Changing Incidence of Acute Appendicitis and Nonspecific Abdominal Pain Between 1987 and 2007 in Finland

Background The incidence of acute appendicitis has declined in many countries. The aim of this study was to determine the trends in incidence of acute appendicitis (AA), appendectomies for AA, and nonspecific abdominal pain (NSAP) in Finland between 1987 and 2007. Methods We carried out a national register study. Demographic features were investigated. Diagnoses and procedures were classified according to the World Health Organization International Classification of Diseases. Data were analyzed for each of all five University Hospital districts (UHD) of Finland. Results During the observation period of 21 years, 186,558 appendectomies were performed in Finland, of which 137,528 (74%) cases were reported as AA. The incidence of acute appendicitis declined 32%. The diagnostic accuracy improved from 73 to 82% and was higher in men. The accuracy rate among the male patients was stable throughout the two decades; among the female patients it rose from 63 to 75%. The incidence of appendicitis was highest in patients aged 15-24 years. The average incidence of NSAP was 34/10,000/year, and it was higher in older age groups. There was a large geographical disparity in the incidence of NSAP. Conclusion The incidence of acute appendicitis as well as the incidence of appendectomies is declining in Finland. The incidence of the NSAP has also been declining but we did not find any correlations between the incidences of the acute appendicitis and NSAP. There were clear geographical differences in the incidence of NSAP but not in the incidence of AA.