Disease activity will be defined through the following modalities
| Crohn’s disease | UC | Pouchitis | |
| Active disease (clinical scores) | Crohn’s Disease Activity Index (CDAI)24 >150 Harvey Bradshaw Index (HBI)25 >5 | MAYO* score for Ulcerative Colitis Index26 >2 | Pouchitis Disease Activity Index27 >4 |
| Active disease (endoscopic scores) | Simple Endoscopic Score for Crohn’s Disease (SES CD)28 >3 Crohn’s Disease Index of Severity (CDEIS)29 >3 | MAYO score >1 Ulcerative Colitis Endoscopic Index of Severity (UCEIS)30 >2 | |
| Active disease (biochemical scores) | C reactive protein (CRP)31 >5 mg/L, faecal calprotectin (FCP)31 >250 µg/g | CRP >5 mg/L, FCP >250 µg/g | |
| Remission (clinical scores) | CDAI <150, HBI <4 | MAYO score <2 and no individual subscore >1 | |
| Remission (endoscopic scores) | SES CD: 0–2 CDEIS <3 | UCEIS <1 MAYO score ≤1 | |
| Remission (biochemical scores) | CRP <5, FCP <250 | CRP <5, FCP <250 | |
| Response (clinical scores) | CDAI-70, CDAI-10032
HBI drop by 3 or more points33 | Reduction of baseline MAYO score by ≥3 points and a decrease of 30% from the baseline score with a decrease of a least one point on the rectal bleeding subscale or an absolute rectal bleeding score of 0 or 1 (21) | |
| Response (endoscopic scores) | 50% drop in the SES-CD34 | Decrease in MAYO endoscopic score ≥1 grade or a decrease in UCEIS ≥2 points35 | |
| Response (biochemical scores) | This is not defined |
Note: For studies defining these indices with other methods, they will not be included in main analysis, but will be included in wider sensitivity analysis.
MAYO score: The Mayo Clinic score is a tool used to evaluate the severity of ulcerative colitis (UC) in patients. It is based on a patient's clinical symptoms, endoscopic findings, and laboratory results. The score ranges from 0 to 12, with higher scores indicating more severe disease. The Mayo score takes into account factors such as the extent of colon involvement, the presence of ulcers, and the degree of inflammation seen on endoscopy. It is used to determine the severity of the disease, to monitor the response to treatment, and to guide decisions about therapy.
*MAYO and HBI score denotes derivations of the scores like modified MAYO, partial MAYO score or rectal bleeding and stool frequency UC patient reported outcomes and abdominal pain and stool frequency CD patient-reported outcomes. Specific definitions for active disease for these derivations are not described here.
UC, ulcerative colitis.