title: Evaluating risk: a primer for gastroenterologists.
abstract: OBJECTIVE
  To review the various types of risk measures and to illustrate how interpretations may vary depending on how risk is presented.
  
  
  METHODS
  We define different types of risk estimates and provide examples of their use from the recent gastroenterological literature.
  
  
  RESULTS
  Calculations of absolute risk and the number of patients who must receive treatment to prevent one patient from experiencing a disease state (number needed to treat) provide useful information in assessing the utility of fecal occult blood testing for prevention of colorectal cancer and in estimating small bowel cancer rates for individuals with familial adenomatous polyposis.
  
  
  CONCLUSIONS
  Measures such as relative risk and the odds ratio are best used in analyzing causality but may not be helpful in guiding clinical decisions. Absolute risk and attributable risk reveal the actual number of cases that can be explained by a given exposure and can thereby measure the impact of a clinical intervention for both the population and the patient. These measures should be the criteria for decision-making.
authors.affiliation: Division of Digestive Diseases and Nutrition, University of North Carolina at Chapel Hill, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Eisen
authors.forename: R S
authors.initials: RS
authors.lastname: Sandler
authors.forename: J I
authors.initials: JI
authors.lastname: Wurzelmann
authors.forename: D F
authors.initials: DF
authors.lastname: Ransohoff
authors.forename: A
authors.initials: A
authors.lastname: Talal
mesh_terms: D011125:Adenomatous Polyposis Coli / Q000473:pathology; D001241:Aspirin / Q000008:administration & dosage; D015179:Colorectal Neoplasms / Q000401:mortality / Q000517:prevention & control; D004379:Duodenal Neoplasms / Q000473:pathology; D006801:Humans; D007414:Intestinal Neoplasms / Q000209:etiology; D009780:Occult Blood; D012306:Risk; D012307:Risk Factors
chemical_list: D001241:Aspirin