Letter: The Simple Endoscopic Score for Predicting Crohn's Disease Progression—Not as Simple as It Sounds

We read with interest the study by Peraza and colleagues examining the role of the Simple Endoscopic Score for Crohn's Disease (SES-CD) in defining mild Crohn's disease (CD) and predicting the risk of disease progression [1].

SES-CD is a well-established endoscopic scoring system used to assess CD severity based on ulcer size, ulcerated surface, affected surface without ulceration and stenosis [2]. SES-CD correlates with the more extensive Crohn's Disease Endoscopic Index of Severity and faecal calprotectin [3, 4].

Peraza et al. performed a retrospective analysis of 177 patients with CD from three major referral centres. They concluded that SES-CD ≥ 7 is an independent predictor of disease progression [1]. However, several limitations require further consideration.

The median disease duration at the time of endoscopy was 17 years, meaning that many patients had already declared their risk of progression or non-progression. In a population-based study, the cumulative risk of developing stricturing and/or penetrating complications was approximately 50% at 20 years post-diagnosis [5]. Despite this extended disease duration in this study, one-third of patients had an SES-CD score of 0 in the absence of current immunomodulator or biologic therapy, bringing the diagnosis of CD into question. How many of these patients had previously been treated with medical therapy for CD? What proportion simply reflects patients with previous isolated terminal ileal aphthous ulcers or ileitis without other evidence for CD, as is commonly encountered in clinical settings? [6] Hence, the study population may represent a less complex cohort, contrary to the authors' claim of including a more complex patient population.

Among this cohort, 14% had stricturing and 4% had fistulising disease at baseline. These complications would already classify such patients as moderate-to-severe, having had progression of their disease, and eligible for medical therapy to prevent further complications [7]. Therefore, inclusion of these patients does little to guide management decisions, particularly given the potential discrepancy between endoscopic and transmural findings in some patients [8].

The authors highlighted the advantage of SES-CD in assessing ileal and colonic disease activity separately, noting that an SES-CD ≥ 7 was more predictive of disease progression in ileal and ileocolonic disease than in isolated colonic disease. However, the study did not differentiate patients with small bowel CD or assess the predictive utility of SES-CD in this subgroup. An SES-CD of 4–6 in a patient with isolated ileal CD requires at least one or more of large ulcers (> 5 mm), ulcerated surface > 10%, affected surface > 50%, or narrowing. Hence, these patients would no longer be regarded as having mild disease, as recognised by inclusion criteria for most clinical trials in CD.

In conclusion, while SES-CD is a simple and reproducible endoscopic scoring system for assessing CD activity and has intuitive attractiveness for use in predicting disease progression, the study by Peraza and colleagues may not have been sufficiently robust to draw such conclusions or guide management decisions in patients with differing durations or distributions of CD.