title: Incidence of appendicitis according to region of origin in first- and second-generation immigrants and adoptees in Sweden. A cohort follow-up study.
abstract: BACKGROUND
  Geographic variations in incidence of appendicitis and proportion of perforations suggest environmental or genetic etiological factors. We study incidence of appendicitis and proportion of perforations according to geographical origin in immigrants and international adoptees in Sweden.
  
  
  METHODS
  A cohort of 11,557,566 Swedish residents - 277,104 first- and 377,773 second-generation immigrants and 57,304 adoptees - was followed from 1988 till 2010. Differences in proportion of operation for perforated appendicitis and negative appendectomy and standardized incidence ratios (SIR) of perforated and non-perforated appendicitis associated with geographic origin was analyzed.
  
  
  RESULTS
  High incidence rates are seen in first- and second-generation immigrants from South America for perforated (SIR 1.58 and 1.81, respectively) and non-perforated appendicitis (SIR 1.18 and 1.22, respectively), and in adoptees from South America for non-perforated appendicitis (SIR 1.07). Low incidence rates are seen for perforated appendicitis in first-generation immigrants and adoptees from Asia (SIR 0.74 and 0.56, respectively), and for non-perforated appendicitis in immigrants from Africa and Asia (SIR 0.69 and 0.76 in first-generation, 0.51 and 0.74 in second-generation, respectively) and in adoptees from Asia (SIR 0.71). A high proportion of perforated appendicitis is associated with a low incidence rate of non-perforated appendicitis but no increase in the incidence rate of perforated appendicitis.
  
  
  CONCLUSIONS
  The association of different incidence of appendicitis with geographic origin which remains over generations and is seen in adoptees suggest genetic etiologic factors. The proportion of perforation can be high without an increased incidence rate of perforation and is therefore an imperfect indicator of quality of care.
authors: a 1 Departments of Pediatrics, County Hospital Ryhov , Jönköping, Sweden.
authors: John
authors: J
authors: Terlinder
authors: b 2 Departments of Surgery, County Hospital Ryhov , Jönköping, Sweden.
authors: Roland E
authors: RE
authors: Andersson
mesh_terms: D000300:Adoption; D001064:Appendicitis / Q000208:ethnology*; D044466:Asian People; D044383:Black People; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D012042:Registries; D012307:Risk Factors; D013020:South America / Q000208:ethnology; D013548:Sweden / Q000453:epidemiology
keywords: appendicitis; epidemiology; migration; perforation rate