Association between climatic elements and acute appendicitis in Japan

Abstract Background In Japan, it has been reported that an increase in atmospheric pressure is associated with a higher incidence of acute appendicitis. The aim of this epidemiologic study was to investigate the association between climatic elements and the incidence of acute appendicitis. Materials and methods A case-crossover design was used in the present study. Two wk before diagnosis was used for the target period. The same 2-wk period, but 1, 2, and 3 y before diagnosis, was used for the control period. The study participants were patients with acute appendicitis (10-29 y) from 14 facilities in the Greater Tokyo Area. Mean of the observed values for atmospheric pressure, temperature, relative humidity, and hours of sunshine calculated for each target and control period were used as climatic elements to investigate trends 1 and 2 wk before diagnosis. Results The year of diagnosis, a statistically significant moderate upward trend in atmospheric pressure was observed during the 2-wk period before diagnosis of acute appendicitis (tau = 0.47; P  = 0.0213), whereas a weak nonsignificant downward trend was observed 1 y before diagnosis (tau = −0.29; P  = 0.1596), and weak nonsignificant upward trends were observed 2 (tau = 0.24; P  = 0.2505) and 3 y (tau = 0.28; P  = 0.1634) before diagnosis. Conclusions An association was found between atmospheric pressure and the incidence of acute appendicitis. However, no significant differences were found in relation to sex or age. These findings suggest that changes in atmospheric pressure are associated with the likelihood of patients visiting the hospital.