| Study characteristics |
| Methods |
Retrospective cohort study ‐ USA ‐ data from Vaccine Safety Datalink: Group Health Cooperative (Washington state), Kaiser Permanente Colorado, Kaiser Permanente Northwest (Oregon), Harvard Pilgrim Health Care (Massachusetts), HealthPartners (Minnesota), Northern California Kaiser Permanente, and Marshfield Clinic (Wisconsin). Linked to cb‐Klein 2010
|
| Participants |
Children aged 48 to 83 months (2 to 7 years old) who were members of the 7 participating VSD sites between January 2000 through October 2008 and who received MMRV; separately administered, same‐day MMR+V; or MMR or V administered alone were eligible for study inclusion. |
| Interventions |
MMRV (Merck & Co)
MMR (Merck & Co Inc, West Point, PA) + V (Merck & Co) |
| Outcomes |
Postvaccination seizure event as the first instance during the 42 days after a measles‐ or varicella‐containing vaccine of ICD‐9 codes 345* (epilepsy) or 780.3* (convulsion) in the emergency department or hospital |
| Funding Source |
Government |
| Notes |
Conclusion: this study provides reassurance that MMRV and MMR+V were not associated with increased risk of febrile seizures among 4‐ to 6‐year‐olds. We can rule out with 95% confidence a risk greater than 1 febrile seizure per 15,500 MMRV doses and 1 per 18,000 MMR+V doses. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| PCS/RCS ‐ exposed cohort selection |
Low risk |
Adequate ‐ registry Kaiser Permanente ‐ representative of exposed |
| PCS/RCS ‐ non‐exposed cohort selection |
Low risk |
Adequate ‐ drawn from the same community |
| PCS/RCS ‐ comparability |
Low risk |
Adequate ‐ adjusted for age group Vaccine Safety Datalink sites respiratory virus season |
| PCS/RCS ‐ assessment of outcome |
Low risk |
Adequate ‐ hospital record with blind assessment |
| Summary Risk of Bias assessment |
Low risk |
Plausible bias is unlikely to have seriously altered the results. |
