bb‐Davis 2001.

Study characteristics
Methods	Case‐control study
Participants	Potential cases were selected by ICD‐9 codes specific for Crohn's disease, ulcerative colitis, and idiopathic proctocolitis (ICD‐9 codes 555 and 556) in the computerised databases. Case and control selection was limited to people born after 1979. To be included, cases and controls had to be enrolled from age 6 months up to the index date (the first date of disease diagnosis or symptoms for cases) or reference date for controls. Vaccine Safety Datalink Project (VSDP), children enrolled from the 6th month Cases: cases of definite IBD (VSDP, N = 142) Controls: children matched for sex, HMO, and birth year (N = 432)
Interventions	Exposure to MMR or other measles‐containing vaccines (MCV)
Outcomes	Exposure to MMR or MCV considering any time, within 2 to 4 months, within 6 months
Funding Source	Government
Notes	There are no details of vaccine type, i.e. manufacturer, strains, dosage, etc.
Risk of bias
Bias	Authors' judgement	Support for judgement
CCS ‐ case selection	Low risk	Adequate ‐ secure record
CCS ‐ control selection	Unclear risk	Adequate ‐ community
CCS ‐ comparability	Unclear risk	Probable residual confounding ‐ matched for sex, HMO, and birth year
CCS ‐ exposures	Unclear risk	Probably adequate ‐ secure record, but there are no details of vaccine type, i.e. manufacturer, strains, dosage, etc.
Summary Risk of Bias assessment	Unclear risk	We had concerns regarding at least 1 domain such that some doubt is raised about the results.