[Validation of an ammonia breath test for the diagnosis of Helicobacter pylori infection in patients with dyspepsia at Hospital Cayetano Heredia]. / Validación de una prueba de amonio en aliento para el diagnóstico de la infección por Helicobacter pylori en pacientes del Hospital Cayetano Heredia.

Objetive: To determine the diagnostic validity of an ammonia breath test for Helicobacter pylori infection in patients who undergo an upper gastrointestinal endoscopy at Hospital Cayetano Heredia. MATERIAL AND METHODS: From April to December 2014, 155 patients were evaluated with the ammonia breath test and compared with a histological evaluation of the gastric biopsies as the gold standard. Data were evaluated using Microsoft Excel and STATA 14 to build a ROC curve. RESULTS: The patients were predominantly female (71%), with a median age of 53 years (18-84) and a Helicobacter pylori prevalence of 51.6%. The ammonia breath test, when compared to the gastric biopsy has a 70% sensitivity, 36% specificity, 53.8% positive predictive value, 36% negative predictive value, 1.15 positive likelihood ratio and 0.75 negative likelihood ratio. According to the ROC curve, there is not an optimal cut off value and the area under the curve was 0.5517. CONCLUSIONS: The ammonia breath test evaluated on this study does not have diagnostic accuracy and is not recommended as a diagnostic tool for Helicobacter pylori infection.

Validación de una prueba de amonio en aliento para el diagnóstico de la infección por Helicobacter pylori en pacientes del Hospital Cayetano Heredia / Validation of an ammonia breath test for the diagnosis of Helicobacter pylori infection in patients with dyspepsia at Hospital Cayetano Heredia

Objetivo: Determinar la validez diagnóstica de una prueba de amonio en aire espirado para la infección por Helicobacter pylori en pacientes a los que se le realiza una endoscopía digestiva alta en el Hospital Cayetano Heredia. Material y métodos: De abril a diciembre del 2014 se evaluó a 155 pacientes con una prueba de amonio en aliento y la evaluación histopatológica de las biopsias de estómago (considerada como el patrón de oro) tomadas durante la endoscopía. Los datos fueron analizados en Microsoft Excel y STATA 14 para construir una curva ROC. Resultados: Los pacientes fueron predominantemente mujeres (71%), con una edad media de 53 años (18-84) y una prevalencia de Helicobacter pylori de 51,6%. Al comparar la prueba de amonio en aire espirado con la prueba histológica se obtiene una sensibilidad de 70%, especificidad de 36%, valor predictivo positivo de 53,8%, valor predictivo negativo de 36%, índice de probabilidad positivo de 1,15 e índice de probabilidad negativo de 0,75. De acuerdo a la curva ROC, no se encontró un punto de corte óptimo con adecuados valores de sensibilidad y especificidad y el área bajo la curva es de 0,5517. Conclusiones: Esta prueba de amonio en aliento (aire espirado) no presenta poder diagnóstico y no se recomienda como una herramienta para el diagnóstico de la infección por Helicobacter pylori.

Objetive: To determine the diagnostic validity of an ammonia breath test for Helicobacter pylori infection in patients who undergo an upper gastrointestinal endoscopy at Hospital Cayetano Heredia. Material and methods: From April to December 2014, 155 patients were evaluated with the ammonia breath test and compared with a histological evaluation of the gastric biopsies as the gold standard. Data were evaluated using Microsoft Excel and STATA 14 to build a ROC curve. Results: The patients were predominantly female (71%), with a median age of 53 years (18-84) and a Helicobacter pylori prevalence of 51.6%. The ammonia breath test, when compared to the gastric biopsy has a 70% sensitivity, 36% specificity, 53.8% positive predictive value, 36% negative predictive value, 1.15 positive likelihood ratio and 0.75 negative likelihood ratio. According to the ROC curve, there is not an optimal cut off value and the area under the curve was 0.5517. Conclusions: The ammonia breath test evaluated on this study does not have diagnostic accuracy and is not recommended as a diagnostic tool for Helicobacter pylori infection.