Trends in Rate of Seizure-Associated Hospitalizations Among Children <5 Years Old Before and After Rotavirus Vaccine Introduction in the United Sates, 2000-2013

Abstract

Background: Rotavirus is a common cause of acute gastroenteritis and has also been associated with generalized tonic-clonic afebrile seizures. Since rotavirus vaccine introduction, hospitalizations for treatment of acute gastroenteritis have decreased. We assess whether there has been an associated decrease in seizure-associated hospitalizations.

Methods: We used discharge codes to abstract data on seizure hospitalizations among children <5 years old from the State Inpatient Databases of the Healthcare Cost and Utilization Project. We compared seizure hospitalization rates before and after vaccine introduction, using Poisson regression, stratifying by age and by month and year of admission. We performed a time-series analysis with negative binomial models, constructed using prevaccine data from 2000 to 2006 and controlling for admission month and year.

Results: We examined 962899 seizure hospitalizations among children <5 years old during 2000-2013. Seizure rates after vaccine introduction were lower than those before vaccine introduction by 1%-8%, and rate ratios decreased over time. Time-series analyses demonstrated a decrease in the number of seizure-coded hospitalizations in 2012 and 2013, with notable decreases in children 12-17 months and 18-23 months.

Conclusions: Our analysis provides evidence for a decrease in seizure hospitalizations following rotavirus vaccine introduction in the United States, with the greatest impact in age groups with a high rotavirus-associated disease burden and during rotavirus infection season.

Keywords: Rotavirus; seizures; vaccine.

Figure 1.

Rate ratios and 95% confidence intervals for seizure hospitalizations before (during 2000–2006) and after (during 2008–2013) rotavirus vaccine introduction, by month, year, and age group. The shaded area indicates the historical peak rotavirus season of January–June. Poisson models were used to generate estimates, with population sizes drawn from census estimates. Seizure hospitalization data are from the State Inpatient Databases of the Healthcare Cost and Utilization Project (reference) and include 26 states: Arizona, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Iowa, Illinois, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Missouri, North Carolina, New Jersey, New York, Oregon, South Carolina, Tennessee, Texas, Utah, Washington, Wisconsin, and West Virginia.

Figure 2.

Estimates of predicted seizure hospitalization rates as compared to observed seizure hospitalization rates, 2000–2013, by month, year, and age group. The light gray shaded area indicates the historical rotavirus season of January–June. The dashed line indicates the estimated seizure rates, by month and year. The dark gray ribbon indicates the 95% confidence bounds for the estimated rates. The black squares indicate observed seizure rates, by month and year. Estimates were generated using predicted values from the results of negative binomial models run on age-stratified data from 2000 to 2006 and controlling for month and year. Population sizes were drawn from census estimates. Seizure hospitalization data are from the State Inpatient Databases of the Healthcare Cost and Utilization Project (reference) and include 26 states: Arizona, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Iowa, Illinois, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Missouri, North Carolina, New Jersey, New York, Oregon, South Carolina, Tennessee, Texas, Utah, Washington, Wisconsin, and West Virginia.