title: Incidence of intussusception among infants in a large commercially insured population in the United States.
abstract: BACKGROUND
  To estimate the incidence of intussusception among infants treated in inpatient and emergency department settings during the period preceding the US launch of second-generation rotavirus vaccines.
  
  
  METHODS
  From a large US health insurance claims database, we sampled 100,000 infants aged 1 to 3 months at first diphtheria-tetanus-acellular pertussis vaccination between 2001 and 2005. Potential intussusception cases were identified on the basis of claims and were confirmed by medical record review. Incidence rates (IRs) and 95% confidence intervals (CIs) were estimated based on follow-up from first diphtheria-tetanus-acellular pertussis dose to up to 1 year of age, and within 21, 30, and 60 days after each dose.
  
  
  RESULTS
  The IR of intussusception in the first year of life was 0.33/1000 person-years based on 22 confirmed cases (95% CI: 0.21-0.50/1000 person-years). The age-specific incidence peaked among infants aged 5 months (IR: 0.82/1000 person-years; 95% CI: 0.30-1.78/1000 person-years). During the 21, 30, and 60 days following any dose, the incidence per 1000 person-years was 0.27, 0.24, and 0.33, respectively.
  
  
  CONCLUSIONS
  The rates described in this study can serve as a benchmark for comparison with incidences observed after the introduction of the second-generation rotavirus vaccines.
authors.affiliation: Epidemiology, OptumInsight, Waltham, MA 02451, USA.
authors.forename: Patricia Mona
authors.initials: PM
authors.lastname: Eng
authors.forename: T Christopher
authors.initials: TC
authors.lastname: Mast
authors.forename: Jeanne
authors.initials: J
authors.lastname: Loughlin
authors.forename: C Robin
authors.initials: CR
authors.lastname: Clifford
authors.forename: Judy
authors.initials: J
authors.lastname: Wong
authors.forename: John D
authors.initials: JD
authors.lastname: Seeger
mesh_terms: D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007443:Intussusception / Q000453:epidemiology*; D008297:Male; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology