Validation of the 13c-urea breath test for the initial diagnosis of helicobacter pylori infection and to confirm eradication after treatment.
OBJECTIVE
the breath test with 13C-urea (UBT) is a method widely used in Spain, but its diagnostic accuracy has not been evaluated in a clinical trial until now. Our objective was to validate the UBT (TAU-KIT) both as an initial diagnostic method for the detection of H. pylori infection and as a method to confirm eradication.


METHODS
a multi-centre study in 7 Spanish hospitals was performed. A group of dyspeptic patients who had not previously received eradication treatment was included, and a second group of patients with gastric ulcer or upper gastrointestinal bleeding due to peptic ulcer was also included (eradication of H. pylori was confirmed 6 to 8 weeks after treatment completion with omeprazole, clarithromycin and amoxycillin). In both groups an endoscopy was performed with biopsies for histology and rapid urease test. Patients were considered infected if both tests yielded positive results, and not infected when both tests were negative. The UBT 13C-urea (TAU-KIT, Isomed S.L., Madrid, Spain) was performed with citric acid and 100 mg of 13C-urea. The pathologist and persons responsible for endoscopy, urease test and UBT were all unaware of the results from the other diagnostic methods.


RESULTS
in the pre-treatment group (36 patients) the prevalence of H. pylori was 72%, the area under the ROC curve for the diagnosis of infection with the UBT was 0.99, and the best cut-off point was 5 units, with the following results: sensitivity= 96% (95% CI = 81-99%), specificity= 100% (69-100%), positive predictive value (PPV) = 100% (87-100%), negative predictive value (NPV) = 92% (59-100%), likelihood ratio (LR) + = infinity, and LR- = 0.04. In the post-treatment group (85 patients) the prevalence of H. pylori was 16%, the area under the ROC curve was 0.99, and the best cut point was 4.6, with the following results: sensitivity= 100% (77-100%), specificity = 97% (90-99%), PPV = 88% (62-98%), NPV = 100% (95-100%), LR+ = 35, and LR- = 0.


CONCLUSIONS
UBT provides excellent accuracy both for the initial diagnosis of H. pylori infection and to confirm eradication after treatment.
Gisbert
J P
JP
Servicio de Aparato Digestivo. Hospital de la Princesa. Madrid. Spain. gisbert@meditex.es
Ducons
J
J
Gomollón
F
F
Domínguez-Muñoz
J E
JE
Borda
F
F
Miño
G
G
Jiménez
I
I
Vázquez
M A
MA
Santolaria
S
S
Gallego
S
S
Iglesias
J
J
Pastor
G
G
Hervás
A
A
Pajares
J M
JM
D000328:Adult; D000658:Amoxicillin / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000897:Anti-Ulcer Agents / Q000627:therapeutic use; D001944:Breath Tests / Q000379:methods; D002247:Carbon Isotopes; D017291:Clarithromycin / Q000627:therapeutic use; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000188:drug therapy*; D016480:Helicobacter pylori; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use; D010406:Penicillins / Q000627:therapeutic use; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013997:Time Factors; D014508:Urea / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D002247:Carbon Isotopes; D010406:Penicillins; D000658:Amoxicillin; D014508:Urea; D017291:Clarithromycin; D009853:Omeprazole