title: Routine interval appendectomy is not justified after initial nonoperative treatment of acute appendicitis.
abstract: BACKGROUND
  The role of interval appendectomy (IA) after an episode of acute appendicitis is debated.
  
  
  OBJECTIVE
  Patients treated nonoperatively for acute appendicitis do not require routine IA.
  
  
  METHODS
  Retrospective cohort study using discharge abstract data.
  
  
  METHODS
  Twelve regional Kaiser Permanente hospitals in Southern California.
  
  
  METHODS
  A total of 32 938 patients were hospitalized with acute appendicitis.
  
  
  METHODS
  Appendectomy or nonoperative treatment with or without abscess drainage.
  
  
  METHODS
  Hospitalization for recurrent appendicitis or IA.
  
  
  RESULTS
  The type of appendicitis was abscess in 7% of patients, peritonitis in 18%, and no peritonitis or abscess in 75%. Emergency appendectomy was performed in 31 926 (97%) patients. Nonoperative treatment was used initially in 1012 patients (3%). Of these, 148 (15%) had an IA and the remaining 864 (85%) did not. Thirty-nine patients (5%) recurred after a median follow-up of 4 years. Using Cox regression, sex had a slight influence on recurrent appendicitis (hazard ratio males vs females = 0.52, 95% CI, 0.27-0.99, P = .05). Age, Charlson comorbidity index, type of appendicitis, or percutaneous abscess drainage had no influence on recurrence. Median length of hospital stay was 4 days for the admission for recurrent appendicitis compared with 6 days for the IA admission (P = .006).
  
  
  CONCLUSIONS
  Most patients with acute appendicitis undergo appendectomy initially. For those treated nonoperatively, the recurrence rate is low. Routine IA after initial successful nonoperative treatment is not justified and should be abandoned.
authors.affiliation: Department of Surgery, Kaiser Permanente Los Angeles Medical Center, CA 90027, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Kaminski
authors.forename: In-Lu Amy
authors.initials: IL
authors.lastname: Liu
authors.forename: Harry
authors.initials: H
authors.lastname: Applebaum
authors.forename: Steven L
authors.initials: SL
authors.lastname: Lee
authors.forename: Philip I
authors.initials: PI
authors.lastname: Haigh
mesh_terms: D018784:Abdominal Abscess / Q000209:etiology / Q000628:therapy*; D000208:Acute Disease; D000328:Adult; D001062:Appendectomy; D001064:Appendicitis / Q000150:complications / Q000601:surgery*; D015331:Cohort Studies; D004322:Drainage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010538:Peritonitis / Q000209:etiology / Q000628:therapy*; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors