OBJECTIVES: To identify the relationship of physician reported risk factors to the incidence of hospitalizations after the initiation of Palivizumab (Synagis TM) therapy for first season prophylaxis to respiratory syncytial virus (RSV). METHODS: Participants from Caremark's specialty pharmacy database who initiated Palivizumab therapy for the 2001-02 season were analyzed on physician reported risk factors prior to therapy initiation for one large payer. These risk factors include, respiratory related hospitalizations, older siblings, multiple births, exposure to smoke, chronic illness diagnosis, medical treatment, daycare and unspecified risk. We assessed the proportion of risk factors within the population at the initiation of therapy for first season infant exposure. The relationship between these risk factors and post-therapy initiation hospitalization rates will be assessed using multivariate analysis. The study period was for participants born after 01 April 2001. RESULTS: 410 participants (age=156 +/- 63 days) who presented prescriptions for Palivizumab through Caremark's Specialty Pharmacy for the 2001-2002 RSV season were analyzed. On average, infants had 1.23 +/- 1.05 risk factors. We identified 4.15% of the infants had a reported respiratory hospitalization prior to initiation of Palivizumab therapy. Other risk factors prior to therapy initiation were distributed as follows: 33.9% Older Siblings, 30.24% Multiple Births, 7.07% Exposure to Smoke, 5.37% Chronic Illness Diagnosis, 22.2% Medical Treatment, 10.0% Daycare Exposure, and 14.39% Unspecified Risk. Post therapy initiation hospitalization rates for the 2001-2002 RSV season are currently being collected and results of the multivariate analysis will be presented. CONCLUSION: A priori variables to direct and optimize therapeutic management of at-risk RSV infant populations are essential. These findings on hospitalization rates associated with physician reported risk factors would support the decision making of both pharmacy and provider organizations.