Laboratory Medicine, Immunology, University Hospitals Leuven, Catholic University of Leuven, Leuven, Belgium.
Clin Gastroenterol Hepatol. 2013 Apr;11(4):398-403; quiz e32. doi: 10.1016/j.cgh.2012.10.025. Epub 2012 Oct 25.
BACKGROUND & AIMS: The European Society for Pediatric Gastroenterology and Nutrition proposed guidelines for the diagnosis of celiac disease, stating that duodenal biopsy is no longer needed if patients have symptoms and levels of immunoglobulin A anti-tissue transglutaminase (IgA anti-tTG) more than 10-fold the cut-off value. We evaluated the accuracy of this guideline in a well-characterized population using different commercial assays.
We analyzed levels of IgA anti-tTG in serum samples from 104 consecutive pediatric and adult patients who were not deficient in IgA and were diagnosed with celiac disease from August 1, 2000, to December 31, 2009. We also analyzed serum samples from 537 consecutive patients without celiac disease (controls), collected from May 1, 2004, to October 12, 2006, who underwent intestinal biopsy analysis. Serum levels of antibodies were quantified using assays from Bio-Rad, INOVA, Genesis, and Thermo Fisher.
The likelihood ratio (probability of a specific result in patients divided by the probability of the same result in controls) for celiac disease increased with levels of IgA anti-tTG in all assays. Depending on the assay, the likelihood ratio for levels greater than 10-fold the cut-off value ranged from 111 to 294. The percentage of patients with celiac disease with levels of IgA anti-tTG greater than 10-fold the cut-off value ranged from 41% to 61%, depending on the assay. For levels of anti-tTG greater than 10-fold the cut-off value, the post-test probabilities for celiac disease (probability of disease, based on pretest probability and test result) were, depending on the assay, 89%-96% and 53%-75% for pretest probabilities (probability of disease depending on symptoms) of 7% and 1%, respectively.
To diagnose celiac disease based on serologic factors, it might be best to define thresholds for levels of IgA anti-tTG based on a predefined likelihood ratio or post-test probability, instead of a multiple of a cut-off value. Patients with a high pretest probability and levels of anti-tTG greater than 10-fold the cut-off value have a high probability for having celiac disease, aiding clinical decision making.
欧洲儿科胃肠病学和营养学会提出了乳糜泻的诊断指南，指出如果患者有症状且免疫球蛋白 A 抗组织转谷氨酰胺酶（IgA 抗 tTG）水平超过截断值 10 倍以上，则不再需要进行十二指肠活检。我们使用不同的商业检测方法，在一个特征明确的人群中评估了该指南的准确性。
我们分析了 2000 年 8 月 1 日至 2009 年 12 月 31 日期间连续 104 例非 IgA 缺乏且经诊断为乳糜泻的儿科和成年患者血清样本中的 IgA 抗 tTG 水平。我们还分析了 2004 年 5 月 1 日至 2006 年 10 月 12 日期间连续 537 例无乳糜泻（对照组）患者的血清样本，这些患者进行了肠活检分析。使用 Bio-Rad、INOVA、Genesis 和 Thermo Fisher 的检测方法对抗体进行定量分析。
所有检测方法中，IgA 抗 tTG 水平与乳糜泻的可能性比值（患者特定结果的概率除以对照组中相同结果的概率）均增加。根据检测方法的不同，大于截断值 10 倍的可能性比值范围为 111 至 294。根据检测方法的不同，IgA 抗 tTG 水平大于截断值 10 倍的乳糜泻患者比例为 41%至 61%。对于大于截断值 10 倍的抗 tTG 水平，基于预测试概率和测试结果的乳糜泻后测试概率（基于预测试概率和测试结果的疾病概率）分别取决于检测方法，为 89%-96%和 53%-75%，预测试概率（取决于症状的疾病概率）分别为 7%和 1%。
基于血清学因素诊断乳糜泻，根据预先定义的可能性比值或后测试概率而不是截断值的倍数来定义 IgA 抗 tTG 水平的阈值可能更为合适。具有高预测试概率和大于截断值 10 倍的抗 tTG 水平的患者患有乳糜泻的可能性很高，有助于临床决策。
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