Rutgeerts Score Interpreter for Postoperative Crohn’s Disease
Rutgeerts Score Interpreter for Postoperative Crohn's Disease
Five endoscopic grades at the neoterminal ileum after an ileocolonic resection. In a 365-patient cohort, cumulative clinical recurrence ran 28%, 35%, 49%, 64% and 84% from i0 to i4.
Rutgeerts score
Endoscopic grade → i0–i4More than five aphthous lesions in the neoterminal ileum with normal mucosa between them, at ileocolonoscopy eight months after an ileocolonic resection
The five grades, and the modified split
Modified score splits i2 only: i2a confined to the anastomosis · i2b more than five lesions in the neoterminal ileum. i0, i1, i3 and i4 are unchanged.
- i2 is the recurrence threshold
- endoscopic recurrence is conventionally i2 or above; the PREVENT trial defined it that way and contemporary trials use a modified score of i2a or above. ECCO-ESGAR separately names i3 and i4 as the validated cut-offs for predicting clinical relapse, which is a stricter line than i2
- exactly five lesions is disputed
- Hanzel’s reproduction gives i1 as five or fewer and i2 as more than five; the Leuven supplementary table gives i1 as fewer than five and i2 as five or more. An ileum with exactly five aphthous lesions is i1 under one and i2 under the other — a one-grade disagreement straddling the recurrence threshold. Record the lesion count, not only the grade
- i2a and i2b are not the same prognosis
- in a French cohort of 225, i2b had significantly shorter recurrence-free survival than i0 and i2a did not differ from i0. A retrospective cohort of 365 found no difference between i2a and i2b. For progression to i3 or i4, i2a’s risk versus i0/i1 was a hazard ratio of 2.30 (95% CI 0.80 to 6.66) in one study and an adjusted odds ratio of 2.11 (95% CI 0.89 to 4.97) in another — both underpowered, both intervals crossing 1
- the 1990 cohort size is not quoted here
- no source read gave the number of patients or the follow-up of Rutgeerts’s own 1990 derivation study, which is paywalled. The percentages on this page are therefore the Leuven cohort’s — 365 patients, median 88 months — and are labelled as such rather than attributed to the original paper
- an endoscopic grade is not a symptom
- the grade describes the mucosa at one endoscopy. Clinical recurrence is a different event with a different timescale, and the gap between them runs both ways — 28% of patients with a normal endoscopy in the Leuven cohort still recurred clinically, and 16% of those at i4 did not
Worked example
More than five aphthous lesions in the neoterminal ileum with normal mucosa between them, at ileocolonoscopy eight months after an ileocolonic resection
More than five aphthous lesions with normal intervening mucosa is i2 on the original score
The lesions are in the neoterminal ileum rather than confined to the anastomosis, which makes it i2b on the modified score
i2 is the conventional threshold for endoscopic recurrence. In the Leuven cohort of 365 patients, 88 of the 180 at i2 (49%) had clinical recurrence over a median 88 months
The split matters: had these lesions been confined to the anastomosis (i2a), the French cohort of 225 found no difference in recurrence-free survival from i0 — while i2b was significantly worse
And the count matters. With exactly five lesions instead of more than five, this would be i1 under one published wording and i2 under another, which is why the lesion count belongs in the report alongside the grade
Clinical recurrence by grade
| Grade | Patients at that grade | Cumulative clinical recurrence |
|---|---|---|
| i0 | 74 of 365 (20%) | 21 of 74 — 28% |
| i1 | 37 of 365 (10%) | 13 of 37 — 35% |
| i2 | 180 of 365 (49%) | 88 of 180 — 49% |
| i3 | 42 of 365 (12%) | 27 of 42 — 64% |
| i4 | 32 of 365 (9%) | 27 of 32 — 84% |
Where the published wordings disagree
| Grade | Hanzel 2022 (original and modified) | Leuven supplementary table | The finding it moves |
|---|---|---|---|
| i1 | Five or fewer aphthous lesions | Less than five aphthous lesions | Exactly five lesions: i1 on the left, i2 on the right. |
| i2 | More than five aphthous lesions with normal intervening mucosa, or lesions confined to the anastomosis | Five or more aphthous lesions with normal mucosa in between | The same boundary, from the other side. |
| i3 | Diffuse aphthous ileitis with diffusely inflamed mucosa | More than five aphthous lesions with diffusely inflamed mucosa in between | None in practice — both turn on the intervening mucosa being inflamed. |
| i4 | Large ulcers with diffuse mucosal inflammation, or nodules, or stenosis in the neoterminal ileum | Large ulcers with diffuse mucosal inflammation in between, or nodules, or stenosis in the distal ileum | None. |
Endoscopy at six to twelve months, because symptoms come later
After an ileocolonic resection for Crohn’s disease, lesions reappear at the neoterminal ileum long before the patient notices anything. Placebo arms of postoperative trials report endoscopic recurrence in 50 to 58% of patients within 52 weeks, and in the Leuven postoperative cohort only 20% of 365 patients had a completely normal ileum when they were scoped. The Rutgeerts score, published in 1990, grades what the endoscope sees so that the reappearance can be acted on before it becomes symptomatic. That is the entire rationale for scoping an asymptomatic patient at six to twelve months after surgery.
Five grades, i0 to i4, turning on how many aphthous lesions there are, whether the mucosa between them is normal or inflamed, and whether there are large ulcers, nodules or a stenosis. In the Leuven cohort the gradient is monotonic and steep: cumulative clinical recurrence over a median 88 months was 28% at i0, 35% at i1, 49% at i2, 64% at i3 and 84% at i4. Those are the figures this page quotes, because no source available here reported the cohort size or follow-up of Rutgeerts’s own 1990 study. Note what the extremes say: 28% of patients with a normal ileum recurred anyway, and 16% of those with large ulcers did not. The score stratifies well and determines nothing.
Half the cohort sat at i2, which is both the conventional threshold for endoscopic recurrence and a grade that lumps two different findings together — more than five lesions in the ileum, and lesions confined to the anastomosis. The modified score separates them as i2b and i2a, and that is the only change it makes; i0, i1, i3 and i4 are identical. The evidence for the split is real but thin. In a French cohort of 225 patients, i2b had significantly shorter recurrence-free survival than i0 while i2a did not differ from i0 at all; a retrospective cohort of 365 found no difference between the two. For progression to i3 or i4, i2a’s risk against i0 or i1 was a hazard ratio of 2.30 with a 95% confidence interval of 0.80 to 6.66 in one study and an adjusted odds ratio of 2.11 with an interval of 0.89 to 4.97 in another — both underpowered, both intervals crossing 1. So the grade with the weakest evidence is the one that most often crosses a management threshold.
Two cautions. First, the published wordings disagree at exactly five lesions: one reproduction puts five or fewer at i1 and more than five at i2, another puts fewer than five at i1 and five or more at i2. An ileum with exactly five aphthous lesions is i1 under one and i2 under the other, straddling the recurrence threshold, and the 1990 paper is paywalled so neither can be checked against the original. Record the lesion count as well as the grade. Second, this is an endoscopic grade and not a measure of how the patient feels: a CDAI or an Harvey–Bradshaw index can be high at i0 because of bile-acid diarrhoea after resection or a mechanical stenosis, and low at i4. The faecal calprotectin interpreter and the CRP unit converter are what sit between endoscopies. A score is not a diagnosis and a figure from a cohort is not a probability for one patient. This states what the number meant in a named study; the clinician in front of the patient decides what follows. Thresholds here are the published ones; reference intervals and assay units are method- and laboratory-dependent and your own laboratory’s interval takes precedence.
Frequently asked questions
What Rutgeerts grade counts as endoscopic recurrence?
i2 or above on the original score, and i2a or above on the modified score in contemporary trials; the PREVENT trial used i2 or above. ECCO-ESGAR separately names i3 and i4 as the validated cut-offs for predicting clinical relapse, which is a stricter line — so two defensible thresholds are in use and they are not the same.
What is the difference between i2a and i2b?
The modified score splits the original i2. i2a is lesions confined to the ileocolonic anastomosis, including anastomotic stenosis. i2b is more than five aphthous lesions in the neoterminal ileum, with or without anastomotic lesions. In a French cohort of 225, i2b had shorter recurrence-free survival than i0 while i2a did not differ from i0; another cohort of 365 found no difference between the two. i0, i1, i3 and i4 are the same in both versions.
Is a grade of i1 reassuring?
Partly. In the Leuven cohort 13 of the 37 patients at i1 (35%) had clinical recurrence over a median 88 months, against 28% at i0 and 49% at i2 — so i1 sits closer to normal than to recurrence but is not a normal result. And if the ileum had exactly five lesions, whether it is i1 at all depends on which published wording the report followed.
When should the endoscopy be done?
Conventionally six to twelve months after an ileocolonic resection, because endoscopic lesions reappear well before symptoms — placebo arms of postoperative trials report endoscopic recurrence in 50 to 58% of patients within 52 weeks. The timing is a guideline question rather than part of the score, and the score itself says nothing about when to look.
Does the Rutgeerts score apply to Crohn’s disease that has not been operated on?
No. Every grade refers to the neoterminal ileum and the ileocolonic anastomosis after a resection, and the score was derived to predict the postoperative course. Endoscopic activity in unoperated Crohn’s disease is graded with a different instrument, and using Rutgeerts grades for it reports a number that has never been validated in that population.
Related calculators
References
- Hanzel J, Ma C, Jairath V. Endoscopic assessment of postoperative Crohn’s disease: the Rutgeerts score and its modification. Gastroenterol Hepatol (N Y). 2022;18(10).
- Rates of postoperative recurrence of Crohn’s disease and effects of immunosuppressive and biologic therapies — Leuven postoperative cohort, Supplementary Table 1. lirias.kuleuven.be.
- Sturm A, Maaser C, Calabrese E, et al. ECCO-ESGAR guideline for diagnostic assessment in IBD part 2: IBD scores and general principles and technical aspects. J Crohns Colitis. 2019;13(3):273–84. doi:10.1093/ecco-jcc/jjy114
- Janssen. Protocol CNTO1959CRD3006 — modified Rutgeerts score as the endoscopic recurrence endpoint. NCT05784129, clinicaltrials.gov.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/