AIM: To investigate the influence of proton pump inhibitors(PPIs) exposure on the diagnosis of Helicobacter pylori(H. pylori) gastritis and intestinal metaplasia.METHODS: Chronic PPI use is associated with masking of H. pylori infection. Patients with H. pylori infection are predisposed to gastric and duodenal ulcers, and long-term infection with this organism has been associated with gastric mucosal atrophy and serious long-term complications, such as gastric lymphoma and adenocarcinoma. Three hundred patients diagnosed with gastritis between January 2008 and April 2010 were included in our study. The computerized medical database of these patients was reviewed retrospectively in order to assess whether the type of gastritis diagnosed(H. pylori vs non-H. pylori gastritis) is influenced by PPI exposure. H. pylori density was graded as low, if corresponding to mild density following the Updated Sydney System, or high, if corresponding to moderate or severe densities in the Updated Sydney System.RESULTS: Patients were equally distributed between males and females with a median age at the time of diagnosis of 50 years old(range: 20-87). The histological types of gastritis were classified as H. pylori gastritis(n = 156, 52%) and non-H. pylori gastritis(n = 144, 48%). All patients with non-H. pylori gastritis had inactive chronic gastritis. Patients with no previous PPI exposure were more likely to be diagnosed with H. pylori gastritis than those with previous PPI exposure(71% vs 34.2%, P < 0.001). Intestinal metaplasiawas more likely to be detected in the latter patients(1.4% vs 6.5%, P = 0.023). Multivariate analysis has also demonstrated that in the presence of previous PPI exposure(OR = 0.217, 95%CI: 0.123-0.385), GERD(OR = 0.317, 95%CI: 0.132-0.763, P = 0.01), alcohol intake(OR = 0.396, 95%CI: 0.195-0.804, P = 0.01), the detection of H. pylori was less likely. Chronic use of PPIs may mask H. pylori infections promoting the diagnosis of non-H. pylori gastritis and leads to a significant drop in H. pylori densities and to an increased risk of intestinal metaplasia.CONCLUSION: The use of PPIs masks H. pylori infection, promotes the diagnosis of non-H. pylori inactive chronic gastritis diagnosis, and increases the incidence of intestinal metaplasia. AIM: To investigate the influence of proton pump inhibitors (PPIs) exposure on the diagnosis of Helicobacter pylori (H. pylori) gastritis and intestinal metaplasia. METHODS: Chronic PPI use is associated with masking of H. pylori infection. Patients with H. pylori infection are predisposed to gastric and duodenal ulcers, and long-term infection with this organism has been associated with gastric mucosal atrophy and serious long-term complications, such as gastric lymphoma and adenocarcinoma. Three hundred patients diagnosed with gastritis between January 2008 and April 2010 The computerized medical database of these patients was reviewed retrospectively in order to assess whether the type of gastritis diagnosed (H. pylori vs non-H. pylori gastritis) is influenced by PPI exposure. H. pylori density was graded as low, if corresponding to mild density the following Sydney System, or high, if corresponding to moderate or severe densities in the Updated Sydne y System .RESULTS: Patients were equally distributed between males and females with a median age at the time of diagnosis of 50 years old (range: 20-87). The histological types of gastritis were classified as H. pylori gastritis (n = 156 , 52%) and non-H. pylori gastritis (n = 144, 48%). All patients with non-H. Pylori gastritis had inactive chronic gastritis. Patients with no previous PPI exposure were more likely to be diagnosed with H. pylori Gastritis compared with those with previous PPI exposure (71% vs 34.2%, P <0.001). Intestinal metaplasia was more likely to be detected in the latter patients (1.4% vs 6.5%, P = 0.023) presence of previous PPI exposure (OR = 0.217, 95% CI: 0.123-0.385), GERD (OR = 0.317, 95% CI: 0.132-0.763, P = 0.01) -0.804, P = 0.01), the detection of H. pylori was less likely. Chronic use of PPIs may mask H. pylori infections promoting the diagnosis of non-H. pylori gastritis and leads to a significant drop in H. pylori densities and to an increased risk of intestinal metaplasia. CONCLUSION: The use of PPIs masks H. pylori infection, promotes the diagnosis of non-H. pylori inactive chronic gastritis diagnosis, and increases the incidence of intestinal metaplasia.