title: Sex differences in performance of fecal occult blood testing.
abstract: OBJECTIVE
  Immunological and guaiac-based fecal occult blood tests (iFOBTs and gFOBTs) are widely used for early detection of colorectal cancer (CRC). We aimed to assess potential sex differences in performance of iFOBTs and gFOBT in the screening setting.
  
  
  METHODS
  The sensitivity, specificity, and positive and negative predictive values for detection of advanced colorectal neoplasms (CRC or advanced adenoma) were assessed by sex for a range of cutpoints of a quantitative iFOBT (RIDASCREEN Hemoglobin), six qualitative iFOBTs, and a gFOBT (HemOccult) among 1,157 male and 1,167 female participants of the German screening colonoscopy program (mean age: 63.0 and 62.0 years, respectively).
  
  
  RESULTS
  The prevalence of advanced colorectal neoplasms was much higher among men (13.5%) than among women (7.5%). At any cutpoint of the quantitative iFOBT, and for all qualitative iFOBTs and the gFOBT, the sensitivity and positive predictive value were substantially higher, and specificity and negative predictive value were substantially lower among men than among women. At the cutpoint of 2 μg/g stool given by the manufacturer of the quantitative iFOBT, sensitivity, specificity, and the positive and negative predictive values were 47.6, 85.0, 33.0, and 91.3% among men, and 30.7, 89.5, 19.3, and 94.1% among women (P value for sex differences 0.001, 0.002, 0.004, and 0.019, respectively). Sex differences in predictive values were mostly explained by sex differences in the prevalence of advanced colorectal neoplasms.
  
  
  CONCLUSIONS
  There are major sex differences in the performance of fecal occult blood testing, which might require careful attention in the interpretation of test results, and in the design, modeling, and evaluation of CRC screening strategies.
authors.affiliation: Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Heidelberg, Germany. h.brenner@dkfz.de
authors.forename: Hermann
authors.initials: H
authors.lastname: Brenner
authors.forename: Ulrike
authors.initials: U
authors.lastname: Haug
authors.forename: Sabrina
authors.initials: S
authors.lastname: Hundt
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D055088:Early Detection of Cancer / Q000379:methods*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006138:Guaiac; D006801:Humans; D008297:Male; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012727:Sex Characteristics
chemical_list: D006138:Guaiac