title: Changing roles of computed tomography in diagnosing acute appendicitis in emergency rooms.
abstract: BACKGROUND
  We used the Taiwan National Health Insurance Database for analysis and statistics to investigate the role of computed tomography (CT) in diagnosing acute appendicitis.
  
  
  METHODS
  All 10 046 patients with acute appendicitis were selected and categorized into two groups based on those who did and did not receive CT 3 days before acute appendicitis diagnosis: non-CT and CT groups. A noteworthy outcome was the incidence of peritonitis within 90 days after diagnosis of acute appendicitis.
  
  
  RESULTS
  The rate of using CT for patients with acute appendicitis increased considerably from 7.9% to 52.9% from 2000 to 2010. The peritonitis incidence rates were 3.54% and 10.7% in the non-CT and CT groups, respectively. Patients who received CT on the same day exhibited a 3.8-fold higher risk of peritonitis than did those in the non-CT group. Those who underwent CT before diagnosis of acute appendicitis exhibited no significant difference of peritonitis risk when compared with those in the non-CT group. The CT group patients were hospitalized 2.19 days longer than the non-CT group patients. Patients who received CT before and on the same day were hospitalized 1.31 and 2.43 days longer than those who did not undergo CT.
  
  
  CONCLUSIONS
  Patients who underwent CT exhibited higher risks of peritonitis and longer hospital stays compared with those who did not. Moreover, patients who received CT on the same day of operation exhibited a higher risk of peritonitis than those who underwent CT 1 or 2 days before operation.
authors.affiliation: From the Department of Radiology, China Medical University Hospital, Taichung, Taiwan, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: T-L
authors.initials: TL
authors.lastname: Ho
authors.affiliation: Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan, College of Medicine.
authors.forename: C-H
authors.initials: CH
authors.lastname: Muo
authors.affiliation: From the Department of Radiology, China Medical University Hospital, Taichung, Taiwan, Department of Biomedical Imaging and Radiological Science, College of Health Care.
authors.forename: W-C
authors.initials: WC
authors.lastname: Shen
authors.affiliation: Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan and Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan d10040@mail.cmuh.org.tw.
authors.forename: C-H
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D001064:Appendicitis / Q000150:complications / Q000000981:diagnostic imaging* / Q000453:epidemiology; D002648:Child; D016208:Databases, Factual; D004630:Emergencies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data / Q000639:trends; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010538:Peritonitis / Q000453:epidemiology / Q000209:etiology; D018570:Risk Assessment / Q000379:methods; D013624:Taiwan / Q000453:epidemiology; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000706:statistics & numerical data* / Q000639:trends