Complications of Colonoscopy in an Integrated Health Care Delivery System

Levin et al, report a major complication in about one in 200 colonoscopies and a perforation rate approaching one in a thousand (1). They point out that their results are consistent with other reports on complications (Table 1). However, if we (or any large private practice gastroenterology group) had such a complication rate it would be cause for concern and in need of review.

The authors and editors state that a limitation of this study is that less than one percent were screening colonoscopies and thus the complication rate may be higher than a screening group. In fact their study specifically excluded all diagnostic colonoscopy and only looked at what we would consider screening or surveillance colonoscopy. These are low risk cases.

We suspect that the issue here is experience. We believe a teaching institution where most of the procedures are done by residents and fellows would have the highest complication rates and high volume private practice ambulatory centers would have the lowest. In the past six years we have had three perforations in 25,254 cases; a perforation rate 7.5 times less then the Kaiser group. (If we did not include our 2006 data our perforation rate would be one tenth of the Kaiser group). As seen in Table 1 most data on perforation come from teaching centers. There are two large studies from high volume private practice groups. The rate of perforation in these studies is less than a third of most of the other studies which had 10,000 procedures or more. (Studies with low a number of procedures are unreliable in determining the rate of an event which is uncommon).

Assuming Kaiser did not have residents or fellows doing procedures (there is no mention of this in their study), then one needs to ask why they should have such a high rate of perforation? In a study of 16,000 colonoscopies we know that 39 doctors did an average of 79 cases; but we do not know how many endoscopists were involved in the study. One endoscopist with 6 complications did 808 cases (the study is over 8 years so that may be only 100 cases per year). We do not know if there are other endoscopists who have a high rate of major complications. We do know that 20% of endoscopists do less then 150 procedures a year. What percent do only 200 per year? How many years experience do they have? Is one major complication in every 150 cases acceptable? This retrospective chart review raises important questions.

W. Michael McDonnell, M.D., F.A.C.P. Fritz Loura, M.D. Western Washington Medical Group Everett, WA 98203

1. Levin TR, Zhao W, Conell C, Seeff LC et al. Ann Intern Med. 2006: 145:880-886

Table 1 (Please allow us to submit a table formated with MS Word)

Author Journal Year Colons Perfs Percent Setting

Waye JD J Clin Gastroenterol. 15:347-51 1992 2097 2 0.095 Office/ private

Lo AY Am Coll Surg. 179:333-7 1994 26,708 12 0.045 University/ teaching

Farley DR Mayo Clin Proc. 72:729-33 1997 57,028 43 0.075 Mayo/ teaching

Zubarik RG Gastrointest Endosc. 50:322-8 2000 1196 0 0 University/ teaching

Anderson ML Am J Gastroenterol. 95:3418-22 2000 10,486 20 0.19 Mayo/teaching

Imperiale TF N Engl J Med. 343:169-74 2000 1994 1 0.5 University/ teaching

Araghizadeh FY Dis Colon Rectum. 44:713-6 2001 34,620 31 0.09 University/teaching

Nelson DB Gastrointest Endosc. 55:307-14 2002 3196 0 0 VA/teaching

Misra T Can J Gastroenterol. 18:221-6 2004 7,425 10 0.13 University/teaching

Korman LY Gastrointest Endosc. 58:554-7 2004 116,000 37 0.03 ASC/ private

Cobb WS Am Surg. 70:750-7 2004 43,609 14 0.032 teaching

Iqbal CW J Gastrointest Surg. 9:1229-35 2005 78,702 66 0.084 Mayo/ teaching

Rathgarber SW Gastrointest Endosc.64:556-6 2006 12,407 2 0.016 Private

Levin TR Ann Intern Med 145:880-886 2006 16,318 15 0.09 Kaiser

McDonnell WM unpublished 2006 25,254 3 0.012 ASC/private

Conflict of Interest:

None declared

I thank Drs. McDonnell and Loura for their interest in our paper. Their comments reflect what may be a misunderstanding about how our study was conducted, which procedures and patients were included and the status and training of the endoscopists in our study.

First, all the endoscopists included in our study were staff physicians, and no trainees were involved. Second, over half of the identified colonoscopies in the various databases used to build the study data set were not included in the analysis. Of the 35,945 identified, only 16,318 were eventually included in the study dataset. For the period 1994- 96, the Colon Cancer Prevention (CoCaP) Program database only included colonoscopies done within 6 months of a flexible sigmoidoscopy. Therefore the numbers of colonoscopies described per endoscopist represent only a fraction of the endoscopic activity of these endoscopists. Each endoscopist performed more procedures than were included in the eventual study dataset.

We had a significantly higher rate of polyp detection and removal in our sample than one would have expected in a purely screening or surveillance population, primarily because most of our patients had a prior positive test, such as a flexible sigmoidoscopy, a barium enema, a fecal blood test, or a positive family history. Our perforation rate was clearly related to the removal tissue at colonoscopy, primarily through the use of snare resection with electrocautery. When no tissue was removed, we had only 3 perforations in 5235 procedures, 2 of which occurred in patients with abnormal colons, either due to unsuspected colitis, or a tortuous, narrowed sigmoid colon.

Our study had systematic follow-up for all hospitalizations using automated, electronic data to track hospitalizations. While not specified, I would presume the University of Washington experience reported by Drs. McDonnell and Loura relied on self reported or opportunistic follow-up of post-colonoscopy complications. I would question whether they have complete information on delayed perforations that may have occurred in patients who were not hospitalized at their medical center. As described by Zubarik, et al (Gastrointest Endosc. 1999 Sep;50(3):322-8.), physician self-report of complications tends to miss complications that occurr when systematic follow-up is employed.

The one physician reported to have 6 complications over 808 cases, did many more colonoscopies than were reported in this study. He tended to be referred the more difficult polyp removal cases and therefore had a higher rate of complications than some of his colleagues.

Conflict of Interest:

None declared