[C-13]-urea breath test for assessment of cure of Helicobacter pylori infection at 1 month after treatment

Although the [C-13]-urea breath test has been reported to provide high spec ificity and sensitivity, its reliability in determination of cure, includin g when and how the assessment of cure is made, is not fully established. He re we evaluate the reliability of judgment of cure after 1 month of therapy using the [C-13]-urea breath test, including the appropriate time to asses s its cure. Our subjects were 199 H. pylori-infected patients (144 men and 55 women; 50.5 +/- 0.76 years) who underwent cure therapy, took the breath test at 1 month, and underwent both the breath test and invasive tests usin g endoscopy at 6 months after completion of therapy. Accuracy of the breath test in judgment of cure at 1 month was investigated by comparing the resu lts at 1 month with those at 6 months when cut-off value of the breath lest was set at 5 parts per thousand. Chronologic alterations of the Delta(13)C value were also analyzed in cured patients who underwent the breath test a t 1, 3, and 6 months. In 167 (94.9%) of 176 patients whose breath test valu es were less than 5 parts per thousand, cure was reconfirmed at 6 months. I n 14 (60.9%) of 23 patients whose values were greater than 5 parts per thou sand, cure was demonstrated at 6 months. The mean Delta(13)C values of 33 c ured patients who took the breath test at 1 month and repeated the breath t est at 3 and 6 months for any reasons were 4.14 +/- 0.74 parts per thousand , 2.02 +/- 0.23 parts per thousand, and 1.72 +/- 0.19 parts per thousand, r espectively, and the value at 3 months was significantly smaller than that at 1 month. The reliability of assessment of cure by only the breath test a t 1 month was sufficiently high (94.9%) once the patients were judged to be cured. However, because the breath test at 1 month yielded a high false-po sitive rate and the breath test values at 3 and 6 months were similar, eval uation of cure of H. pylori infection by the [C-13]-urea breath test should preferably be done at 3 months after treatment to minimize false-positive results, or the concept of a borderline group should be established for pat ients with positive but relatively high Delta(13)C values (5-10 parts per t housand) who repeated the breath test 3 months after treatment.