Sociodemographic and dietary risk factors for natural infant intussusception in the United States.
BACKGROUND
In 1999, a US case-control study demonstrated a strong association between intussusception and a rotavirus vaccine (Rotashield). However, because most (87%) cases were not temporally associated with vaccination, we reanalyzed these data to assess risk factors for intussusception cases unrelated to Rotashield.


METHODS
Case-patients were infants with intussusception between November 1998 and June 1999. Controls were matched by age and hospital of birth. Sociodemographic and feeding practice data were collected through parent and provider interviews. Conditional logistic regression was used to identify risk factors for intussusception, controlling for exposure to Rotashield <21 days before intussusception.


RESULTS
Four hundred twenty-nine cases and 1763 controls were enrolled. Among case-patients, 372 (87%) had not received Rotashield within 21 days before intussusception. After adjusting for recent Rotashield administration, factors associated with intussusception included male sex (odds ratio [OR] 1.7; 95% confidence interval [CI] 1.3-2.2), Hispanic (OR 2.1; 95% CI 1.4-3.2) or black (OR 1.8; 95% CI 1.2-2.7) race/ethnicity, and Medicaid enrollment (OR 1.5; 95% CI 1.1-2.0). Feeding practices modified the risk of intussusception. Interaction was found between introduction of solid food (ISF) and type of formula consumption. Using breast milk as the referent group, infants with ISF for at least 5 weeks who consumed soy milk-based formula had a lower risk (OR 0.26; 95% CI 0.1-0.7) and infants without ISF who consumed cow's-milk formula had an increased risk (OR 2.33; 95% CI 1.4-3.9).


CONCLUSIONS
Risk of intussusception among US infants varies based on sociodemographic characteristics and feeding patterns.
Johnson
Brian
B
National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Gargiullo
Paul
P
Murphy
Trudy V
TV
Parashar
Umesh D
UD
Patel
Manish M
MM
D044383:Black People / Q000706:statistics & numerical data; D016022:Case-Control Studies; D015984:Causality; D004032:Diet / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000009:adverse effects / Q000706:statistics & numerical data; D041943:Infant Formula / Q000706:statistics & numerical data; D007443:Intussusception / Q000453:epidemiology*; D008297:Male; D008484:Medicaid / Q000706:statistics & numerical data; D016017:Odds Ratio; D012307:Risk Factors; D017678:Sex Distribution; D012959:Socioeconomic Factors; D041942:Soy Milk / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology; D001741:Black or African American