Risk of Seizures Following DTP and MMR Vaccines

J Gordon Millichap
2001 Pediatric Neurology Briefs  
The risk of a first seizure, subsequent seizures, and neurodevelopmental disability following the administration of diphtheria and tetanus toxoids ana whole-cell pertussis (DTP) vaccine and measles, mumps, and rubella (MMR) vaccine was studied by a retrospective review of children's medical records at four health maintenance organizations, including University of Washington, Seattle; and Kaiser Permanente Groups in OR and CA, members of the CDC & P Vaccine Safety Datalink Project. Data were
more » ... ject. Data were collected from more than 600,000 enrolled children (under age 7 years) between 1991 and 1993. Seizures were identified by automated data systems on hospitalizations and clinic visits and by random-sampling of medical records. Simple febrile seizures were defined as short and generalized, and complex febrile seizures occurred more than once in 24 hours, lasted at least 12 minutes or were focal. Nonfebrile seizures due to prior infection or trauma were excluded. The background rate of febrile seizures during the first two years of life was used to calculate the risk attributable to immunization. Following 340,386 DTP and 137,457 MMR vaccinations, 2281 first seizures were identified using automated data, and 716 first seizures from random sampling and chart review of 1094 children. First seizures were febrile in 487 (460 simple, 27 complex), nonfebrile in 137, infantile spasms or neonatal in 36, and other causes in 56. Febrile seizures occurred within 30 days after DTP and MMR vaccines in 42 (5 on the same day as DTP) and 32, respectively. Febrile seizures were recorded in the absence of vaccination in 521 children. Nonfebrile seizures occurred within 30 days after DTP and MMR vaccines in 10 and 3 children, respectively. DTP was associated with a significantly increased risk of febrile seizures on the day of vaccination (relative risk, 5.70; 95% confidence interval, 1.98-16.42). MMR was also associated with increased risk of febrile seizures 8 to 14 days after vaccination (RR 5.7; 95% CI, 1.44-5.55). The estimated numbers of febrile seizures attributable to DTP and MMR vaccination were 6 to 9 and 25 to 34 per 100,000 children, respectively. Of the children with febrile seizures not related to vaccination, 5 percent had developed epilepsy at two year follow-up. Febrile PEDIATRIC NEUROLOGY BRIEFS (ISSN 1043-3155)
doi:10.15844/pedneurbriefs-15-9-1 fatcat:yztwszvujnb4halgwywbfjdnz4