Case Study: Intussusception risk after rotavirus vaccination in US infants

Question 1

Background

Answer 1

• RotaShield, first vaccine for prevention of rotavirus infection in infants
• post-licensure studies in other countries suggested increased risk of intussusception, so FDA requested study to quantify risk among US infants

Question 2

Study Population

Answer 2

613,000 infant years (5-36.9 weeks of age) using medical claims data (healthcare, humana, aetna)

Question 3

Exposure and Outcome

Answer 3

• Vaccination with RotaTeq and RotaRix initially identified by CPT code (validated with EMR)
• cases identified by ICD-9

Question 4

Study design

Answer 4

SCRI (Self controlled risk interval)

• use vaccinated cases with intussusception in pre-specified risk or control window
• two intervals: 7 days and 21 days
• Ho: risk of outcome on average day in risk interval = risk of outcome on average day in control interval

Question 5

Time varying confounder by age

Answer 5

-incorporate offset term into model

Question 6

Conclusion

Answer 6

-RV5 associated with 1.5 excess cases of intussusception per 100,000 recipients of the first dose