Gastrointestinal Endoscopy
Volume 66, Issue 3 , Pages 541-543, September 2007

Postoperative endoscopic surveillance in Crohn's disease: bottom up or top down?

Division of Gastroenterology, University Hospitals Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA

Article Outline

Abbreviation: CE, capsule endoscopy

 

No validated scoring system for postoperative evaluation with capsule endoscopy exists, and, most importantly, there is no clear clinical correlation between capsule endoscopic findings and clinical symptom recurrence in postoperative Crohn's disease.

Despite significant advances in our understanding and treatment of Crohn's disease, postoperative disease recurrence, typically on the proximal side of an anastomosis, remains a common and important problem. In population-based studies, over a half of all patients with Crohn's disease will require surgery within 10 years of diagnosis1, 2 and, of these, about 20% will need at least 1 additional operation in the ensuing decade.1 To limit the recurrence in Crohn's disease, postoperative maintenance medical therapy with 5-aminosalicylates3 or immunomodulators4, 5 is routinely recommended, though the potency of these therapies in preventing clinical relapse is at best marginal.

Clinical relapse, however, is preceded in most patients by endoscopic relapse,6 providing an enticing opportunity for intervention aimed at delaying and/or preventing future complications. Systematic endoscopic studies of the neoterminal ileum after surgical resection show evidence of recurrent Crohn's disease in nearly 75% of patients 1 year after surgery,6, 7 although clinical symptoms directly attributable to such lesions are present in only 20% of these patients. An endoscopic scoring system based on examination of the neoterminal ileum, the Rutgeerts score,6 is commonly used in clinical trials as a surrogate marker for risk of clinical relapse. Recurrent ileal lesions are scored as i,0 (no lesions), i,1 (<5 aphthous lesions), i,2 (>5 aphthous lesions with normal mucosa between the lesions, or skip areas of larger lesions or lesions confined to the ileocolonic anastomosis [<1 cm in length]), i,3 (diffuse aphthous ileitis with diffusely inflamed mucosa), and i,4 (diffuse inflammation with larger ulcers, nodules, and/or narrowing). The severity of endoscopic lesions in the first year after surgery is, to date, the best predictor of the postoperative course of Crohn's disease. About 80% of patients with an i,0 or an i,1 score are asymptomatic over 3 years, whereas less than 10% of patients with i,3 or i,4 scores remain well.6 Based on this information, it has been proposed that patients with Crohn's disease have endoscopic evaluation of the neoterminal ileum 6 to 12 months after ileocolonic anastomosis to guide therapeutic management.8

Though routinely used to evaluate Crohn's disease after surgery, ileocolonoscopy requires a bowel preparation, is invasive, can be uncomfortable, and carries small but real risks. Furthermore, thorough endoscopic examination of an ileocolic anastomosis can be technically difficult and may not always be successful. With the growing use of capsule endoscopy (CE) in patients with Crohn's disease,9 it is logical to consider CE as an attractive alternative to ileocolonoscopy in evaluating endoscopic recurrence after surgery.

In this issue of the Gastrointestinal Endoscopy, Pons et al10 evaluated the safety, accuracy, and therapeutic impact of CE compared with ileocolonoscopy in the postoperative evaluation of 24 patients with Crohn's disease. All study patients had undergone an ileocolonic resection with side-to-side anastomosis in the past 6 to 12 months. Patients were asymptomatic and not taking any postoperative maintenance therapy or nonsteroidal anti-inflammatory drugs. Within a 2-week period, a patency capsule examination to rule out any occult small-bowel stenosis, a CE, and an ileocolonoscopy were performed. All CE and ileocolonoscopy results were evaluated by a single experienced investigator, each of whom was blinded to the outcome of the other examination. The Rutgeerts score was used to grade both examinations, and recurrence was classified as a score of ≥i,2. The investigators also recorded lesions detected by CE in the proximal small bowel, patient preference for the 2 procedures, and changes in patient treatment after endoscopic evaluation.

Of 24 patients, 22 passed the patency capsule intact and had a CE. The CE examination was complete in 21 patients, and recurrent Crohn's disease was documented in the neoterminal ileum in 15 patients (62%). In addition, proximal small-bowel involvement was identified in 13 patients. Comparatively, ileocolonoscopy was successful in 21 of 24 patients, but neoterminal ileal recurrence was only detected in 6 patients (25%). CE detected disease recurrence in all patients who had positive findings on ileocolonoscopy (no false-negative CE examinations), but ileocolonoscopy did not detect recurrence in 8 patients who had neoterminal ileal lesions seen on CE. Based on information obtained exclusively on CE, therapeutic modification (azathioprine 2.5 mg/kg per day) was offered to and accepted by 7 of 10 patients. There were no complications with either procedure, but, not surprisingly, patients preferred CE to ileocolonoscopy.

The unexpected result in this study is not the lower number of endoscopic recurrence of Crohn's disease detected with ileocolonoscopy but rather the very high recurrence rate detected on CE. In the original paper detailing the Rutgeerts score, i,2 lesions at 1 year were only present in 17% of patients.6 Similarly, in another recently published paper, by Bourreille et al,11 that compared CE with ileocolonoscopy, i,2 lesions were seen in just 23% of CEs compared with 19% of ileocolonoscopies. The very high rate of ≥i,2 lesions on CE in the study of Pons et al10 suggests either an aggressive postoperative disease course in their study patients or a systematic overestimation of the Rutgeerts score by CE. Although multiple studies show an increased yield for CE compared with other modalities in detecting small-bowel Crohn's disease,12 it is also clear that CE can detect mucosal lesions, which are not clinically meaningful and may not even be caused by Crohn's disease.13 It is, after all, a purely visual technology, with no means of histologic confirmation of Crohn's disease. Also, significant interobserver variability can be present in CE interpretation,14 in particular, when assessing ileal ulceration.11

It is important to remember that the Rutgeerts score was specifically developed, rigorously studied, and validated in the endoscopic assessment of postoperative recurrence in Crohn's disease and was correlated with clinical disease activity and pathologic assessment.6, 7 The limited follow-up after the CE examination in this study does not allow for any meaningful clinical correlation. Applying the Rutgeerts score to CE may be reasonable, but, to be clinically useful, this approach needs to be validated and directly related to the clinical disease behavior. By using ileocolonoscopy as the criterion standard, other investigators estimated the sensitivity of CE to detect i,1 endoscopic ileal Crohn's disease recurrence at only 62% to 76%, compared with 90% for ileocolonoscopy; specificity ranged from 91% to 100% for CE.11 Sensitivity and specificity were slightly less for i,2 lesions. Given the inability to control the capsule during the endoscopic examination, one wonders how accurate the Rutgeerts score can really be in this role, because it requires careful tabulation of the number, size, and extent of ileal lesions. Indeed, some investigators have begun to develop and test a specific scoring index for CE in Crohn's disease.15

CE did detect proximal small-bowel lesions in 54% of patients, findings not found on ileocolonoscopy. Similar results have been reported by other investigators.11 The clinical significance of these findings is uncertain but likely is minor. Because CE was not done before surgery in this trial, it is impossible to know whether the CE findings represent postoperative recurrence of disease or simply disease that was present before surgery. Previous studies that used perioperative small-bowel endoscopy reported scattered proximal small-bowel lesions in 65% of patients,16 but, these findings had no effect on early anastomotic recurrence.17 Thus, although CE will find proximal small-bowel mucosal abnormalities in patients with Crohn's disease, past studies suggest that these findings are clinically unimportant.

Patients clearly prefer CE to ileocolonoscopy, and it is undoubtedly a safer examination. However, the risk of capsule retention is real and has been reported to be as high as 13% in patients with known Crohn's disease.18 Even among the study patients of Pons et al,10 who were just 6 to 12 months after surgery, the patency capsule did not pass in 2 patients (8%).10 Based on this experience, if CE were to routinely replace ileocolonoscopy in the postoperative endoscopic evaluation of Crohn's disease, either all patients would need a patency capsule examination before a CE or up to 10% of patients would be at risk for capsule retention. Although capsule retention may not necessarily require surgical intervention, it remains to be seen whether this risk is acceptable to these typically asymptomatic patients who were recently operated on for their Crohn's disease.

At this time, CE cannot be recommended as a replacement for ileocolonoscopy in the routine postoperative assessment of endoscopic recurrence in Crohn's disease. Despite its comfort and ease for the patient, the sensitivity and the specificity of the examination are, as yet, not as good as standard endoscopic evaluation. Furthermore, no validated scoring system for postoperative evaluation with CE exists, and, most importantly, there is no clear clinical correlation between CE findings and clinical symptom recurrence in postoperative Crohn's disease. However, the current shortcomings in the experimental data for CE are not insurmountable and Pons et al,10 along with other investigators,11 have begun to lay the foundations for additional studies in this area. These studies should include preoperative or very early postoperative CE, rigorous study design to minimize variability in interpretation, development of a validated study index, and longer-term follow-up and clinical correlation. As these data roll in, I would not be surprised if, in the future, postoperative endoscopic surveillance involves a “top down” approach by using CE.

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Disclosure 

The author has no real or potential conflict of interest with regard to this article.

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References 

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PII: S0016-5107(07)00401-4

doi:10.1016/j.gie.2007.02.060

Gastrointestinal Endoscopy
Volume 66, Issue 3 , Pages 541-543, September 2007

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