Colon cancer after a negative colonoscopy

http://www.ncbi.nlm.nih.gov/pubmed/21681506

Dig Dis Sci. 2011 Jun 17. [Epub ahead of print]
Predictors of Colorectal Cancer Following a Negative Colonoscopy in the Medicare Population.
Singh A, Kuo YF, Riall TS, Raju GS, Goodwin JS.

Source
Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch (UTMB), 301 University Blvd., Galveston, TX, 77555-0764, USA, amasingh@utmb.edu.

Abstract
BACKGROUND:
The incidence of colorectal cancer following a normal colonoscopy in the Medicare population is not known.

METHODS:
A 5% national sample of Medicare enrollees from 1996 to 2005 was used to identify patients undergoing complete colonoscopy. A colonoscopy not associated with any procedure (e.g., biopsy, polypectomy or fulguration) was defined as a negative colonoscopy. Patients with history of inflammatory bowel disease, colorectal cancer or death within 12 months of colonoscopy were excluded. A multivariable model was constructed to evaluate the factors associated with a new diagnosis of colorectal cancer in the period from 12 to 120 months following the negative colonoscopy.

RESULTS:
Among 200,857 patients (mean age 74 years, 61% female, 92% White) with a negative colonoscopy, the incidence of colorectal cancer was 1.8 per 1,000 person-years. The incidence rate for matched follow-up periods decreased from 2.0/1,000 person-years for patients undergoing colonoscopy during 1996-2000 to 1.2/1,000 person years during 2001-2005. Multivariate analysis revealed a significant regional variation in the incidence of colorectal cancer following a negative colonoscopy. The incidence was higher in patients >85 years, males and patients who underwent a negative colonoscopy by a non-gastroenterologist or endoscopist in the lowest volume quartile. On stratified analyses, endoscopist volume was a significant predictor for non-gastroenterologists only.

CONCLUSIONS:
The specialty and experience of the endoscopist are significant predictors of the incidence rate of colorectal cancer in Medicare patients with a negative colonoscopy.