Cost-effectiveness of palivizumab in infancy

Updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for respiratory syncytial virus infection

Guidance from the American Academy of Pediatrics (AAP) for the use of palivizumab prophylaxis against respiratory syncytial virus (RSV) was first published in a policy statement in 1998. Guidance initially was based on the result from a single randomized, placebo-controlled clinical trial conducted in 1996-1997 describing an overall reduction in RSV hospitalization rate from 10.6% among placebo recipients to 4.8% among children who received prophylaxis. The results of a second randomized, placebo-controlled trial of children with hemodynamically significant heart disease were published in 2003 and revealed a reduction in RSV hospitalization rate from 9.7% in control subjects to 5.3% among prophylaxis recipients. Because no additional controlled trials regarding efficacy were published, AAP guidance has been updated periodically to reflect the most recent literature regarding children at greatest risk of severe disease. Since the last update in 2012, new data have become available regarding the seasonality of RSV circulation, palivizumab pharmacokinetics, the changing incidence of bronchiolitis hospitalizations, the effects of gestational age and other risk factors on RSV hospitalization rates, the mortality of children hospitalized with RSV infection, and the effect of prophylaxis on wheezing and palivizumab-resistant RSV isolates. These data enable further refinement of AAP guidance to most clearly focus on those children at greatest risk.

Glycan variants of a respiratory syncytial virus antibody with enhanced effector function and in vivo efficacy

Respiratory syncytial virus (RSV) can cause devastating lower respiratory tract infections in preterm infants or when other serious health problems are present. Immunoprophylaxis with palivizumab (Synagis), a humanized IgG1 mAb, is the current standard of care for preventing RSV infection in at-risk neonates. We have explored the contribution of effector function to palivizumab efficacy using a plant-based expression system to produce palivizumab N-glycan structure variants with high homogeneity on different antibody isotypes. We compared these isotype and N-glycoform variants with commercially available palivizumab with respect to both in vitro receptor and C1q binding and in vivo efficacy. Whereas the affinity for antigen and neutralization activity of each variant were indistinguishable from those of palivizumab, their Fcγ receptor binding profiles were very different, which was reflected in either a reduced or enhanced ability to influence the RSV lung titer in challenged cotton rats. Enhanced Fcγ receptor binding was associated with reduced viral lung titers compared with palivizumab, whereas abrogation of receptor binding led to a drastic reduction in efficacy. The results support the hypotheses that classic antibody neutralization is a minor component of efficacy by palivizumab in the cotton rat and that antibody-dependent cell-mediated cytotoxicity activity can significantly enhance the efficacy of this antiviral mAb.

Monoclonal antibody for reducing the risk of respiratory syncytial virus infection in children

BACKGROUND

Respiratory syncytial virus (RSV) is one of the most important viral pathogens causing acute respiratory infections in children. It results in about 3.4 million hospitalisations annually in children under five. Palivizumab is an anti-RSV monoclonal antibody, administered intramuscularly at a dose of 15 mg/kg once every 30 days. The efficacy and safety of palivizumab has been evaluated in multicentre, randomised controlled trials (RCTs) and a large number of economic evaluations (EEs) have tested its cost-effectiveness.

OBJECTIVES

To assess the effectiveness and safety of palivizumab prophylaxis compared with placebo, or another type of prophylaxis, in reducing the risk of complications (hospitalisation due to RSV infection) in high-risk infants and children. To assess the cost-effectiveness (or cost-utility) of palivizumab prophylaxis compared with no prophylaxis in infants and children in different risk groups.

SEARCH METHODS

We searched CENTRAL 2012, Issue 7, MEDLINE (1996 to July week 4, 2012), EMBASE (1996 to August 2012), CINAHL (1996 to August 2012) and LILACS (1996 to August 2012) for studies of effectiveness and safety. We searched the NHS Economic Evaluations Database (NHS EED 2012, Issue 4), Health Economics Evaluations Database (HEED, 9 August 2012) and Paediatric Economic Database Evaluations (PEDE, 1980 to 2009), MEDLINE (1996 to July week 4, 2012) and EMBASE (1996 to August 2012) for economic evaluations.

SELECTION CRITERIA

We included RCTs comparing palivizumab prophylaxis with a placebo, no prophylaxis or another type of prophylaxis in preventing serious lower respiratory tract disease caused by RSV in paediatric patients at high risk. We included cost-effectiveness analyses and cost-utility analyses comparing palivizumab prophylaxis with no prophylaxis.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed risk of bias for the included studies and extracted data for both the RCTs and EEs. We calculated risk ratios (RRs) and their associated 95% confidence intervals (CIs) for dichotomous outcomes and for adverse events (AEs). We provided a narrative summary of results for continuous outcomes, due to missing data on standard deviations. We performed fixed-effect meta-analyses for the estimation of pooled effects whenever there was no indication of heterogeneity between included RCTs. We summarised the results reported in included EEs, such as incremental costs, incremental effectiveness, and incremental cost-effectiveness and/or cost-utility ratios (ICERs), and we calculated ICER present values in 2011 Euros for all studies.

MAIN RESULTS

Of the seven available RCTs, three compared palivizumab with a placebo in a total of 2831 patients, and four compared palivizumab with motavizumab in a total of 8265 patients. All RCTs were sponsored by the drug manufacturing company. The overall quality of RCTs was good, but for most of the outcomes assessed only data from two studies contributed to the analysis. Palivizumab prophylaxis was associated with a statistically significant reduction in RSV hospitalisations (RR 0.49, 95% CI 0.37 to 0.64) when compared to placebo. When compared to motavizumab, palivizumab recipients showed a non-significant increase in the risk of RSV hospitalisations (RR 1.36, 95% CI 0.97 to 1.90). In both cases, the proportion of children with any AE or any AE related to the study drug was similar between the two groups.In terms of economic evidence, we included 34 studies that reported cost-effectiveness and/or cost-utility data for palivizumab prophylaxis compared with no prophylaxis, in high-risk children with different underlying medical conditions. The overall quality of EEs was good, but the variations in modelling approaches were considerable across the studies, leading to big differences in cost-effectiveness results. The cost-effectiveness of palivizumab prophylaxis depends on the consumption of resources taken into account by the study authors; and on the cost-effectiveness threshold set by the healthcare sector in each country.

AUTHORS' CONCLUSIONS

There is evidence that palivizumab prophylaxis is effective in reducing the frequency of hospitalisations due to RSV infection, i.e. in reducing the incidence of serious lower respiratory tract RSV disease in children with chronic lung disease, congenital heart disease or those born preterm.Results from economic evaluations of palivizumab prophylaxis are inconsistent, implying that economic findings must be interpreted with caution. ICER values varied considerably across studies, from highly cost-effective to not cost-effective. The availability of low-cost palivizumab would reduce its inequitable distribution, so that RSV prophylaxis would be available to the poorest countries where children are at greatest risk.

Palivizumab in preventing respiratory syncytial virus-related hospitalization in high-risk infants

Respiratory syncytial virus (RSV) causes seasonal epidemics (winter or wet-season) of serious lower respiratory tract infections in young infants with subsequent increased frequency of recurrent wheezing during early childhood. Palivizumab is a humanized monoclonal antibody that provides immunoprophylaxis against RSV when administered monthly over the RSV season. It significantly reduced hospitalizations in high-risk infants including preterm infants with and without bronchopulmonary dysplasia and infants with hemodynamically significant congenital heart disease. Since its license in 1998, approximately 36 methodologically different economic studies have been performed to prove cost-effectiveness of the product. The majority of cost-effectiveness analyses revealed costs of palivizumab exceeding anticipated savings from reduced RSV hospitalizations. A minority of studies performed cost-effectiveness analyses using incremental cost-effectiveness ratios as costs per quality-adjusted life-year gained. The wide variability in the results of economic studies with estimates ranging from cost savings to incremental costs of a high order of magnitude with its use is discussed, in the light of the continuing burden of RSV disease, the limited treatment modalities, and the continuing research for a vaccine.