Seasonal variations of acute appendicitis and nonspecific abdominal pain in Finland.
OBJECTIVE
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.


CONCLUSIONS
The incidence of acute appendicitis is declining in Finland. We detected a clear seasonality in the incidence of AA and NSAP.
Imre Ilves, Anne Fagerström, Petri Juvonen, Pekka Miettinen, Hannu Paajanen, Department of Surgery, Kuopio University Hospital, FI-70211 Kuopio, Finland.
Imre
I
Ilves
Imre Ilves, Anne Fagerström, Petri Juvonen, Pekka Miettinen, Hannu Paajanen, Department of Surgery, Kuopio University Hospital, FI-70211 Kuopio, Finland.
Anne
A
Fagerström
Imre Ilves, Anne Fagerström, Petri Juvonen, Pekka Miettinen, Hannu Paajanen, Department of Surgery, Kuopio University Hospital, FI-70211 Kuopio, Finland.
Karl-Heinz
KH
Herzig
Imre Ilves, Anne Fagerström, Petri Juvonen, Pekka Miettinen, Hannu Paajanen, Department of Surgery, Kuopio University Hospital, FI-70211 Kuopio, Finland.
Petri
P
Juvonen
Imre Ilves, Anne Fagerström, Petri Juvonen, Pekka Miettinen, Hannu Paajanen, Department of Surgery, Kuopio University Hospital, FI-70211 Kuopio, Finland.
Pekka
P
Miettinen
Imre Ilves, Anne Fagerström, Petri Juvonen, Pekka Miettinen, Hannu Paajanen, Department of Surgery, Kuopio University Hospital, FI-70211 Kuopio, Finland.
Hannu
H
Paajanen
D015746:Abdominal Pain / Q000175:diagnosis* / Q000453:epidemiology; D000208:Acute Disease; D001062:Appendectomy / Q000706:statistics & numerical data; D001064:Appendicitis / Q000175:diagnosis* / Q000453:epidemiology; D002980:Climate; D005387:Finland / Q000453:epidemiology; D005843:Geography; D006801:Humans; D006813:Humidity; D015994:Incidence; D012042:Registries; D012044:Regression Analysis; D012621:Seasons; D013696:Temperature
Acute appendicitis; Appendectomy; Humidity; Incidence; Nonspecific abdominal pain; Seasonal; Temperature