Mayo Score Calculator for Ulcerative Colitis
Mayo Score Calculator for Ulcerative Colitis
The full four-item Mayo score, endoscopy included, 0 to 12. It is not interchangeable with the partial score, and the trial definition of remission is a total of 2 or less WITH no individual subscore above 1.
Mayo score
4 subscores → 0–123 to 4 stools more than normal (2), streaks of blood less than half the time (1), moderate disease on endoscopy (2), moderate global assessment (2)
Scoring
Remission: total 2 or less AND no subscore above 1 · trial entry 6–12 with endoscopic subscore 2 or more · response: fall of 3 or more points and 30% or more
- three Mayos, three maxima
- the FULL score is all four items, 0–12. The PARTIAL score drops endoscopy, 0–9. The MODIFIED score drops the global assessment instead, also 0–9. Two different 9-point scores are in circulation and a figure quoted as “Mayo 6 out of 9” is ambiguous without saying which
- remission is a conjunction
- a total of 2 or less AND no individual subscore above 1. Reporting only the total admits a patient with an endoscopic subscore of 2 and three zeros, who is not in remission by any definition
- stool frequency is relative
- scored against the patient’s own normal daily number, not against an absolute count. It is the item most often scored absolutely by mistake, and doing so misclassifies anyone whose baseline was not one or two stools a day
- the global assessment has no definition
- normal, mild, moderate, severe, and nothing more. It is a quarter of the score and it is an opinion, which is the main argument for the modified score that drops it
- it was never validated as an index
- the four subscores come from the outcome assessment of one 87-patient six-week trial of coated 5-ASA (Schroeder, Tremaine and Ilstrup, 1987), whose abstract does not name a disease activity index at all. It became the standard by use, not by validation
Worked example
3 to 4 stools more than normal (2), streaks of blood less than half the time (1), moderate disease on endoscopy (2), moderate global assessment (2)
2 + 1 + 2 + 2 = 7 points
7 is inside the 6–12 window every trial read uses for moderately-to-severely active disease, and the endoscopic subscore of 2 meets the additional entry requirement
The partial Mayo for the same patient is 2 + 1 + 2 = 5 — the same patient, a different number, and the two are not interchangeable
The modified Mayo, which drops the global assessment instead, is also 5 here — but only because the two dropped items happen to score the same
Response in a trial would need a fall of at least 3 points and at least 30% from this patient's own baseline, so 7 on its own says nothing about whether treatment is working
The four subscores
| Subscore | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| Stool frequency | Normal number for this patient | 1–2 more than normal | 3–4 more than normal | 5 or more than normal |
| Rectal bleeding | No blood seen | Streaks of blood less than half the time | Obvious blood most of the time | Blood alone passes |
| Findings on endoscopy | Normal or inactive disease | Mild: erythema, decreased vascular pattern | Moderate: marked erythema, lack of vascular pattern, any friability, erosions | Severe: spontaneous bleeding, ulceration |
| Physician’s global assessment | Normal | Mild disease | Moderate disease | Severe disease |
Which Mayo is which
| Score | Items | Range | Where it is used |
|---|---|---|---|
| Full Mayo | All four | 0–12 | Trial entry (6–12 with endoscopic subscore 2 or more) and the remission definition. |
| Partial Mayo | Drops endoscopy | 0–9 | Visits where endoscopy is not done. Remission is quoted as 2 or less, as 1 or less, and as under 1, depending on the source. |
| Modified Mayo | Drops the global assessment | 0–9 | Newer trials, including LUCENT 1, which uses a modified score of 4 to 9 for entry. |
| Endoscopic subscore alone | One item | 0–3 | Mucosal healing endpoints. Defined as 0 or 1 in most trials and as 0 alone by a meta-analysis of 15 studies. |
Four items, three versions of the name, and one subscore that carries the endpoint
The Mayo score was not designed as a disease activity index. It was the outcome assessment of a single trial — Schroeder, Tremaine and Ilstrup’s 1987 study of coated 5-aminosalicylic acid in 87 patients over six weeks — whose abstract does not name an index at all. It became the standard ulcerative colitis endpoint by use rather than validation, and one comparative study says the same of its endoscopic subscore: never formally validated, adopted through routine clinical use.
Four items, each 0 to 3: stool frequency against the patient’s own normal, rectal bleeding, the endoscopic appearance, and a physician’s global assessment. The first two are patient-reported and in trials are three-day averages; the fourth has no definition beyond its four adjectives. The third is the one that matters, and the Mayo endoscopic subscore interpreter exists because of it.
Two things are routinely got wrong. First, remission is a CONJUNCTION: a total of 2 or less AND no individual subscore above 1. Both the VARSITY protocol and ECCO-ESGAR state the pair together, and a patient with an endoscopic subscore of 2 and three zeros has a total of 2 and is not in remission. Second, “Mayo” names four instruments: the full score (0 to 12), the partial Mayo score (0 to 9, no endoscopy), the modified Mayo (0 to 9, no global assessment) and the endoscopic subscore used alone for mucosal healing. Two of those have a maximum of 9 and they are not the same 9, so “Mayo 6 of 9” does not identify a patient.
The endoscopic subscore is also where the score disagrees with itself. Schroeder’s original grade 1 includes “mild friability”; the trial wording in current use drops friability from grade 1, and the LUCENT 1 protocol defines its endpoint as a subscore of 0 or 1 “excluding friability”. A friable mucosa is grade 1 under one and grade 2 under the other, which flips its mucosal-healing status. It is also the least reproducible part of the score: scored from colonoscopy video by three expert endoscopists in 67 patients, weighted kappa was 0.80, 0.52 and 0.49 between the three pairs overall but only 0.715, 0.259 and 0.252 restricted to grades 1 and 2 — the grades that decide whether a patient has healed — and 1.0 at grades 0 and 3. UCEIS was developed to address that, and its intraclass correlation in the same study was 0.922. This index scores symptoms, not inflammation. It can be high with a normal mucosa — bile-acid diarrhoea, a stricture, bacterial overgrowth, coexisting irritable bowel syndrome — and low with active endoscopic disease. That mismatch is why treat-to-target moved off symptom indices and onto objective markers. The faecal calprotectin interpreter and the CRP unit converter are what to add when the symptom items and the endoscopy disagree, and the Truelove and Witts criteria rather than this score is what grades an acute severe attack. 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 is the Mayo score definition of remission?
A total of 2 or less AND no individual subscore above 1. Both halves are required, and they are stated together in trial protocols and in ECCO-ESGAR. A total of 2 made up of an endoscopic subscore of 2 with three zeros meets the total and fails the definition, which is the commonest way it is misapplied.
What is the difference between the full, partial and modified Mayo scores?
The full score is all four items, 0 to 12. The partial score drops the endoscopy, 0 to 9. The modified score drops the physician’s global assessment instead, also 0 to 9. The two 9-point versions are not the same 9, so a Mayo score quoted without its version cannot be interpreted.
Is the endoscopic subscore reliable?
Not in the middle of its range. In 67 patients scored from colonoscopy video by three expert endoscopists, weighted kappa between pairs was 0.80, 0.52 and 0.49 overall, 1.0 at grades 0 and 3, and 0.715, 0.259 and 0.252 for grades 1 and 2 alone — the grades that decide mucosal healing are the ones observers agree about least.
Does friability score 1 or 2?
It depends which wording you are using, and the answer changes the patient’s mucosal-healing status. Schroeder’s original grade 1 includes mild friability; the trial wording in current use drops friability from grade 1, putting it at grade 2, and the LUCENT 1 protocol defines endoscopic remission as a subscore of 0 or 1 excluding friability. Both wordings are in print and this page prints both.
Can I use the Mayo score in an acute severe attack?
It was not built for that: it was derived in mildly to moderately active disease, and in acute severe colitis the endoscopy is limited to an unprepared flexible sigmoidoscopy if it is done at all. The instruments for an acute severe attack are Truelove and Witts, a trigger rather than a score, and the day-3 Oxford criteria thereafter.
Related calculators
References
- Pfizer. Statistical Analysis Plan, A3921139 (OCTAVE Open), Appendix 2.1: Mayo scoring system. NCT01470612, clinicaltrials.gov.
- Takeda. Clinical Study Protocol MLN0002-3026 (VARSITY), Sections 5.2.1, 5.2.2 and 9.1.6. NCT02497469, clinicaltrials.gov.
- Belvis Jiménez M, Castro Laria L, Maldonado Pérez B, et al. Index of the Mayo Endoscopy and Ulcerative Colitis Endoscopy Index of Severity: are they equally valid? Rev Esp Enferm Dig. 2020;112(11):821–5.
- Viscido A, Valvano M, Stefanelli G, et al. Systematic review and meta-analysis: the advantage of endoscopic Mayo score 0 over 1 in patients with ulcerative colitis. BMC Gastroenterol. 2022;22(1):92.
- 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
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/