| Study characteristics |
| Methods |
Case‐control study |
| Participants |
Case of hay fever were children with diagnostic codes and/or treatment for hay fever (see bb‐Bremner 2005), after 2 years of age. Control was child that matched for general practice, sex, birth month, and follow‐up of control "to at least date of diagnosis case". |
| Interventions |
MMR II |
| Outcomes |
Incidence of hay fever following MMR exposure was compared inside versus outside the grass pollen season. |
| Funding Source |
Pharmaceutical industry |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| CCS ‐ case selection |
Low risk |
Adequate ‐ secure record ‐ representative series of case ‐ population based |
| CCS ‐ control selection |
Low risk |
Adequate ‐ community control |
| CCS ‐ comparability |
Low risk |
Adequate ‐ matching: practice ID, age, sex, and index date |
| CCS ‐ exposures |
Low risk |
Adequate ‐ secure record |
| Summary Risk of Bias assessment |
Low risk |
Plausible bias is unlikely to have seriously altered the results. |
