Coelho Luiz Gonzaga Vaz, Silva Arilto Eleutério da, Coelho Maria Clara de Freitas, Penna Francisco Guilherme Cancela e, Ferreira Rafael Otto Antunes, Santa-Cecilia Elisa Viana
Instituto Alfa de Gastroenterologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
Arq Gastroenterol. 2011 Apr-Jun;48(2):104-8. doi: 10.1590/s0004-28032011000200004.
The standard doses of (13)C-urea in (13)C-urea breath test is 75 mg.
To assess the diagnostic accuracy of (13)C-urea breath test containing 25 mg of (13)C-urea comparing with the standard doses of 75 mg in the diagnosis of Helicobacter pylori infection.
Two hundred seventy adult patients (96 males, 174 females, median age 41 years) performed the standard (13)C-urea breath test (75 mg (13)C-urea) and repeated the (13)C-urea breath test using only 25 mg of (13)C-urea within a 2 week interval. The test was performed using an infrared isotope analyzer. Patients were considered positive if delta over baseline was >4.0‰ at the gold standard test.
One hundred sixty-one (59.6%) patients were H. pylori negative and 109 (40.4%) were positive by the gold standard test. Using receiver operating characteristic analysis we established a cut-off value of 3.4% as the best value of 25 mg (13)C-urea breath test to discriminate positive and negative patients, considering the H. pylori prevalence (95% CI: 23.9-37.3) at our setting. Therefore, we obtained to 25 mg (13)C-urea breath test a diagnostic accuracy of 92.9% (95% CI: 88.1-97.9), sensitivity 83.5% (95% CI: 75.4-89.3), specificity 99.4% (95% CI: 96.6-99.9), positive predictive value 98.3% (95% CI: 92.4-99.4), and negative predictive value 93.0% (95% CI: 88.6-96.1).
Low-dose (13)C-urea breath test (25 mg (13)C-urea) does not reach accuracy sufficient to be recommended in clinical setting where a 30% prevalence of H. pylori infection is observed. Further studies should be done to determine the diagnostic accuracy of low doses of (13)C-urea in the urea breath test.
碳-13尿素呼气试验中碳-13尿素的标准剂量为75毫克。
评估含25毫克碳-13尿素的碳-13尿素呼气试验与75毫克标准剂量在诊断幽门螺杆菌感染方面的诊断准确性。
270例成年患者（96例男性，174例女性，中位年龄41岁）进行标准碳-13尿素呼气试验（75毫克碳-13尿素），并在2周内间隔重复进行仅使用25毫克碳-13尿素的碳-13尿素呼气试验。使用红外同位素分析仪进行检测。在金标准检测中，如果基线差值>4.0‰，则患者被视为阳性。
根据金标准检测，161例（59.6%）患者幽门螺杆菌阴性，109例（40.4%）患者阳性。使用受试者工作特征分析，考虑到我们研究环境中幽门螺杆菌的患病率（95%可信区间：23.9 - 37.3），我们确定25毫克碳-13尿素呼气试验区分阳性和阴性患者的最佳截断值为3.4%。因此，我们得出25毫克碳-13尿素呼气试验的诊断准确性为92.9%（95%可信区间：88.1 - 97.9），敏感性为83.5%（95%可信区间：75.4 - 89.3），特异性为99.4%（95%可信区间：96.6 - 99.9），阳性预测值为98.3%（95%可信区间：92.4 - 99.4），阴性预测值为93.0%（95%可信区间：88.6 - 96.1）。
低剂量碳-13尿素呼气试验（25毫克碳-13尿素）在观察到幽门螺杆菌感染患病率为30%的临床环境中，其准确性不足以被推荐。应进行进一步研究以确定低剂量碳-13尿素在尿素呼气试验中的诊断准确性。
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