Authors' responses in response to the letter from Ambrose.

Abstract

We appreciate the opportunity to comment on the issues raised by an AstraZeneca employee regarding the revised American Academy of Pediatrics (AAP) Guidance on the use of palivizumab for respiratory syncytial virus (RSV) prophylaxis. First, we agree preterm infants experience an RSV hospitalization rate that increases with decreasing gestational age. The critical question is, “How great is the increase in risk for preterm infants relative to term infants?” In the prospective study of 132 000 infants by Hall et al1 and reproduced in Table 1 of the newly published AAP Technical Report,2 the risk of RSV hospitalization over a 6-month season for infants born at ≥37 weeks is 5.3 per 1000 (95% confidence interval [CI], 4.9–5.8). Corresponding rates for infants with gestational age ≥35, 32–34, 29–31, and <29 weeks were 5.1 (95% CI, 4.7–5.5), 6.9 (95% CI, 4.3–10.1), 6.3 (95% CI, 2.0–12.4), and 19.3 (95% CI, 8.4–34.0) per 1000, resulting in nonsignificant differences for all levels of prematurity compared with term infants, except for infants born at <29 weeks, who show a recognizable spike in hospitalization rates. In this report, the increase in risk of hospitalization is ∼1 more RSV hospitalization for every 1000 preterm births. Two other studies discussed in the AAP Technical Report and performed in the preprophylaxis era show a similar very small increase in risk of RSV hospitalization among preterm infants relative to full-term infants. Second, AAP Clinical Practice Guidelines regarding the diagnosis …