What is the incidence of acute appendicitis?

Incidence of Acute Appendicitis

The incidence of acute appendicitis in developed countries occurs at a rate of 5.7-50 patients per 100,000 inhabitants per year, with a peak between the ages of 10 and 30 years. 1

Global Epidemiology

• The annual incidence of acute appendicitis is approximately 86-100 per 100,000 population per year, making it one of the most common causes of acute abdominal pain requiring emergency intervention 2, 3
• Geographical differences exist in the lifetime risk for acute appendicitis: 9% in the USA, 8% in Europe, and 2% in Africa 1
• The incidence has been declining steadily since the late 1940s, though some longitudinal studies suggest stability in incidence over 10-year observation periods 4
• Appendicitis is the most common abdominal surgical emergency worldwide and accounts for 34.2% of cases of intra-abdominal sepsis 5

Age and Sex Distribution

• The highest incidence of nonperforated appendicitis occurs among adolescents and young adults (13-40 years of age) 3
• After adolescence, the incidence of acute appendicitis decreases with increasing age 1
• Among patients presenting with acute abdominal pain in the Emergency Department, approximately 15% of patients older than 50 years will have a final diagnosis of acute appendicitis, compared to nearly 30% of younger patients 1
• The lifetime risk is slightly higher in males (8.6%) compared to females (6.7%) 6

Complicated vs. Uncomplicated Appendicitis

• Perforated appendicitis occurs at almost the same incidence across all sex and age groups, unlike nonperforated appendicitis which peaks in younger populations 3
• The rate of perforation varies from 16% to 40%, with higher frequencies in younger age groups (40-57%) and in patients older than 50 years (55-70%) 1
• Elderly patients (>65 years) have significantly higher rates of complicated appendicitis with perforation or abscess, ranging from 18% to 70%, compared to 3-29% among younger patients 1
• The presence of an appendicolith is strongly associated with progression to complicated disease 5

Mortality Considerations

• Mortality risk varies significantly by disease severity:
  • Acute but not gangrenous appendicitis: less than 0.1% 1
  • Gangrenous appendicitis: 0.6% 1
  • Perforated appendicitis: approximately 5% 1
• In elderly patients, appendicitis is associated with significantly higher mortality, reaching 8% among patients older than 65 years 1
• The case fatality rate after appendectomy increases threefold with each decade of age beyond 65 years, reaching more than 16% in nonagenarians 1

Clinical Implications

• Delayed diagnosis is common in elderly patients, contributing to higher perforation rates and poorer outcomes 1
• Elderly patients experience higher post-operative mortality, higher post-operative morbidity, longer hospital stays, and often require more complex surgical procedures compared to younger patients 1
• The diagnostic accuracy is lower in both very young children and elderly patients, contributing to higher perforation rates in these populations 3

Understanding the incidence patterns of acute appendicitis is crucial for appropriate resource allocation in emergency departments and for developing age-appropriate diagnostic and treatment algorithms that can reduce morbidity and mortality, particularly in high-risk populations such as the elderly.