| Study characteristics |
| Methods |
Case‐only ecological method. Study to determine if the introduction of MMR vaccine in 1988 increased rates in those populations that were offered the vaccine as infants. |
| Participants |
England population aged between 4 and 18 years between April 1991 and March 2003 (about 11.6 million) |
| Interventions |
Introduction of MMR vaccination (1988) |
| Outcomes |
Emergency hospitalisation for Crohn's disease. Age‐specific ranges were calculated such that rates in population with at least 84% coverage and those in population with coverage below 7% were compared. |
| Funding Source |
Government |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| COEM ‐ case selection |
Unclear risk |
There was insufficient information. |
| COEM ‐ exposure |
Unclear risk |
There was insufficient information. |
| COEM ‐ time trend comparison |
Unclear risk |
There was insufficient information. |
| COEM ‐ comparability |
Unclear risk |
There was insufficient information. |
