[Evaluation of serology as a diagnostic method for Helicobacter pylori infection in the local population of Guayaquil].
BACKGROUND
The infection with Helicobacter pylori (H. pylori), and the diagnostic efficacy of the serologic tests has certain variability among the different geographic regions.


OBJECTIVE
The objective of the present work was to find the local validation of serological methods for diagnosis of H. pylori infection and to determine the best cutoff value for the local population.


METHODS
Forty-eight patients were evaluated, 27 males and 21 females, with a mean age of 29.2 years. On each patient, 3 tests for H. pylori diagnosis were performed: IgG serology, IgA serology and histology. We performed IgG and IgA serologic test for H. pylori infection and a histological examination for each patient. Efficacy parameters as well as the ROC curve were obtained for the IgG and IgA serology using histology as the gold standard.


RESULTS
The cutoff point with the highest efficacy for IgG serology was 16 U/ml (sensitivity 81%, specificity 65%, positive predictive value 81%, negative predictive value 65%, and accuracy 75%), and for IgA serology was 17 U/ml (sensitivity 61%, specificity 53%, positive predictive value 70%, negative predictive value 43%, and accuracy 58%). The area under the curve was 67.1% (CI 95%: 50 to 84.1) and 54.4% (CI 95%: 38.3 to 72.5) for IgG and IgA respectively.


CONCLUSIONS
The serology is a valuable tool in our population with high prevalence of H. pylori, especially due to its low cost and easy performance, but a reduction ofthe cutoff value was necessary to obtain more sensibility and a more adequate identification of true positives cases.
Zapatier
Jorge A
JA
Instituto de Enfermedades Digestivas, Fundación Esperanza, Guayaquil, Ecuador.
Gómez
Néstor A
NA
Vargas
Paola E
PE
Maya
Susana V
SV
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004484:Ecuador; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods / Q000592:standards; D014505:Urban Population
D007070:Immunoglobulin A; D007074:Immunoglobulin G