title: Effect of an older sibling and birth interval on the risk of childhood injury.
abstract: OBJECTIVE
  Certain family structures have been identified as putting children at high risk for injury. To further define children at highest risk, we set out to explore the effect of an older sibling and birth interval on the risk of injury related hospital admission or death.
  
  
  METHODS
  Data were analyzed using a case-control design. Cases and controls were identified by linking longitudinal birth data from Washington state (1989-96) to death certificate records and hospital discharge data obtained from the Washington State Comprehensive Hospital Abstract Reporting System and frequency matched in a 1:2 ratio on year of birth. Cases consisted of singleton children 6 years of age or younger who were hospitalized or died as a result of injury during the years 1989-96. Multivariate logistic regression was used to identify and adjust for confounding variables.
  
  
  RESULTS
  There were 3145 cases and 8371 controls. The adjusted odds ratio for injury in children with an older sibling was 1.50 (95% confidence interval 1.37 to 1.65). The effect was greatest in children under 2 years of age, and in those with a birth interval of less than two years. As the number of older siblings increased, so did the risk of injury, with the highest risk in children with three or more older siblings.
  
  
  CONCLUSIONS
  These data suggest that the presence of an older sibling is associated with an increased risk of injury. The risk is highest in those with very short birth intervals. Potential mechanisms for this increased risk may relate to inadequate parental supervision. Pediatricians and other care providers need to be alert to these identifiable risk factors and then direct preventive strategies, such as home visits and educational programs, toward these families.
authors.affiliation: Harborview Injury Prevention and Research Center, Department of Surgery, Seattle, Washington 98104, USA. anathens@u.washington.edu
authors.forename: A B
authors.initials: AB
authors.lastname: Nathens
authors.forename: M J
authors.initials: MJ
authors.lastname: Neff
authors.forename: C H
authors.initials: CH
authors.lastname: Goss
authors.forename: R V
authors.initials: RV
authors.lastname: Maier
authors.forename: F P
authors.initials: FP
authors.lastname: Rivara
mesh_terms: D001719:Birth Certificates; D001721:Birth Intervals; D016022:Case-Control Studies; D002648:Child; D002669:Child Welfare / Q000706:statistics & numerical data*; D002675:Child, Preschool; D015986:Confounding Factors, Epidemiologic; D003644:Death Certificates; D004522:Educational Status; D005191:Family Characteristics; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D009679:Nuclear Family; D016487:Parenting; D012307:Risk Factors; D012959:Socioeconomic Factors; D014861:Washington / Q000453:epidemiology; D014947:Wounds and Injuries / Q000209:etiology* / Q000401:mortality* / Q000517:prevention & control