Quality Assurance for Screening Colonoscopies

Introduction

Three methods of preventing colorectal cancer are widely accepted: the fecal occult blood test (FOBT), the flexible sigmoidoscopy and the screening colonoscopy. Three large randomized trials with an annual application of the FOBT have revealed a significant decrease of colorectal cancer mortality and incidence in the screened population. Good evidence indicates that flexible sigmoidoscopy is an effective screening method, too. As far as the effectiveness of colonoscopy as a screening tool is concerned, however, only indirect evidence has so far been derived from the US national polyp study [1].

Nevertheless, the screening colonoscopy is recommended as the gold standard for colorectal cancer prevention. Its effectiveness, however, has been disputed since an article by Robert Barclay and colleagues in the New England Journal of Medicine in December 2006 found a great variation in the detection rate of adenomas which correlates with the withdrawal time of the colonoscope [2]. This questions the effectiveness of the screening colonoscopy for colorectal cancer prevention in general. Another study on missed carcinomas recently published in Gastroenterology showed a 2 - 6 % miss rate after colonoscopy in usual practice [3].

References

• 1 Winawer S J, Zauber A G, Ho M N. et al . Prevention of Colorectal Cancer by colonoscopic polypectomy.  N Engl J Med. 1993;  329 1977-1981
• 2 Barclay R L, Vicari J J, Doughty A S. et al . Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.  N Engl J Med. 2006;  355 2533-2541
• 3 Bressler B, Paszat L F, Chen Z. et al . Rates of new or missed colorectal cancers after colonoscopy and their risk factors: A population-based Analysis.  Gastroenterology. 2007;  132 96-102
• 4 The New York Times .Study questions colonoscopy effectiveness. Dec 14, 2006
• 5 Rex D, Petrini J M, Baron T H. et al . Quality indicators for colonoscopy.  Gastrointest Endosc. 2006;  63 S 16
• 6 Augustin V, Ferrari U, Birkner B. et al . Web based documentation portal for outpatient colonoscopies in Bavaria (Germany): A tool for quality assurance and health care services research.  Gastrointest Endosc. 2007;  65 AB 367
• 7 New York City Department of Health and Mental Hygiene .A practical guide to increasing screening colonoscopy. http://www.nyc.gov/html/doh/downloads/pdf/cancer/cancer-colonoscopy-guide.pdf