What is the risk of appendicitis by age group?

Risk of Appendicitis by Age

Appendicitis is most common in children and young adults with peak incidence between ages 10-30 years, but the disease becomes dramatically more dangerous with advancing age, particularly after 65 years when mortality increases threefold with each decade. 1, 2

Incidence Patterns Across Age Groups

Peak Incidence: Young Adults and Adolescents

• The highest incidence occurs between ages 10-19 years, with overall rates of 5.7-50 per 100,000 inhabitants per year in developed countries 2, 3
• After adolescence, the incidence progressively decreases with increasing age 2
• The lifetime risk varies geographically: 9% in the USA, 8% in Europe, and 2% in Africa 2
• Among patients presenting with acute abdominal pain in the Emergency Department, approximately 30% of younger patients will have appendicitis compared to only 15% of patients older than 50 years 2

Pediatric Considerations

• Appendicitis is uncommon in infants and preschool children, and rare in newborns, despite being the most common abdominal surgical emergency overall in the pediatric population 4
• Children under 5 years, particularly around age 4, present with atypical symptoms significantly more frequently than older children, leading to higher rates of delayed diagnosis and perforation 4

Middle-Aged Adults (30-64 years)

• This age group constitutes approximately 45% of all appendicitis cases, similar to the proportion seen in young adults (≤29 years) 5
• Resource utilization, length of stay, and hospital charges begin to increase in this age bracket 5

Elderly Population (≥65 years)

• While the incidence of appendicitis decreases in elderly patients, the disease burden is dramatically higher 1
• Recent data suggests the proportion of elderly patients with appendicitis is increasing, from 0.93% in 2007 to 4.28% in 2016 6
• Elderly patients (≥80 years) represent a substantial and growing population requiring appendectomy 5

Age-Related Mortality and Morbidity

Mortality Risk by Age

• Mortality in patients younger than 65 years ranges from 0-1% 1
• Mortality reaches 8% among patients older than 65 years 1, 2
• The case fatality rate after appendectomy increases threefold with each decade of age beyond 65 years, reaching more than 16% in nonagenarians 1, 2
• Age older than 65 was identified as a significant independent risk factor for mortality in a large observational study of 164,579 patients 1

Perforation Rates by Age

• Younger patients (<65 years): 3-29% perforation rate 1
• Elderly patients (>65 years): 18-70% perforation rate 1, 2
• Young children also have elevated perforation rates (40-57%) due to delayed diagnosis 2
• Patients older than 50 years have perforation rates of 55-70% 2

Pathophysiologic Differences in Elderly Patients

Anatomic Changes with Aging

• The vermiform appendix develops vascular sclerosis in elderly patients, with narrowing of the lumen by fibrosis 1, 2
• Muscular layers become infiltrated with fat, creating structural weakness with tendency toward early perforation 1, 2
• These anatomic changes, combined with delayed diagnosis and treatment, explain the more aggressive disease course in this population 1

Diagnostic Challenges in the Elderly

• Diagnostic accuracy is only 64% in patients over 65 years compared to 78% in younger age groups (p < 0.01) 1
• Average time from symptom onset to admission and from admission to surgery is significantly greater in older patients 1
• Elderly patients have higher rates of atypical presentations, with comorbidities and concurrent medications further complicating diagnosis 1

Surgical Outcomes by Age

Elderly-Specific Complications

• Higher post-operative mortality compared to young patients 1, 2
• Higher post-operative morbidity 1, 2
• Longer length of hospital stay 1
• Longer operative time 1
• Lower laparoscopic appendectomy rates despite similar eligibility 1
• Higher risk of requiring more complex surgical procedures 1
• Complication rate with negative appendectomy: 25% in elderly vs 3% in younger patients (p < 0.05) 1

Clinical Implications

Maintain a high index of suspicion for appendicitis in elderly patients despite lower overall incidence, as delayed diagnosis carries catastrophic consequences. The combination of atypical presentations, diagnostic delays, and age-related anatomic changes creates a perfect storm for complicated disease in this population 1. Early imaging and aggressive management are essential to reduce the dramatically elevated mortality risk that increases exponentially with each decade beyond age 65 1, 2.