title: Seasonal Variation in Emergency General Surgery.
abstract: OBJECTIVE
  The aim of this study was to assess the seasonal variation in emergency general surgery (EGS) admissions.
  
  
  BACKGROUND
  Seasonal variation in medical conditions is well established; however, its impact on EGS cases remains unclear.
  
  
  METHODS
  The National Inpatient Sample (NIS) database was queried over an 8-year period (2004-2011) for all patients with diagnosis of acute appendicitis, acute cholecystitis, and diverticulitis. Elective admissions were excluded. The following data for each admission were recorded: age, sex, race, admission month, major operative procedure, hospital region, and mortality. Seasons were defined as follows: Spring (March, April, May), Summer (June, July, August), Fall (September, October, November), and Winter (December, January, February). X11 procedure and spectral analysis were performed to confirm seasonal variation.
  
  
  RESULTS
  A total of 63,911,033 admission records were evaluated of which 493,569 were appendicitis, 395,838 were cholecystitis, and 412,163 were diverticulitis. Seasonal variation is confirmed in EGS (F = 159.12, P < 0.0001) admissions. In the subanalysis, seasonal variation was found in acute appendicitis (F = 119.62, P < 0.0001), acute cholecystitis (F = 37.13, P < 0.0001), and diverticulitis (F = 69.90, P < 0.0001). The average monthly EGS admission in Winter was 11,322 ± 674. The average monthly EGS admission in Summer was higher than that of Winter by 13.6% (n = 1542; 95% CI: 1180-1904, P < 0.001).
  
  
  CONCLUSIONS
  Hospitalization due to EGS adheres to a consistent cyclical pattern, with more admissions occurring during the Summer months. Although the reasons for this variability are unknown, this information may be useful for hospital resource reallocation and staffing.
authors: Division of Trauma, Department of Surgery, University of Arizona, Tucson, AZ.
authors: Bardiya
authors: B
authors: Zangbar
authors: Peter
authors: P
authors: Rhee
authors: Viraj
authors: V
authors: Pandit
authors: Chiu-Hsieh
authors: CH
authors: Hsu
authors: Mazhar
authors: M
authors: Khalil
authors: Terence
authors: T
authors: Okeefe
authors: Leigh
authors: L
authors: Neumayer
authors: Bellal
authors: B
authors: Joseph
mesh_terms: D000208:Acute Disease; D000328:Adult; D001064:Appendicitis / Q000453:epidemiology / Q000601:surgery*; D002764:Cholecystitis / Q000453:epidemiology / Q000601:surgery*; D004238:Diverticulitis / Q000453:epidemiology / Q000601:surgery*; D004638:Emergency Treatment / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D012621:Seasons; D013514:Surgical Procedures, Operative / Q000706:statistics & numerical data*