What is Acid Reflux (GERD)?
Gastroesophageal reflux disease (GERD) is defined as chronic symptoms or mucosal damage produced by the abnormal reflux of gastric contents into the esophagus, distinguished from normal physiologic reflux by the presence of troublesome symptoms and/or tissue damage. 1
Distinguishing Normal Reflux from Disease
Gastroesophageal reflux (GER) is a normal physiologic process that occurs up to 50 times daily in healthy individuals, typically during meals and the postprandial state, without producing symptoms. 1 In contrast, GERD represents a pathologic condition where this reflux causes either troublesome symptoms or tissue damage that affects quality of life. 1
The key distinction is that GERD is a disease manifested by either symptoms and/or tissue damage, whereas GER events can be entirely physiologic in nature. 1
Primary Clinical Manifestations
Typical Esophageal Symptoms
Heartburn is the most commonly recognized manifestation, described as a substernal burning sensation in the chest that moves upward toward the throat, occurring in approximately 89% of gastroenterology patients. 1, 2
Acid regurgitation involves the backflow of gastric contents into the esophagus or mouth and represents another cardinal symptom. 2
These typical symptoms (heartburn and regurgitation) are approximately 70% sensitive and specific for objective GERD, providing the rationale for empiric proton pump inhibitor trials without prior testing. 2
Extraesophageal and Atypical Presentations
A critical clinical pitfall is that GERD can be completely silent from a gastrointestinal standpoint in up to 75% of patients when it causes chronic cough. 1, 2 This makes diagnosis particularly challenging in patients presenting with respiratory or laryngeal symptoms.
Chronic cough accounts for 5-41% of chronic cough cases in adults. 2
Hoarseness is present in 100% of otolaryngology patients with laryngopharyngeal reflux disease, yet only 6% report heartburn. 2
Other atypical manifestations include dysphagia, chest pain, and various respiratory symptoms. 1
Epidemiology and Prevalence
GERD is ubiquitous in industrialized nations, with substantial variation in symptom frequency:
44% of adults in the United States experience heartburn at least once monthly. 1
18-20% of respondents experience heartburn or reflux symptoms at least weekly. 1
Population studies show a 59% prevalence of occasional GER-related symptoms including heartburn, regurgitation, and dysphagia. 2
The prevalence is notably lower in Eastern Asia (8.5%) compared to Western Europe and North America (10-20%). 1
Potential Complications
Previously regarded as a nuisance problem, GERD is now recognized to have potentially serious complications that impact morbidity and mortality:
Erosive esophagitis develops from chronic acid exposure. 1
Peptic strictures can cause progressive dysphagia. 1
Barrett esophagus represents a metaplastic change from normal squamous epithelium to specialized columnar lining, serving as a precursor lesion to esophageal adenocarcinoma. 1
Esophageal adenocarcinoma has increased 300-500% over the past 30-40 years, though the absolute risk in any individual with GERD remains low. 1
Pulmonary complications including recurrent pneumonia and chronic respiratory disease can occur from aspiration. 2
Age-Specific Considerations
Infants
Regurgitation or "spitting up" occurs daily in 50% of all infants as a normal physiologic process, with peak incidence at 4 months of age, declining to affect only 5-10% of infants at 12 months. 1 Common GERD symptoms in infants include regurgitation associated with irritability, feeding refusal, poor weight gain, and back arching during feedings. 1
Children and Adolescents
Heartburn and regurgitation present similarly to adults. 1 High-risk pediatric populations include those with neurologic impairment, obesity, history of repaired esophageal atresia, and chronic respiratory disorders. 1
Pathophysiology
The defining pathologic feature is that most asymptomatic individuals experience several episodes of undetected acid reflux daily, but GERD occurs when this reflux becomes abnormal in frequency, duration, or severity, producing chronic symptoms or mucosal damage. 1 The primary mechanism involves transient relaxations of the lower esophageal sphincter independent of swallowing, permitting gastric contents to enter the esophagus. 1