RESUMEN
TITLE: ABO blood groups as risk factor in Helicobacter pylori infection.OBJECTIVE: To asses the relation between ABO blood groups and Helicobacter pylori (Hp) infection. METHODS: The present is a case and control study. A study population of dyspeptic patients who underwent upper gastrointestinal endoscopy was selected. Four biopsies were taken from the antrum and the body of the stomach and blood group was typified. Patients with gastrectomy, gastric cancer, treated for Hp infection in the previous six months or without blood group typification were excluded. The population sample was found using EPIINFO 5.1 program. We called case to every patient with Hp (+) biopsy and control all with Hp (-) biopsy. The risk of the infection was calculated with the OR (Odds ratio) and the study sample was compared with the blood bank control group using the Chi-square test (p<0.005).RESULTS: 367 patients were included (202 female). Age average was 45,06 years. 276 (75,2%) were Hp (+). There were not statistically significant differences in the distribution of ABO blood groups between the study population and the blood bank control. When we compared the ABO blood distribution between patients Hp (+) and Hp (-) we found significant differences for blood group O (p=0.004) and blood group A (p=0.03). Statistical analysis revealed an OR=2,22 for the blood group O and OR=0,5 for the blood group A.CONCLUSIONS: 1) The ABO blood group distribution is different in patients with Hp infection compared with those without Hp infection. 2) Blood group O would be a moderate risk factor for infection by Helicobacter pylori.