title: Predictive value of a positive fecal occult blood test increases as the severity of CKD worsens.
abstract: BACKGROUND
  Because chronic kidney disease (CKD) may be associated with gastrointestinal bleeding from trivial mucosal lesions, we hypothesized that the predictive value of a positive fecal occult blood test (FOBT) result for clinically important colonic lesions would decrease as the stage of CKD worsened.
  
  
  METHODS
  We prospectively identified 1,225 consecutive asymptomatic average-risk patients who were referred for colonoscopy to evaluate a positive FOBT result. Using the Modification of Diet in Renal Disease equation, we estimated glomerular filtration rate (GFR) and staged the severity of CKD by using standard criteria as follows: normal/stage 1 (GFR > or = 90 mL/min/1.73 m2 [> or = 1.50 mL/s]), stage 2/3 (GFR 30 to 89 mL/min/1.73 m2 [0.50 to 1.48 mL/s]), and stage 4/5 (GFR < 30 mL/min/1.73 m2 [< 0.50 mL/s] or dialysis).
  
  
  RESULTS
  Clinically important lesions were identified in 23.9% of 531 individuals with none/stage 1 CKD, 32.8% of 497 subjects with stage 2/3 CKD, and 42.6% of 197 patients with stage 4/5 CKD (P < 0.001). Compared with patients with none/stage 1 CKD, adjusted odds of identifying a clinically important lesion were 1.61 (95% confidence interval, 1.21 to 2.15) in subjects with stage 2/3 CKD and 2.33 (95% confidence interval, 1.62 to 3.36) in patients with stage 4/5 CKD. Prevalences of adenomas of 1 cm or greater (15.1% versus 20.1% versus 22.8%; P = 0.007), carcinomas (5.1% versus 10.1% versus 13.2%; P < 0.001), and vascular ectasias (1.7% versus 2.4% versus 6.1%; P = 0.003) increased with the severity of CKD.
  
  
  CONCLUSIONS
  Contrary to our initial hypothesis, we found that the predictive value of a positive FOBT result for clinically important colonic lesions increased as the severity of CKD worsened.
authors.affiliation: Division of Gastroenterology, Veterans Affairs New York Harbor Healthcare System, New York, NY 10010, USA. edmund.bini@med.va.gov
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Bini
authors.forename: Aditi
authors.initials: A
authors.lastname: Kinkhabwala
authors.forename: David S
authors.initials: DS
authors.lastname: Goldfarb
mesh_terms: D000368:Aged; D002908:Chronic Disease; D015179:Colorectal Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D018450:Disease Progression; D005189:False Positive Reactions; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007674:Kidney Diseases / Q000150:complications* / Q000473:pathology*; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012720:Severity of Illness Index