Introduction
Dyspepsia_Disease BackgroundDyspepsia refers to the pain or discomfort centered in the upper abdomen. The discomfort refers to a subjective sensation that the patient does not interpret as pain, which may be characterized by or associated with upper abdominal fullness, early satiety, epigastric burning, bloating, belching, or nausea and vomiting (N/V). Centered refers to the pain or discomfort in or around the midline. Dyspepsia is commonly referred to as indigestion and it is considered a symptom complex rather than a specific diagnosis.
Uninvestigated dyspepsia refers to dyspeptic symptoms in individuals who have not yet undergone diagnostic investigations and in whom no specific diagnosis explaining these symptoms has been established.
Epidemiology
Functional Dyspepsia or Non-Ulcer Dyspepsia
The global prevalence of functional dyspepsia is 5-11%, with the prevalence of uninvestigated dyspepsia and functional dyspepsia at 5-30% in Asian countries. The lowest prevalence rate was found in Japan and high prevalence rates were found in Egypt, Brazil, Russia and the USA. This is more common in women than men, in smokers and nonsteroidal anti-inflammatory drugs (NSAIDs) users. Based on several studies, the prevalence of functional dyspepsia declines with increasing age and is highest among younger adults. This commonly overlaps with other disorders of gut-brain interaction (DGBIs) (eg IBS and functional heartburn) and with GERD.
Etiology
Peptic ulcer disease and gastroesophageal reflux disease (GERD) are the predominant identifiable etiologies of dyspeptic symptoms. Although less prevalent, upper gastrointestinal malignancies and celiac disease represent important organic causes. Dyspepsia-like symptoms may arise from various gastrointestinal disorders, including infectious, inflammatory, and infiltrative diseases affecting the upper gastrointestinal tract.
Dyspepsia is a frequent adverse effect of numerous medications and these effects may arise from gastric mucosal injury, altered gastrointestinal motility or sensation, increased gastroesophageal reflux, or idiosyncratic reactions. Nonsteroidal anti-inflammatory drugs have been most extensively studied due to their potential to cause gastrointestinal ulceration. Chronic use of aspirin and other NSAIDs may lead to dyspeptic symptoms.
Pathophysiology
Functional Dyspepsia or Non-Ulcer Dyspepsia
The pathophysiology is multifactorial, and local factors (eg prevalence of GI malignancy and Asian dietary habits) must be considered. The microscopic physiologic mechanisms of functional dyspepsia include barrier function impairment from altered sensitivity to duodenal acid or lipids that impair mucosal integrity, low-grade gastroduodenal inflammation, gut microbiome alteration and H pylori infection. The macroscopic physiological mechanisms include GERD, stomach morphology, impaired gastric accommodation, delayed or rapid gastric emptying, gastric dysrhythmias, antral hypomotility, and visceral hypersensitivity alterations in the nervous system. Other factors that may have a role in the development of functional dyspepsia include anxiety, depression, sleep disturbance, stress, history of abuse, family history and genetic factors, demographic factors (female sex, BMI, socioeconomic status), lifestyle (eg smoking and alcohol consumption) and dietary practices (fat-rich meals, restrictive eating).