Seasonal Variation in Emergency General Surgery.

Abstract

The aim of this study was to assess the seasonal variation in emergency general surgery (EGS) admissions. Seasonal variation in medical conditions is well established; however, its impact on EGS cases remains unclear. 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. 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). 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.