Bizzaro Nicola, Tonutti Elio, Tozzoli Renato, Villalta Danilo
Laboratory of Clinical Pathology, Hospital of Tolmezzo, Italy.
Clin Chem. 2007 Aug;53(8):1527-33. doi: 10.1373/clinchem.2007.087569. Epub 2007 Jun 22.
Measurement of antibodies to citrullinated peptides or proteins (CP) is a new test for the diagnosis of rheumatoid arthritis (RA). We analyzed the analytical characteristics and diagnostic accuracy of commercially available methods.
We studied 11 commercially available 2nd- and 3rd-generation methods that used various citrullinated antigen substrates: synthetic cyclic peptides, recombinant rat filaggrin, mutated human vimentin, and Epstein-Barr virus- or IgG-derived peptides. We assessed imprecision by measuring samples with low, intermediate, and high concentrations 5 times on each of 5 days. We measured CPs by each of the assays in 100 serum samples from patients with RA and in 202 samples from healthy persons or patients with other autoimmune, viral, or neoplastic diseases.
The between-run imprecision (CV) of the methods was between 0.4% and 22%, and the repeatability (within-run imprecision) was 0.5%-19%. The areas under the ROC curves varied between 0.79 (95% CI, 0.72-0.85) and 0.92 (0.88-0.95). At a fixed specificity of 98.5%, the sensitivities ranged from 41% (95% CI, 31%-51%) to 74% (64%-82%). Sensitivities and specificities varied markedly at the manufacturer's suggested cutoffs. Most false-positive results were recorded in patients with viral infections. The methods that use the original synthetic cyclic CP gave the best and very similar performances, although these methods use different components in their reagent sets (conjugate, type of substrate, dilution, and washing buffers). This finding shows that the antigenic source is the most important variable in determining the diagnostic accuracy of the methods.
The analytical imprecision and diagnostic accuracies of commercially available methods for the detection of anti-CP antibodies differ. Careful selection of methods is needed.
检测抗瓜氨酸化肽或蛋白（CP）抗体是诊断类风湿关节炎（RA）的一项新检测方法。我们分析了市售检测方法的分析特性和诊断准确性。
我们研究了11种市售的第二代和第三代检测方法，这些方法使用了各种瓜氨酸化抗原底物：合成环肽、重组大鼠丝聚蛋白、突变的人波形蛋白以及爱泼斯坦-巴尔病毒或IgG衍生肽。我们通过在5天中的每一天对低、中、高浓度样本各测量5次来评估不精密度。我们用每种检测方法对100份RA患者的血清样本以及202份健康人或患有其他自身免疫性、病毒性或肿瘤性疾病患者的样本进行CP检测。
这些方法的批间不精密度（CV）在0.4%至22%之间，重复性（批内不精密度）为0.5% - 19%。ROC曲线下面积在0.79（95%CI，0.72 - 0.85）至0.92（0.88 - 0.95）之间。在固定特异性为98.5%时，灵敏度范围为41%（95%CI，31% - 51%）至74%（64% - 82%）。在制造商建议的临界值下，灵敏度和特异性有显著差异。大多数假阳性结果出现在病毒感染患者中。使用原始合成环CP的方法表现最佳且非常相似，尽管这些方法在试剂组中使用了不同成分（缀合物、底物类型、稀释液和洗涤缓冲液）。这一发现表明，抗原来源是决定这些方法诊断准确性的最重要变量。
市售检测抗CP抗体方法的分析不精密度和诊断准确性存在差异。需要谨慎选择检测方法。
