Background: Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections and hospitalization in infants. Palivizumab is currently the only available agent for prevention of RSV infection in high-risk infants. This high-cost injectable requires monthly dosing during the RSV season. Compliance with the injection schedule is important in the prevention of RSV infection and respiratory complications. Managed care organizations have an interest in the relationship between compliance with the palivizumab dosing schedule and respiratory-related medical outcomes such as emergency room (ER) visits, physician office visits, and hospitalizations.
Objective: To evaluate respiratory-related medical outcomes and cost for infants who were prescribed and received palivizumab in accordance with the dosing schedule recommended by the American Academy of Pediatrics (AAP) in 2006 versus those who did not.
Methods: A retrospective claims analysis was conducted to assess the relationship between compliance with the palivizumab dosing schedule and respiratory-related medical visits and costs in a western Pennsylvania managed care organization composed of approximately 307,000 commercial and 92,000 Medicaid members. De-identified pharmacy and medical claims data were extracted for infants (0-24 months) who met prior authorization criteria and who received at least 1 dose of palivizumab during the 2006-2007 RSV season (October 15, 2006, to April 15, 2007). Patient compliance was based on (a) starting palivizumab on time, (b) receiving the expected number of injections, and (c) no more than a 37-day gap between palivizumab claims. Medical utilization (physician office visits, ER visits, and hospital admissions) was analyzed by comparing medical services (with respiratory-related ICD-9-CM codes) for the compliant versus noncompliant groups. Net health plan costs (after subtraction of member cost share) were compared for compliant versus noncompliant groups for (a) palivizumab-only pharmacy cost; (b) the cost of RSV-related medical services; and (c) the cost of all respiratory-related medical services, excluding those provided during the inpatient newborn stay. The associations between compliance and other patient variables were assessed using the Mann-Whitney U test for nonparametric data and Pearson chi-square or Fisher's Exact tests for categorical data.
Results: Of the 245 infants who received palivizumab during the 2006- 2007 RSV season, 151 (61.6%) were first-season recipients of palivizumab, and 131 (53.5%) were male; 145 (59.2%) belonged to a Medicaid benefit plan, and 100 (40.8%) belonged to a commercial benefit plan; and 73 (29.8%) were deemed to be compliant with the 2006 AAP recommended palivizumab dosing schedule. Fourteen (19.2%) of compliant infants had at least 1 respiratory-related hospital admission compared with 37 (21.5%) of noncompliant infants (P = 0.734). The proportions of infants with at least 1 respiratory-related physician office visit were also similar for the 2 groups, 60.3% (n = 44) for compliant infants versus 64.5% (n = 111) for noncompliant infants (P = 0.564). There was a significant difference in the proportion of infants with at least 1 respiratory-related ER visit, 15.1% (n = 11) of compliant infants versus 28.5% (n = 49) of noncompliant infants (P = 0.034), but there were no RSV-related ER visits in either group and no significant differences between the groups in the proportion with at least 1 RSV-related office visit (9.6% for compliant infants vs. 5.8% for noncompliant infants, P = 0.284). RSV-related hospitalization occurred in 0 (0.0%) compliant and 2 (1.2%) noncompliant infants (P = 1.000). Compliant infants had significantly higher median per patient palivizumab pharmacy costs ($10,416) compared with noncompliant infants ($7,605, P = 0.011). However, median total (palivizumab and respiratory-related medical) costs for the 2 groups did not significantly differ (P = 0.189).
Conclusion: About 30% of the infants who received palivizumab during the 2006-2007 RSV season were compliant with dosing recommendations. Compliance was associated with a lower proportion of infants with at least 1 respiratory-related ER visit but not with any other study outcome, including the proportion of infants with at least 1 hospital admission or physician visit or any measure of RSV-related use. Median palivizumab per patient costs were higher for the compliant group, but there was no significant between-group difference in total median per patient cost (palivizumab drug plus respiratory-related medical cost).