title: Short and long-term mortality after appendectomy in Sweden 1987 to 2006. Influence of appendectomy diagnosis, sex, age, co-morbidity, surgical method, hospital volume, and time period. A national population-based cohort study.
abstract: BACKGROUND
  Avoiding mortality is the ultimate goal when managing patients with suspected appendicitis. Previous studies have shown high mortality after negative appendectomy. This national cohort study analyzes short- and long-term mortality after appendectomy in relation to appendectomy diagnosis, age, co-morbidity, surgical method, hospital volume, and time period.
  
  
  METHODS
  A total of 223,543 appendectomy patients treated from 1987 to 2006 were identified from the Swedish National Patient Register and followed up via the Swedish Cause of Death Register. Analysis of mortality was conducted as Standardized Mortality Ratio (SMR) and by Cox multivariate regression.
  
  
  RESULTS
  Negative appendectomy was followed by a higher mortality in the short term (30-day Standardized Mortality Ratio (SMR30d) 8.95, confidence interval (CI) 6.68-12.61) than after perforated appendicitis (SMR30d 6.39, CI 5.44-7.48), and remained increased for up to 5 years (SMR5yr 1.31, CI 1.16-1.47). Non-perforated appendicitis had a lower than expected long-term mortality (SMR5yr 0.72, CI 0.68-0.76). These differences remained after adjustment for covariates. Laparoscopic appendectomy had similar short-term mortality as open appendectomy but lower than expected long-term morality (SMR5yr 0.70, CI 0.62-0.78). Mortality was decreasing during the study period. Hospital volume had no influence on mortality.
  
  
  CONCLUSIONS
  Negative appendectomy is associated with excess short- and long-term mortality that remains after adjustment for known confounders, suggesting an association with underlying undetected morbidity. This motivates an improved preoperative diagnosis to avoid the additional trauma from unnecessary surgical interventions, but further studies are needed to investigate the cause of the increased long-term mortality and if this can be prevented by an improved follow-up of patients with negative appendectomy. Laparoscopic and open appendectomy have similar short-term mortality. The lower long-term mortality after non-perforated appendicitis and laparoscopic appendectomy suggest selection of healthier patients for these interventions. This possibility should be taken into account when comparing mortality after open and laparoscopic appendectomy.
authors.affiliation: Department of Surgery, Ryhov County Hospital, SE-551 85 Jönköping, Sweden. roland.andersson@lj.se
authors.forename: Roland E
authors.initials: RE
authors.lastname: Andersson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy / Q000379:methods / Q000401:mortality*; D001064:Appendicitis / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D061847:Hospitals, High-Volume / Q000706:statistics & numerical data; D061846:Hospitals, Low-Volume / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D010535:Laparoscopy / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012042:Registries; D013548:Sweden / Q000453:epidemiology; D016896:Treatment Outcome; D019564:Unnecessary Procedures / Q000401:mortality; D055815:Young Adult