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

Association between respiratory syncytial viral disease and the subsequent risk of the first episode of severe asthma in different subgroups of high-risk Australian children: a whole-of-population-based cohort study

OBJECTIVE

To determine the contribution of respiratory syncytial virus (RSV) to the subsequent development of severe asthma in different subgroups of children at risk of severe RSV disease.

SETTINGS

The study was conducted in New South Wales (NSW), Australia.

PARTICIPANTS

The study comprised all children born in NSW between 2000 and 2010 with complete follow-up till 31 December 2011. The cohort was divided into three subgroups: (1) non-Indigenous high-risk children: non-Indigenous children born preterm or born with a low birth weight; (2) Indigenous children: children of mothers whose Indigenous status was recorded as Aboriginal and/or Torres Strait Islander and (3) non-Indigenous standard risk children: all other non-Indigenous term children.

PRIMARY OUTCOME MEASURE

Risk of development of severe asthma in different subgroups of children who had RSV hospitalisation in the first 2 years of life compared with those who did not.

DESIGN

We performed a retrospective cohort analysis using population-based linked administrative data. Extended Cox model was used to determine HR and 95% CI around the HR for first asthma hospitalisation in different subgroups of children.

RESULTS

The cohort comprised 847 516 children born between 2000 and 2010. In the adjusted Cox model, the HR of first asthma hospitalisation was higher and comparable across all subgroups of children who had RSV hospitalisation compared with those who did not. The HR (95% CI) was highest in children aged 2-3 years; 4.3 (95% CI 3.8 to 4.9) for high-risk, 4.0 (95% CI 3.3 to 4.8) for Indigenous and 3.9 (95% CI 3.7 to 4.1) for non-Indigenous standard risk children. This risk persisted beyond 7 years of age.

CONCLUSION

This large study confirms a comparable increased risk of first asthma hospitalisation following RSV disease in the first 2 years of life across different subgroups children at risk.

Product review on the monoclonal antibody palivizumab for prevention of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) accounts for about 20% of all respiratory infections in children below the age of 5 y. It is associated with up to 63% of all acute respiratory infections and up to 81% of all viral lower respiratory tract infections causing hospitalization in infants and young children. RSV leads to seasonal epidemics between November and April in the northern hemisphere. Most severe infections (RSV accounts for 50 to 80% of all cause bronchiolitis) affect infants younger than 6 months of age and high-risk infants including those born preterm with or without bronchopulmonary dysplasia and those with hemodynamically significant congenital heart disease up to an age of 24 months. Palivizumab, a highly potent RSV-neutralizing monoclonal antibody (Mab), has been licensed in 1998 for prophylactic use to prevent RSV associated hospitalizations in high-risk infants. This Mab is given by monthly intramuscular injection at a dose of 15 mg/kg over the RSV season (up to 5 times). Palivizumab proved to be safe and well-tolerated in this population. Concerns have been raised regarding cost-effectiveness of palivizumab and thus, palivizumab prophylaxis is mainly limited to selected high-risk infants for the first RSV season. Long-lasting Mabs will be the next future approach in the prophylaxis of RSV hospitalization until a vaccine is developed.

Risk factors associated with RSV hospitalisation in the first 2 years of life, among different subgroups of children in NSW: a whole-of-population-based cohort study

BACKGROUND

Data on risk factors for respiratory syncytial virus (RSV)-associated hospitalisation in Australian children may be informative for preventive measures.

METHODS

A whole-of-population-based study was conducted to identify comparable risk factors for RSV hospitalisation in different subgroups of children aged <2 years in New South Wales. The cohort was divided into Indigenous children and high-risk and standard risk non-Indigenous children. Data on risk factors were obtained from the Perinatal Data Collection. RSV hospitalisations were ascertained from the Admitted Patient Data Collection. Adjusted HRs were calculated for each subgroup. Population-attributable risk associated with risk factors was estimated.

RESULTS

Four factors were associated with increased risk of RSV hospitalisation: maternal smoking during pregnancy, male sex, multiparity and birth during the first half of the RSV season. Increase in relative socioeconomic advantage was associated with decreased risk of hospitalisation. Among high and standard risk non-Indigenous children, the hazard was approximately double for children born to multiparous women compared to those born to primiparous women and among Indigenous children the hazard was approximately double among those born during the first half of the RSV season. Maternal smoking during pregnancy was associated with a 26-45% increased risk across subgroups and accounted for 17% (95% CI 9.3% to 24%) of RSV hospitalisations in Indigenous children, 5% (95% CI 2.5% to 8%) in high-risk and 6% (95% 5% to 7%) in standard risk non-Indigenous children.

DISCUSSION

Promoting avoidance of smoking during pregnancy may help in lowering the disease burden, with Indigenous children likely to benefit most.

Respiratory Syncytial Virus Infection in High-risk Infants - an Update on Palivizumab Prophylaxis

Morbidity due to respiratory syncytial virus (RSV) disease is still high in infants and children worldwide during the first two to five years of life. Certain categories of high-risk infants with increased morbidity and mortality attributed to RSV disease have been identified and are included in national recommendations for prophylaxis with the monoclonal RSV antibody palivizumab. Most guidelines recommend palivizumab for preterm infants born less than or equal to 32 weeks gestational age with or without bronchopulmonary dysplasia, those born between 33 and 35 weeks gestational age with additional risk factors, and infants and children with hemodynamically significant congenital heart disease. Over the last years several rare diseases have been identified demonstrating high morbidity associated with RSV disease, thus, extension of guidelines for the prophylaxis with palivizumab for these patients with rare diseases including children with malignancy, congenital and acquired immune deficiency, Down syndrome, neuromuscular impairment, cystic fibrosis, congenital diaphragmatic hernia and other severe respiratory disease is increasingly discussed. Efficacy of palivizumab prophylaxis is documented by meta-analysis, and different economic analyses demonstrate cost-effectiveness of palivizumab for the most common indications during the first RSV season.

Respiratory syncytial virus infections in infants and children with congenital heart disease: update on the evidence of prevention with palivizumab

PURPOSE OF REVIEW

Lower respiratory tract infections multiply morbidity and mortality within patients with significant congenital heart disease (CHD). For respiratory syncytial virus (RSV), one of the most important pathogens, immunoprophylaxis with palivizumab has successfully been introduced. The question is which patients will benefit most from this costly preventive treatment.

RECENT FINDINGS

The era after the introduction of palivizumab has revealed a steep decrease in mortality. The markers of success - hospital stays, admission to the intensive care unit, days on mechanical ventilation, and death - consistently favor immunoprophylaxis. The key point of treatment success remains in all cases a careful patient selection, adherence to a time limit of 30 days between the injections and early use after cardiac surgery with cardiopulmonary bypass, as well as avoidance of nosocomial-acquired infections. Preventive therapy with palivizumab in patients with CHD has been investigated in terms of operating efficiency - with the lowest costs per quality-adjusted life years compared with preterm infants with or without bronchopulmonary dysplasia.

SUMMARY

The burden of RSV disease will decline, once a vaccine is available. Meanwhile, immunoprophylaxis with palivizumab is a useful tool for high-risk patients to reduce comorbidity and fatal outcome. Pharmacoeconomic considerations measuring quality-adjusted life years indicate important information about cost-effectiveness.

Cost-effectiveness of palivizumab for respiratory syncytial virus infection in high-risk children, based on long-term epidemiologic data from Austria

OBJECTIVE

To assess the cost-effectiveness of palivizumab, a monoclonal antibody against respiratory syncytial virus (RSV), in infants at high risk for severe RSV lower respiratory tract infection, such as premature infants, infants with bronchopulmonary dysplasia, and those with congenital heart disease, based on long-term epidemiologic data from Austria.

METHODS

A decision-tree model was used, and the analysis was based on a lifetime follow-up investigating cost-effectiveness of palivizumab versus no RSV infection prevention. The primary perspective of the study was that of the healthcare system, the second that of society. Cost and effects were discounted by 5%. The base case analysis included only direct medical costs, and a scenario analysis included various indirect costs.

RESULTS

Analyses were based on epidemiologic data on a total of 1579 children hospitalized because of RSV lower respiratory tract infection during 16 seasons. The incremental cost-effectiveness ratio for the first outcome measure (life years gained) amounted to discounted costs of €34,956 (for all preterm infants), €35,056 (for < 33 weeks' gestational age [wGA] infants), €35,233 (for 33-35 wGA infants), €35,611 (for infants with bronchopulmonary dysplasia), and €8956 (for infants with congenital heart disease). Use of palivizumab compared with no prophylaxis had an incremental cost-utility ratio of €26,212, €26,292, €24,392, €24,654, and €8484, respectively, per quality-adjusted life years. Results from the society perspective were more cost-effective in all study populations. An additional scenario analysis with 7 injections for the 33 to 35 wGA group revealed cost-effectiveness as well.

CONCLUSIONS

Our results based on nationwide long-term epidemiologic data suggest that palivizumab is cost-effective in prevention of RSV disease in high-risk infants.