Abstract 1592

Background: In the IMpact clinical evaluation of palivizumab (Synagis™), an RSV-specific monoclonal antibody (mAB), hospitalization for lower respiratory RSV infection was reduced 55% among prophylaxed vs. non-prophylaxed infants at risk. To assess potential for related cost savings and the value of prophylaxis, costs for protection and infection should be compared, including RSV mAb-related expenses and the costs for in-patient and out-patient resources to treat infections.

Objective: To compare expected medical charges for prophylaxed infants vs. non-prophylaxed infants during an RSV season, a payer-perspective pharmacoeconomic study was conducted using a decision-analytic model populated with data from the contemporary medical literature. The model depicts in-patient and out-patient care.

Methodology: Probabilities for RSV-related hospitalizations for prophylaxed and non-prophylaxed infants were abstracted from the IMpact, PREVENT, and NIAID studies as well as epidemiologic assessments. Components of in-patient and out-patient care were identified through examinations of hospital records, reviews of published literature, and conclusions with expert clinicians. Charges related to prophylaxis and medical management of infection were abstracted from hospital billing records and public sources. Appropriate charges were applied to decision tree branches and multiplied by in-line probabilities for outcomes. Products at terminal nodes were summed to calculate total expected charges for prophylaxed and non-prophylaxed infants.

Results: Adjusted seasonal hospitalization rates for RSV-infected infants have been cited: 10.6% (IMpact.Peds. 1998;102), 12.3% (HER), 13.5% (PREVENT.Peds. 1997;99), 20.7% (Emond. Amb Child Health. 1997;3), 22.4% (NIAID.Peds. 1995;95), 36.1% (Cunningham. Peds. 1991;88), and 42.6% (Yuksel. Arch Peds Adol Med. 1994;148). Likewise, hospital charges for RSV-infected infants have been reported: $19,190 (HER) $27,101 (low, Oelburg. Neonat Intens Care. 1998), $77,666 (Langley.J Peds. 1997;131), and $166,375 (high, Oelburg.Neonat Intens Care. 1998). Based on these figures, total expected charge per patient (average total charge for all infants including outpatient charges) from model calculations, range from $2,065 (non-prophylaxed) and $4,945 (prophylaxed) to $70,896 (non-prophylaxed) and $31,789 (prophylaxed).

Conclusion: A range of expected incremental charges per patient of $2,880 ($4,945 minus $2,065) to an expected savings per patient of $39,107 ($70,896 minus $31,789) will result from the widespread clinical use of RSV mAb for infants at risk. Costs and benefits relate to hospital charges and/or RSV hospitalization rates, both of which vary by season and region.

Grantor: Research funded through an unrestricted grant from MedImmune, Inc.