Epidemiologic features, seasonal variations and false positive rate of acute appendicitis in Shahr-e-Rey, Tehran

Introduction: Appendicitis is the most common acute surgical condition of the abdomen. Age, sex and seasonal variations have been observed in many studies. To describe and find the possible differences in the epidemiology of acute appendicitis in Shahr-e-Rey, we carried out a retrospective study of all patients with acute appendicitis admitted to Shohadaay-e Haftom-e Tir hospital as it is the only hospital in this restricted part of Tehran. Methods: Using hospital discharge abstract of patients who were admitted with the diagnosis of acute appendicitis from summer 1996 to spring 2004, we studied the demographic features, particularly age and sex, date of admission and final diagnosis of these patients. Results: During the observation period, 1093 cases were admitted with the diagnosis of acute appendicitis. Of these, 74.4% were males and 6.1% were not actually an acute appendicitis. The age-specific incidence of acute appendicitis has different patterns in male and female. The incidence was highest in males aged 20-29 years whereas in females the highest incidence was observed in 10-19 years age group. A significant seasonal effect was also observed, with the rate of acute appendicitis higher in the summer months (p < 0.006). The rate of false positive diagnosis was highest in the patients aged 0-9 years (p < 0.0001). Of those correctly diagnosed, 85.5% had uncomplicated acute appendicitis; 8.3% had perforation; and others (6.2%) had acute appendicitis complicated with other situations. Conclusion: Appendicitis is more common in males, in those aged 20-29 years, and during the summer months. The age-specific incidence and sex ratio of acute appendicitis give the impression that epidemiologic features of acute appendicitis are different with worldwide data. However, the seasonal variation and false positive rate of acute appendicitis are in a good agreement with other studies.