中，只有约25%的患者最终会被确诊为AMI。因此，迫切需要一种更加灵敏的肌钙蛋白检测技术，以便能使胸痛患者对AMI进行及时的诊断或排除。
近年来，肌钙蛋白检测技术的一大进步就是高敏肌钙蛋白的出现。所谓高敏肌钙蛋白，就是其检测下限较传统的肌钙蛋白更低，能检测出极低水平的肌钙蛋白。国外多家公司相继研发了高敏肌钙蛋白检测方法，罗氏的Elecsys高敏肌钙蛋白T（hs-cTnT）检测系统是其中较为成熟的方法。
过去的几年里，使用该检测系统诊断AMI的报道较多，但结论各不一致。鉴于此，英国埃克塞特大学和皇家康瓦尔医院的研究人员开展了一项meta分析，对hs-cTnT诊断AMI的性能进行了评价，研究成果于2015年1月21日在线发表于BMJ。
该研究纳入了23项发表于2006年1月至2013年12月前的研究，采用双变量模型对研究结果进行了meta分析。结果表明，若以14 ng/L（hs-cTnT在健康个体中99%分布上限）作为诊断界值，则其诊断AMI的敏感性和特异性分别为89.5%和77.1%。若以3-5 ng/L（hs-cTnT检测方法学的下限）作为诊断界值，则其诊断敏感性和特异性分别为97.4%和42.4%。
由于该meta分析的验前概率为0.21，因此该研究的结论可以简单解读为：假定有100个因胸痛而就诊的患者，最终大约有21个患者会被诊断为AMI。若以14 ng/L作为AMI的诊断界值，则21名AMI患者中的2名患者会被漏诊，79名非心肌梗死患者中的18例患者会被误诊。若以3-5 ng/L作为诊断AMI的界值，则只有不到1名AMI患者会被漏诊，46名非AMI患者会被误诊。
需要强调的是，目前的高敏肌钙蛋白检测系统较多，检测原理、报告单位和检测性能各不一致。上述研究仅仅针对罗氏的Elecsys hs-cTnT检测系统，不能据此认为其它高敏肌钙蛋白检测系统也具有相同的诊断性能。此外，由于纳入研究中的大部分研究对象均在胸痛发生3小时以后才就诊，尚不能确定胸痛发生3小时内hs-cTnT是否还有相同的诊断效率。 |
原文信息：
Diagnostic accuracy of single baseline measurement of Elecsys Troponin T high-sensitive assay for diagnosis of acute myocardial infarction in emergency department: systematic review and meta-analysis
BMJ. 2015 Jan 20;350:h15. doi: 10.1136/bmj.h15.
Abstract OBJECTIVE: To obtain summary estimates of the accuracy of a single baseline measurement of the Elecsys Troponin T high-sensitive assay (Roche Diagnostics) for the diagnosis of acute myocardial infarction in patients presenting to the emergency department. DESIGN: Systematic review and meta-analysis of diagnostic test accuracy studies. DATA SOURCES: Medline, Embase, and other relevant electronic databases were searched for papers published between January 2006 and December 2013. STUDY SELECTION: Studies were included if they evaluated the diagnostic accuracy of a single baseline measurement of Elecsys Troponin T high-sensitive assay for the diagnosis of acute myocardial infarction in patients presenting to the emergency department with suspected acute coronary syndrome. STUDY APPRAISAL AND DATA SYNTHESIS: The first author screened all titles and abstracts identified through the searches and selected all potentially relevant papers. The screening of the full texts, the data extraction, and the methodological quality assessment, using the adapted QUADAS-2 tool, were conducted independently by two reviewers with disagreements being resolved through discussion or arbitration. If appropriate, meta-analysis was conducted using the hierarchical bivariate model. RESULTS: Twenty three studies reported the performance of the evaluated assay at presentation. The results for 14 ng/L and 3-5 ng/L cut-off values were pooled separately. At 14 ng/L (20 papers), the summary sensitivity was 89.5% (95% confidence interval 86.3% to 92.1%) and the summary specificity was 77.1% (68.7% to 83.7%). At 3-5 ng/L (six papers), the summary sensitivity was 97.4% (94.9% to 98.7%) and the summary specificity was 42.4% (31.2% to 54.5%). This means that if 21 of 100 consecutive patients have the target condition (21%, the median prevalence across the studies), 2 (95% confidence interval 2 to 3) of 21 patients with acute myocardial infarction will be missed (false negatives) if 14 ng/L is used as a cut-off value and 18 (13 to 25) of 79 patients without acute myocardial infarction will test positive (false positives). If the 3-5 ng/L cut-off value is used, <1 (0 to 1) patient with acute myocardial infarction will be missed and 46 (36 to 54) patients without acute myocardial infarction will test positive. CONCLUSIONS: The results indicate that a single baseline measurement of the Elecsys Troponin T high-sensitive assay could be used to rule out acute myocardial infarction if lower cut-off values such as 3 ng/L or 5 ng/L are used. However, this method should be part of a comprehensive triage strategy and may not be appropriate for patients who present less than three hours after symptom onset. Care must also be exercised because of the higher imprecision of the evaluated assay and the greater effect of lot-to-lot reagent variation at low troponin concentrations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42013003926.
原文链接： http://www.bmj.com/content/350/bmj.h15 |
