Seasonal variations of acute appendicitis and nonspecific abdominal pain in Finland

Abstract

Aim: To investigate whether seasonal changes had an effect on the incidence of acute appendicitis (AA) or nonspecific abdominal pain (NSAP).

Methods: We carried out a national register study of all patients with a hospital discharge diagnosis of AA and acute NSAP in Finland. Data were analyzed for the whole country and correlated to seasonal and weather parameters (temperature, humidity). Moreover, additional sub-analyses were performed for five geographically different area of Finland.

Results: The observation period spanned 21 years, with 186558 appendectomies, of which 137528 (74%) cases were reported as AA. The incidence of AA declined for 32% over the study period. The average incidence of the NSAP was 34/10000 per year. The mean annual temperature, but not relative humidity, showed clear geographical variations. The incidence of AA decreased significantly during the cold months of the year. No correlation was detected between temperature and incidence of NSAP. Humidity had a statistically significant impact on NSAP.

Conclusion: The incidence of acute appendicitis is declining in Finland. We detected a clear seasonality in the incidence of AA and NSAP.

Keywords: Acute appendicitis; Appendectomy; Humidity; Incidence; Nonspecific abdominal pain; Seasonal; Temperature.

Figures

Figure 1

Temperature, humidity and incidences of acute appendicitis, and non-specific abdominal pain in 1987-2007 in Finland. AA: Acute appendicitis; NSAP: Non-specific abdominal pain.

Figure 2

Acute appendicitis, non-specific abdominal pain, temperature and humidity in Finland (as mean value over the 21 years). AA: Acute appendicitis; NSAP: Non-specific abdominal pain.

Figure 3

University hospital districts of Finland. Areas: I: UHD of Helsinki; II: UHD of Turku; III: UHD of Tampere; IV: UHD of Oulu; V: UHD of Kuopio. UHD: University hospital districts of Finland.

Figure 4

Incidences of acute appendicitis and non-specific abdominal pain during the warm compared to the cold periods of the year in Finland. AA: Acute appendicitis; NSAP: Non-specific abdominal pain.