GASTROESOPHAGEAL REFLUX DISEASE OVERVIEW
Gastroesophageal reflux disease (GERD) is a chronic disorder involving pathologic retrograde flow of gastric contents into the esophagus. In 2006, an international group of 44 experts known as the Montreal Consensus defined GERD as “a condition which develops when the reflux of stomach contents causes troublesome symptoms and/or complications.”1 This definition was chosen to allow for patients to be diagnosed independent of the technology used during evaluation. Nonerosive reflux disease (NERD) is defined as classic GERD symptoms in the absence of mucosal complications, and may2–4 account for 30% to 70% of patients presenting for endoscopy with reflux symptoms.
Until 2006, when the definition of GERD became more standardized, varying frequency rates were reported. A systematic review performed in 2005 identified a prevalence rate between 10% and 20% in Europe and the United States, and less than 5% in Asia.5 These findings of regional variation were updated and confirmed in 2014 by the same group. Occurrence of at least once-weekly episodes of heartburn or regurgitation or a diagnosis of GERD as defined by the Montreal Consensus or a physician was found to be18.1% to 27.8% in North America, 23.0% in South America, 8.8% to 25.9% in Europe, and 8.7% to 33.1% in the Middle East. In East Asian studies, prevalence of GERD ranges from 2.5% to 7.8% and 11.6% in Australia.6
Studies between 1992 and 2011 suggest that the prevalence of GERD may be increasing worldwide, but remains lowest in East Asia and highest in Western countries.5
Risk Factors and Associated Conditions
Risk factors for the development of GERD include obesity, increasing age, and genetics (concordance rates are higher in monozygotic vs dizygotic twins). Behavioral factors may include alcohol consumption, tobacco use, and diet.5
The prevalence of GERD does not increase with age, but symptom intensity may decrease after age 50.7 Prevalence of erosive esophagitis, however, does increase with age over 50.8
GERD is frequently associated with pregnancy, often presenting as heartburn. While onset can occur at any point during a pregnancy, the majority of cases begin in the first trimester (52%), with decreasing frequency of onset later in pregnancy (40% in the second trimester, 8% in the third trimester).9 Overall prevalence of symptoms, however, increases throughout pregnancy, with up to 72% of pregnant patients reporting heartburn symptoms in the third trimester. Symptom severity also increases as pregnancy progresses.10
Normal Lower Esophageal Sphincter Anatomy/Physiology
The lower esophageal sphincter (LES) is a physiologic high-pressure zone located just cephalad to the gastroesophageal junction (GEJ), which serves to prevent retrograde passage of gastric contents into the esophagus. The antireflux mechanism is supported by the lower esophageal musculature, interaction with the diaphragmatic hiatus, ...