Meteorological and demographic factors associated with the onset of acute appendicitis in rural islands of Japan.

Introduction: Emergency surgery and hospitalisation has become a burden in rural areas owing to a shortage of surgeons. Acute appendicitis is a common emergency disease. Understanding the aetiology of acute appendicitis could predict emergency surgeries to optimise resource allocation in rural areas. Several studies have pointed out that some meteorological factors are associated with acute appendicitis; however, there is no consensus about these factors. With the geographical advantages, homogenous meteorological effects, and overwhelming medical data collection in the area, this study aimed to explore meteorological and demographic factors associated with acute appendicitis by focusing on the onset day of acute appendicitis. Methods: Miyako islands is in southern Japan and it has a subtropical climate. Okinawa Miyako prefectural Hospital (OMH) is the only hospital in the area that conducts emergency surgery. A total of 212 acute appendectomy cases collected over 6 years were analysed for sex, age, onset date, pathology type, perforation, and fecaliths. Meteorological factors (air pressure, air temperature, humidity, precipitation, wind speed, sunlight hours, and lunar age) on the onset day of acute appendicitis were analysed. Results: Significant differences between air temperature 6 and 7 days before onset and the onset day were observed. Higher air temperature, compared to the average value, was significant in acute appendicitis cases. Pathological types were associated with age group, perforation, and fecaliths. Age group was also associated with existing perforation. Discussion: Increase in temperature throughout the week prior to onset could be an anticipating factor for the onset of acute appendicitis. Conclusion: The meteorological and demographic features associated with the onset of acute appendicitis could become keys to evaluating acute appendicitis risk in the future and contribute to reasonable allocation of scarce surgical resources to rural areas.