Stability in incidence of acute appendicitis. A population-based longitudinal study

BACKGROUND/AIM OF THE STUDY: During the past 50 years, a decrease in incidence of appendicitis has been reported. The various studies were retrospective and based on different data sources. In the present study, we analyze prospectively the incidence of acute appendicitis during a 10-year period in a well defined population of 265,000. Prospective registration of all operations performed in patients with suspected acute appendicitis in the catchment area of a single institution. The diagnosis of acute appendicitis was based on histology in all cases. The annual incidence of acute appendicitis was calculated with regard to nonperforated and perforated acute appendicitis. Between 1989 and 1998, 2,861 patients underwent surgery for suspected acute appendicitis. In 2,232 (78%) patients, acute appendicitis was confirmed histologically. Mean annual incidence was 84/100,000 (95% confidence interval 80 to 88/100,000). Crude incidence remained stable during the study period, with the exception of a significant increase in 1991 followed by a significant decrease the next year. Nonperforated acute appendicitis showed a different incidence pattern as compared to perforated acute appendicitis. In our prospective study, the incidence of acute appendicitis remained stable in our well-defined study population during the study period of 10 years. This is in contrast to the majority of studies during the last decades.