title: Frequency of Cholelithiasis and Biliary Pathology in the Easter Island Rapanui and Non-Rapanui Populations.
abstract: BACKGROUND
  Chile is one of the countries with the highest prevalence of cholelithiasis worldwide, considering the Mapuche ethnicity as a risk factor for developing this pathology. Moreover, cholelithiasis is the main risk factor for developing gallbladder cancer, being the fifth cause of cancer death in Chile. The purpose of this study was to compare the frequency of cholelithiasis and biliary pathology among the population belonging to Rapanui ethnicity and non-Rapanui population living on Easter Island.
  
  
  METHODS
  In this retrospective case-control study, a total of 609 abdominal ultrasonographs performed consecutively in Hanga Roa Hospital during the period August 2012 to January 2015 were analyzed. Multiple logistic regression was used to obtain odds ratio (OR) and 95% confidence intervals (95% CI) of cholelithiasis and biliary pathology, adjusting for age, gender and referral diagnostic hypothesis.
  
  
  RESULTS
  In the Rapanui population the frequency for cholelithiasis and biliary pathology was 6.4% and 13%, meanwhile for the non-Rapanui population it was 13% and 22% respectively. Compared to the non-Rapanui Chilean population, the Rapanui ethnicity presented an OR of 0.53 (95% CI: 0.29-0.95) for cholelithiasis and OR of 0.52 (95% CI: 0.33-0.82) for biliary pathology.
  
  
  CONCLUSIONS
  We found statistically significant ethnic differences in the frequency of cholelithiasis and biliary disease among the population of Rapanui and non-Rapanui ethnicity, so that this could be a protective factor for the development of biliary pathology, given the Chilean population context. Other studies including community population to determine the real prevalence of cholelithiasis and analyze the protective role of Rapanui ethnicity on this disease are necessary.
authors.affiliation: Department of Radiology, Hospital Clinico Universidad de Chile, Santiago, Chile E-mail : eduardo.bravo.rius@gmail.com.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Bravo
authors.forename: Jorge
authors.initials: J
authors.lastname: Contardo
authors.forename: Jerson
authors.initials: J
authors.lastname: Cea
mesh_terms: D000293:Adolescent; D000328:Adult; D001660:Biliary Tract Diseases / Q000175:diagnosis / Q000453:epidemiology*; D016022:Case-Control Studies; D002677:Chile / Q000453:epidemiology; D002769:Cholelithiasis / Q000175:diagnosis / Q000453:epidemiology*; D005006:Ethnicity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult