Epidemiology of non-erosive reflux disease.

Non-erosive reflux disease (NERD) is a relatively new entity, the definition of which has been evolving and involves the use of symptoms, endoscopy, and objective evidence of reflux or reflux-related damage. The closest entity to NERD that is examined by available epidemiologic studies is defined by the presence of gastroesophageal reflux disease (GERD) symptoms in the absence of esophageal erosions or Barrett's esophagus. In this review, I identified two population-based studies, one non-community study, and several endoscopy-based studies that provided information on several aspects of NERD. Most of GERD is NERD (50-85%), and therefore one can estimate 11-12% of the general population and considerably higher proportions of patients presenting to endoscopy (37-87%) may have NERD. Risk factors for NERD including absence of hiatus hernia, low BMI, and presence of Helicobacter pylori indicate that it is a 'milder' part of the GERD spectrum. Other associations of NERD include younger age, female sex, and psychological comorbidities that resemble those of functional gut disorders. The temporal trends in NERD are unclear, and are probably increasing because GERD symptom prevalence has increased.