RSV immune globulin prophylaxis: is an ounce of prevention worth a pound of cure?

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.

Respiratory syncytial virus infection and immunoprophylaxis for selected high-risk children in Central Australia

BACKGROUND

There are limited data on the epidemiology and viral aetiology of bronchiolitis in Central Australia and respiratory syncytial virus (RSV) immunoprophylaxis in an Australian population.

OBJECTIVE

To (i) determine the incidence and the viral aetiology of bronchiolitis hospitalisations and (ii) report on the usage of RSV immunoprophylaxis in selected high-risk infants and children in Central Australia.

METHODOLOGY

A retrospective review was performed of all hospital separations for bronchiolitis for a three-year period, 1998-2000. Respiratory viruses in the nasopharyngeal aspirates were identified from the cases in the year 2000. A combined retrospective chart review and prospective follow up study was undertaken of all the infants and children who received RSV immunoprophylaxis at the Alice Springs Hospital, Central Australia.

RESULTS

Incidence of bronchiolitis hospitalisation in infants for 1998, 1999 and 2000 were 176, 200 and 180 per 1000, respectively. Nine high-risk children had RSV immunoprophylaxis on a total of 46 occasions and there were two mild RSV-related illnesses in them. None had severe lower respiratory tract illness.

CONCLUSION

The incidence of bronchiolitis in Central Australia is extremely high. The usage of RSV immunoprophylaxis may be justified in selected high-risk children living in high endemic areas.

Palivizumab for preterm infants. Is it worth it?

Respiratory syncytial virus infection is an important cause of morbidity. Although palivizumab prophylaxis is widely used, it is uncertain whether the cost is justified. A systematic review was therefore performed of the safety, efficacy, and the likely cost effectiveness of prophylaxis for preterm infants in the United Kingdom using a standard search strategy. The only randomised controlled trial identified showed a reduction in hospital admission but no benefit on more serious outcomes. None of the United Kingdom cost studies showed economic benefit for palivizumab prophylaxis. New treatments are rarely cost effective, and, in the absence of a comprehensive economic assessment, continued use for high risk infants may appear justified.

Respiratory syncytial virus bronchiolitis in ex-preterm infants in the Scottish highlands: review of hospital admissions and an analysis of hospital cost

Ex-preterm infants are vulnerable to respiratory syncytial virus (RSV) bronchiolitis and their hospital admission is associated with increased morbidity. Palivizumab is currently available as prophylaxis against RSV infection but its use in ex-preterm infants is controversial. A retrospective case review study was, therefore, carried out to determine the rate of readmission with RSV bronchiolitis among ex-preterm infants in the Highland Region of Scotland and to estimate the hospital cost per admission. Between 1995 and 1999, a total of 3,046 children under 2 years of age were admitted to Raigmore Hospital, 1,691 of whom (60.4%) lived outwith Inverness. 507 children had acute bronchiolitis and ex preterm infants with RSV positive bronchiolitis accounted for 3.6% of total admissions with acute bronchiolitis. 72% of these children lived outwith Inverness. The median length of hospital stay for children born at less than 30 weeks and for children who had had bronchopulmonary dysplasia (BPD) was 6 and 10.5 days respectively. The average hospital costs per admission for children of less than 30 weeks and children of more than 30 weeks were 3,376 Pounds and 2,074 Pounds respectively. It was more expensive for children with BPD (4,431 Pounds per admission) when compared with those without BPD (1,959 Pounds per admission). This study has shown that most of the children admitted to hospital lived outwith Inverness, many at some considerable distance, and this, as much as severity of illness, may have contributed to hospital admission. Further studies are required to determine productivity losses associated with RSV infection and justification of use of Palivizumab in ex preterm infants of less than 30 weeks gestation and of BPD living in remote areas of Scottish Highlands.

The clinical and health economic burden of respiratory syncytial virus disease among children under 2 years of age in a defined geographical area

AIMS

To describe the clinical and health economic impact of respiratory syncytial virus (RSV) disease in children under 2 years of age.

METHODS

Hospitalised children less than 2 years of age with a respiratory illness were studied over three consecutive RSV seasons (1996-99).

RESULTS

The rates (per 1000 infants under 1 year of age) of hospitalisations from bronchiolitis and RSV illness were 30.8 and 24.4 respectively. The rates of death, intensive care admission, and need for ventilatory assistance during RSV related hospitalisation were 0.2%, 2.7%, and 1.5% respectively. From a cohort of 841 preterm infants, 6.3% had an RSV related hospitalisation during the study period, with the rate rising to 9.2% among those who were either born before 36 weeks gestation and were under 6 months of age at the onset of the RSV seasons, or were less than 2 years of age with chronic lung disease needing home oxygen therapy. Eight of 25 children on home oxygen therapy had RSV related rehospitalisation. Need for assisted ventilation during the neonatal period and discharge home on oxygen therapy were significantly associated with the risk of subsequent RSV related hospitalisation in preterm infants less than 6 months of age. The direct health authority cost of all RSV hospitalisations was pound 542 203, while the currently recommended immunoprophylaxis for the high risk infants would have cost pound 652 960.

CONCLUSIONS

Preterm infants receiving assisted ventilation and those on home oxygen therapy are particularly at risk of RSV related hospitalisation. Serious adverse outcomes are however uncommon even among these high risk infants.

Palivizumab prophylaxis of respiratory syncytial virus infection in high-risk infants

Palivizumab prophylaxis significantly reduces hospitalization for respiratory syncytial virus (RSV) disease in preterm infants. However, palivizumab is very expensive. Data from a New Zealand cost-effectiveness analysis were considered by representatives of the Infectious Diseases and Immunisation, Fetus and Newborn, and Respiratory Committees of the Paediatric Society of New Zealand. Prophylaxis in all high-risk groups was associated with net cost. The consensus panel recommends that the priority for palivizumab be given to babies discharged on home oxygen with chronic lung disease, followed by babies born at 28 weeks or less gestation.

Cost-effectiveness of palivizumab in New Zealand

OBJECTIVE

To establish the preterm infant hospitalization risks from respiratory syncytial virus (RSV) in New Zealand and the net cost per hospitalization averted by palivizumab.

METHODS

The 437 infants born < 32 weeks' gestation in 1997 and treated at five major neonatal units were identified. Subsequent admissions during the next 2 years for bronchiolitis, pneumonia and croup were tracked, and information collected on RSV tests performed. Data on the length of stay and hospital costs were used to calculate the potential net cost per hospitalization averted associated with the use of palivizumab and the number needed to treat (NNT) to prevent one hospitalization.

RESULTS

Estimated RSV readmission risk before 1 year corrected age in infants < 32 weeks' gestation discharged home on oxygen, and those " 28 weeks' gestation, or between 29 and 31 weeks' gestation with or without chronic lung disease was 42%, 23%, 19%, 10% and 8%, respectively. The NNT with palivizumab to prevent one hospitalization ranged from six to 26 across subgroups. Mean (range) net cost per hospitalization averted was 60,000 New Zealand dollars ($28,000-$166,700). In no subgroup would prophylaxis result in net cost saving. Prophylaxis for all NZ infants " 28 weeks' gestation would cost approximately $1,090,000 net and prevent 29 hospitalizations annually, being equivalent to $37,000 net per hospitalization averted, with eight infants treated to prevent one hospitalization. Alternative assumptions about cost and efficacy failed to alter these findings.

CONCLUSION

If value is placed on preventing morbidity, the priority groups for palivizumab prophylaxis are preterm infants discharged home on oxygen, followed by preterm infants of 28 weeks' gestation or less.

Antibodies for the prevention and treatment of viral diseases

This paper reviews current use and evolving role of polyclonal and monoclonal antibody products for the prevention and treatment of viral diseases. Antibodies continue to be indicated for prophylaxis either prior to an anticipated exposure especially in situations of travel, or more commonly following an exposure. The predominant indication for use of antibody products is to prevent infection. With the availability of vaccines for the prevention of chickenpox, hepatitis A, hepatitis B, measles, rabies and smallpox, the role of passive immunization is reserved for susceptible individuals and those at high risk for complications of infection. Risks of transmission of infections associated with use of human plasma-derived products have been reduced by improvements in donor screening and virus removal and inactivation procedures. An additional safety concern has been addressed by the removal of thimerosal as a preservative. Within the last 5 years, two antibodies have been licensed for a viral indication, RespiGam and Synagis both for prevention of respiratory syncytial virus infection. RespiGam is a human plasma derived antibody and Synagis is a humanized monoclonal antibody, the first such antibody to be licensed for an infectious disease indication. CytoGam for prevention of cytomegalovirus infection in kidney transplant patients has recently been granted an expanded indication to include use in lung, liver, pancreas and heart transplant patients. As the use of therapeutics becomes more sophisticated, researchers may find better ways of using antibody products.

Hospitalisation for RSV infection in ex-preterm infants-implications for use of RSV immune globulin

BACKGROUND

Respiratory syncytial virus (RSV) specific immune globulin is now being marketed for prevention of RSV infection in ex-preterm infants. However, there are no published UK data on the morbidity or mortality from RSV in these infants.

AIMS

To determine the morbidity and mortality from RSV infection in a cohort of infants previously treated at a regional neonatal unit, and compare the cost of hospitalisation for RSV with the potential cost of administering RSV immune globulin (RSV-IG) prophylaxis.

METHODS

Infants born at a gestation of less than 32 weeks were studied. Details of admissions for respiratory illness in the first two years of life were collected from hospital records, referring hospitals, and general practitioners.

RESULTS

Data on 82 infants were collected. Up to three RSV seasons were encountered. The hospitalisation rate for confirmed RSV infection for the first season encountered was 4%. Rates of ward and paediatric intensive care unit admission were higher for infants with chronic lung disease. There were no deaths from RSV. RSV-IG would not have been cost effective for most infants.

CONCLUSION

The morbidity and mortality rates from RSV observed in this group do not support the widespread introduction of RSV-IG prophylaxis for ex-preterm infants.