Morbidity and mortality after RSV-associated hospitalizations among premature Canadian infants

Cost-effectiveness of nirsevimab and palivizumab for respiratory syncytial virus prophylaxis in preterm infants 29-34 6/7 weeks' gestation in the United States

BACKGROUND

Respiratory syncytial virus (RSV) hospitalizations have increased since the 2014 guideline update recommended against the use of palivizumab for preterm infants born ≥29 0/7 weeks' gestational age (GA) without additional risk factors. A novel drug candidate, nirsevimab, has been developed for this population. We analyzed the cost-effectiveness of palivizumab/nirsevimab vs. no prophylaxis in this population.

METHODS

A hybrid-Markov model predicted the RSV clinical course in the first year of life and sequelae in the subsequent four years for preterm infants from the healthcare and societal perspectives. Model parameters were derived from the literature. We calculated costs and quality-adjusted life-years (QALYs) to produce an incremental cost-effectiveness ratio (ICER) evaluated at a willingness-to-pay threshold of $150,000/QALY. Sensitivity analyses assessed model robustness. A threshold analysis examined nirsevimab pricing uncertainty.

RESULTS

Compared to no prophylaxis, palivizumab costs $9572 and $9584 more from the healthcare and societal perspectives, respectively, with 0.0019 QALYs gained per patient over five years, resulting in ICERs >$5 million per QALY from each perspective. Results were robust to parameter uncertainties; probabilistic sensitivity analysis revealed that no prophylaxis had a 100% probability of being cost-effective. The threshold analysis suggested that nirsevimab is not cost-effective when compared to no prophylaxis if the price exceeds $1962 from a societal perspective.

CONCLUSION

Palivizumab is dominated by no prophylaxis for preterm infants 29 0/7-34 6/7 weeks' GA with no additional risk factors. Relevant stakeholders should consider alternatives to palivizumab for this population that are both effective and economical.

Cost-effectiveness analysis of nirsevimab and maternal RSVpreF vaccine strategies for prevention of Respiratory Syncytial Virus disease among infants in Canada: a simulation study

Background

The cost-effectiveness of immunisation strategies with a long-acting monoclonal antibody (nirsevimab) and/or a protein-based maternal vaccine (RSVpreF) for protecting infants from Respiratory Syncytial Virus (RSV)-associated illness has not been previously determined for Canada. We estimated the health benefits and cost-effectiveness of nirsevimab for immunising the entire birth cohort, regardless of gestational age or other risk factors. Additionally, we evaluated the health benefits and cost-effectiveness of a combined strategy of year-round vaccination of pregnant women with RSVpreF and immunisation of infants at high risk, including those born preterm or with chronic conditions, with nirsevimab during the RSV season.

Methods

We developed a discrete-event simulation model, parameterized with the data on medically-attended RSV infections among infants under one year of age from 2010 to 2019, including outpatient care, hospitalisations, and deaths. Intervention scenarios targeting twelve monthly birth cohorts and pregnant women, reflecting the 2021 census data for Ontario, Canada were evaluated over a follow-up time horizon of one year from birth. Taking into account the costs (in 2023 Canadian dollars) associated with RSV-related outcomes, we calculated the net monetary benefit using the quality-adjusted life-year (QALY) gained. Further, we determined the range of price-per-dose (PPD) for nirsevimab and RSVpreF within which the program was cost-effective. Cost-effectiveness analyses were conducted from both healthcare and societal perspectives.

Findings

Using a willingness-to-pay of CAD$50,000 per QALY gained, we found that immunising the entire birth cohort with nirsevimab would be cost-effective from a societal perspective for a PPD of up to $290, with an annual budget impact of $83,978 for 1113 infants per 100,000 population. An alternative, combined strategy of vaccinating pregnant women and immunising only infants at high risk of severe disease would lead to a lower budget impact of $49,473 per 100,000 population with a PPD of $290 and $195 for nirsevimab and RSVpreF vaccine, respectively. This combined strategy would reduce infant mortality by 76%-85%, comparable to a 78% reduction achieved through a nirsevimab-only program of the entire birth cohort. The PPD for cost-effective programs with nirsevimab was sensitive to the target population among infants.

Interpretation

Passive immunisation of infants under 6 months of age with nirsevimab and vaccination of pregnant women with RSVpreF could be a cost-effective strategy for protecting infants during their first RSV season.

Funding

This study was supported by the Canadian Immunisation Research Network (CIRN) and the Canadian Institutes of Health Research (CIHR). Seyed M. Moghadas acknowledges support from the Natural Sciences and Engineering Research Council of Canada (MfPH and Discovery grants). Alison P. Galvani acknowledges support from the The Notsew Orm Sands Foundation.

New insights into the natural history of bronchopulmonary dysplasia from proteomics and multiplexed immunohistochemistry

Bronchopulmonary dysplasia (BPD) is a disease of prematurity related to the arrest of normal lung development. The objective of this study was to better understand how proteome modulation and cell-type shifts are noted in BPD pathology. Pediatric human donors aged 1-3 yr were classified based on history of prematurity and histopathology consistent with "healed" BPD (hBPD, n = 3) and "established" BPD (eBPD, n = 3) compared with respective full-term born (n = 6) age-matched term controls. Proteins were quantified by tandem mass spectroscopy with selected Western blot validations. Multiplexed immunofluorescence (MxIF) microscopy was performed on lung sections to enumerate cell types. Protein abundances and MxIF cell frequencies were compared among groups using ANOVA. Cell type and ontology enrichment were performed using an in-house tool and/or EnrichR. Proteomics detected 5,746 unique proteins, 186 upregulated and 534 downregulated, in eBPD versus control with fewer proteins differentially abundant in hBPD as compared with age-matched term controls. Cell-type enrichment suggested a loss of alveolar type I, alveolar type II, endothelial/capillary, and lymphatics, and an increase in smooth muscle and fibroblasts consistent with MxIF. Histochemistry and Western analysis also supported predictions of upregulated ferroptosis in eBPD versus control. Finally, several extracellular matrix components mapping to angiogenesis signaling pathways were altered in eBPD. Despite clear parsing by protein abundance, comparative MxIF analysis confirms phenotypic variability in BPD. This work provides the first demonstration of tandem mass spectrometry and multiplexed molecular analysis of human lung tissue for critical elucidation of BPD trajectory-defining factors into early childhood.NEW & NOTEWORTHY We provide new insights into the natural history of bronchopulmonary dysplasia in donor human lungs after the neonatal intensive care unit hospitalization. This study provides new insights into how the proteome and histopathology of BPD changes in early childhood, uncovering novel pathways for future study.

Impact of using the International Risk Scoring Tool on the cost-utility of palivizumab for preventing severe respiratory syncytial virus infection in Canadian moderate-to-late preterm infants

BACKGROUND AND OBJECTIVE

To assess the cost-utility of palivizumab versus no prophylaxis in preventing severe respiratory syncytial virus (RSV) infection in Canadian moderate-to-late preterm (32-35 weeks' gestational age) infants using an: i) International Risk Scoring Tool (IRST); ii) Canadian RST (CRST).

METHODS

A decision tree was developed to assess cost-utility. Infants assessed at moderate- and high-risk of RSV-related hospitalization (RSVH) by the IRST or CRST received palivizumab or no prophylaxis and then progressed to either: i) RSVH; ii) emergency room/outpatient medically attended RSV-infection (MARI); or, iii) were uninfected/non-medically attended. Infants admitted to intensive care could incur mortality (0.43%). Respiratory morbidity was accounted in all uninfected surviving infants for 6 years or 18 years (RSVH/MARI). Palivizumab efficacy (72.2% RSVH reduction) and hospital outcomes were from the Canadian CARESS, PICNIC and RSV-Quebec studies. Palivizumab costs (50mg: CAN$752; 100mg: $1,505) were calculated from Canadian birth statistics combined with a growth algorithm. Healthcare/payer and societal costs (May 2022; 1.5% discounting) were included.

RESULTS

Cost per quality-adjusted life year (QALY) was $29,789 with the IRST (0.79 probability of being <$50,000) and $15,833 with the CRST (0.96 probability). The model was most sensitive to utility scores, long-term sequelae, and palivizumab cost. Vial sharing improved the incremental cost-utility ratio (IRST: $22,319; CRST: $9,231).

CONCLUSIONS

Palivizumab was highly cost-effective (vs no prophylaxis) in Canadian moderate-to-late preterm infants using either the IRST or CRST. The IRST has fewer risk factors than the CRST (3 vs 7, respectively), captures more potential RSVHs (85% vs 54%) and provides another option to guide cost-effective RSV prophylaxis in Canada.

Low Dose Hyperoxia Primes Airways for Fibrosis in Mice after Influenza A Infection

It is well known that supplemental oxygen used to treat preterm infants in respiratory distress is associated with permanently disrupting lung development and the host response to influenza A virus (IAV). However, many infants who go home with normally functioning lungs are also at risk for hyperreactivity after a respiratory viral infection. We recently reported a new, low-dose hyperoxia mouse model (40% for 8 days; 40x8) that causes a transient change in lung function that resolves, rendering 40x8 adult animals functionally indistinguishable from room air controls. Here we reported that when infected with IAV, 40x8 mice display an early transient activation of TGFβ signaling and later airway hyperreactivity associated with peribronchial inflammation (profibrotic macrophages) and fibrosis compared to infected room air controls, suggesting neonatal oxygen induced hidden molecular changes that prime the lung for hyperreactive airways disease. While searching for potential activators of TGFβ signaling, we discovered that thrombospondin-1 (TSP-1) is elevated in naïve 40x8 mice compared to controls and localized to lung megakaryocytes and platelets before and during IAV infection. Elevated TSP-1 was also identified in human autopsy samples of former preterm infants with bronchopulmonary dysplasia. These findings reveal how low doses of oxygen that do not durably change lung function may prime it for hyperreactive airways disease by changing expression of genes, such as TSP-1, thus helping to explain why former preterm infants who have normal lung function are susceptible to airway obstruction and increased morbidity after viral infection.

Challenges in the prevention or treatment of RSV with emerging new agents in children from low- and middle-income countries

INTRODUCTION

Respiratory syncytial virus (RSV) causes approximately 120,000 deaths annually in children <5 years, with 99% of fatalities occurring in low- and middle-income countries (LMICs).

AREAS COVERED

There are numerous RSV interventions in development, including long-acting monoclonal antibodies, vaccines (maternal and child) and treatments which are expected to become available soon. We reviewed the key challenges and issues that need to be addressed to maximize the impact of these interventions in LMICs. The epidemiology of RSV in LMICs was reviewed (PubMed search to 30 June 2020 inclusive) and the need for more and better-quality data, encompassing hospital admissions, community contacts, and longer-term respiratory morbidity, emphasized. The requirement for an agreed clinical definition of RSV lower respiratory tract infection was proposed. The pros and cons of the new RSV interventions are reviewed from the perspective of LMICs.

EXPERT OPINION

We believe that a vaccine (or combination of vaccines, if practicable) is the only viable solution to the burden of RSV in LMICs. A coordinated program, analogous to that with polio, involving governments, non-governmental organizations, the World Health Organization, the manufacturers and the healthcare community is required to realize the full potential of vaccine(s) and end the devastation of RSV in LMICs.

Respiratory Syncytial Virus Prophylaxis in Infants With Congenital Diaphragmatic Hernia in the Canadian Respiratory Syncytial Virus Evaluation Study of Palivizumab, 2005-2017

BACKGROUND

Infants with congenital diaphragmatic hernia (CDH) are at an increased risk of respiratory morbidity from recurrent respiratory tract infections including those from respiratory syncytial virus (RSV). Prospective studies on RSV prophylaxis in CDH infants are limited. We determined the risk of respiratory illness- and RSV-related hospitalizations (RIH and RSVH, respectively) among infants prophylaxed for CDH, standard indications (SIs) and those without increased risk (NR).

METHODS

The prospective Canadian Respiratory Syncytial Virus Evaluation Study of Palivizumab (CARESS) registry was searched for infants who received palivizumab during 12 RSV seasons (2005-2017) in Canada. Cox proportional hazards analyses were conducted to compare RIH and RSVH risks across the groups adjusted for potential confounders.

RESULTS

In total, 21 107 infants (201 CDH, 389 NR, and 20 517 SI) were included. RIH incidences were 10.0% (CDH), 2.1% (NR), and 6.2% (SI). CDH patients had a significantly higher RIH hazard compared with NR (hazard ratio [HR], 3.6 [95% confidence interval {CI}, 1.5-8.8]; P = .005) but not SI (HR, 1.2 [95% CI, .8-2.0]; P = .379). RSVH incidences were 0.6%, 0.3%, and 1.5% for CDH, NR, and SI, respectively. RSVH risk was similar across groups (SI: HR, 0.0, P = .922; NR: HR, 0.0, P = .934).

CONCLUSIONS

CDH infants had a 3-fold increased risk of RIH compared to NR but not SI infants. RSVH risk was similar with low RSVH incidences across all groups, implying that CDH infants may benefit from palivizumab during the RSV season, similar to other high-risk groups.

CLINICAL TRIALS REGISTRATION

NCT00420966.

Burden of respiratory syncytial virus hospitalisation among infants born at 32-35 weeks' gestational age in the Northern Hemisphere: pooled analysis of seven studies

To provide comprehensive information on the epidemiology and burden of respiratory syncytial virus hospitalisation (RSVH) in preterm infants, a pooled analysis was undertaken of seven multicentre, prospective, observational studies from across the Northern Hemisphere (2000–2014). Data from all 32⁰–35⁶ weeks' gestational age (wGA) infants without comorbidity were analysed. RSVH occurred in 534/14 504 (3.7%) infants; equating to a rate of 5.65 per 100 patient-seasons, with the rate in individual wGA groups dependent upon exposure time (P = 0.032). Most RSVHs (60.1%) occurred in December–January. Median age at RSVH was 88 days (interquartile range (IQR): 54–159). Respiratory support was required by 82.0% of infants: oxygen in 70.4% (median 4 (IQR: 2–6) days); non-invasive ventilation in 19.3% (median 3 (IQR: 2–5) days); and mechanical ventilation in 10.2% (median 5 (IQR: 3–7) days). Intensive care unit admission was required by 17.9% of infants (median 6 days (IQR: 2–8) days). Median overall hospital length of stay (LOS) was 5 (IQR: 3–8) days. Hospital resource use was similar across wGA groups except for overall LOS, which was shortest in those born 35 wGA (median 3 vs. 4–6 days for 32–34 wGA; P < 0.001). Strategies to reduce the burden of RSVH in otherwise healthy 32–35 wGA infants are indicated.

The impact of respiratory viruses on lung health after preterm birth

Children born preterm, less than 37 weeks' gestation, are at increased risk of viral respiratory infections and associated complications both during their initial birth hospitalisation and in their first years following discharge. This increased burden of viral respiratory infections is likely to have long term implications for lung health and function in individuals born preterm, particularly those with bronchopulmonary dysplasia. Several hypotheses have been put forward to explain the association between early life viral respiratory infection and development of suboptimal lung health and function later in life following preterm birth. Although preterm infants with diminished lung function, particularly small airways, might be particularly susceptible to asthma and wheezing disorders following viral infection, there is evidence that respiratory viruses can activate number of inflammatory and airway re-modelling pathways. Therefore, the aim of this review is to highlight the perinatal and early life risk factors that may contribute to increased susceptibility to viral respiratory infections among preterm infants during early life and to understand how respiratory viral infection may influence the development of abnormal lung health and function later in life.

Cost-effectiveness of rule-based immunoprophylaxis against respiratory syncytial virus infections in preterm infants

The objective of the paper is to assess the cost-effectiveness of targeted respiratory syncytial virus (RSV) prophylaxis based on a validated prediction rule with 1-year time horizon in moderately preterm infants compared to no prophylaxis. Data on health care consumption were derived from a randomised clinical trial on wheeze reduction following RSV prophylaxis and a large birth cohort study on risk prediction of RSV hospitalisation. We calculated the incremental cost-effectiveness ratio (ICER) of targeted RSV prophylaxis vs. no prophylaxis per quality-adjusted life year (QALYs) using a societal perspective, including medical and parental costs and effects. Costs and health outcomes were modelled in a decision tree analysis with sensitivity analyses. Targeted RSV prophylaxis in infants with a first-year RSV hospitalisation risk of > 10% resulted in a QALY gain of 0.02 (0.931 vs. 0.929) per patient against additional cost of €472 compared to no prophylaxis (ICER €214,748/QALY). The ICER falls below a threshold of €80,000 per QALY when RSV prophylaxis cost would be lowered from €928 (baseline) to €406 per unit. At a unit cost of €97, RSV prophylaxis would be cost saving.

CONCLUSIONS

Targeted RSV prophylaxis is not cost-effective in reducing RSV burden of disease in moderately preterm infants, but it can become cost-effective if lower priced biosimilar palivizumab or a vaccine would be available.

Cost-utility analysis of Palivizumab for Respiratory Syncytial Virus infection prophylaxis in preterm infants: update based on the clinical evidence in Spain

Background

This study aimed at estimating the efficiency of palivizumab in the prevention of Respiratory Syncytial Virus (RSV) infection and its sequelae in preterm infants (32^{day 1}-35^{day 0}weeks of gestational age –wGA-) in Spain.

Methods

A decision-tree model was developed to compare health benefits (Quality Adjusted Life Years-QALYs) and costs of palivizumab versus a non-prophylaxis strategy over 6 years. A hypothetical cohort of 1,000 preterm infants, 32^{day 1}-35^{day 0} wGA (4.356 kg average weight) at the beginning of the prophylaxis (15 mg/kg of palivizumab; 3.88 average number of injections per RSV season) was analysed.

The model considered the most recent evidence from Spanish observational and epidemiological studies on RSV infection: the FLIP II study provided hospital admission and Intensive Care Unit (ICU) admission rates; in-hospital mortality rate was drawn from an epidemiological study from 2004 to 2012; recurrent wheezing rates associated to RSV infection from SPRING study were adjusted by the evidence on the palivizumab effect from clinical trials. Quality of life baseline value, number of hospitalized infants and the presence of recurrent wheezing over time were granted to estimate QALYs.

National Health Service and societal perspective (included also recurrent wheezing indirect cost) were analysed. Total costs (€, 2016) included pharmaceutical and administration costs, hospitalization costs and recurrent wheezing management annual costs. A discount rate of 3.0% was applied annually for both costs and health outcomes.

Results

Over 6 years, the base case analysis showed that palivizumab was associated to an increase of 0.0731 QALYs compared to non-prophylaxis. Total costs were estimated in €2,110.71 (palivizumab) and €671.68 (non-prophylaxis) from the National Health System (NHS) perspective, resulting in an incremental cost utility ratio (ICUR) of €19,697.69/QALYs gained (prophylaxis vs non-prophylaxis). Results derived from the risk-factors population subgroups analysed were in line with the total population results. From the societal perspective, the incremental cost associated to palivizumab decreased to an €1,253.14 (ICUR = €17,153.16€/QALYs gained for palivizumab vs non-prophylaxis). One-way and probabilistic sensitivity analyses confirmed the robustness of the model.

Conclusions

The prophylaxis with palivizumab is efficient for preventing from RSV infections in preterm infants 32^{day 1}-35^{day 0} wGA in Spain.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2803-0) contains supplementary material, which is available to authorized users.

Defining the Risk and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Preterm Infants Without Chronic Lung Disease or Congenital Heart Disease

INTRODUCTION

The REGAL (RSV Evidence-a Geographical Archive of the Literature) series provide a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This second publication covers the risk and burden of RSV infection in preterm infants born at <37 weeks' gestational age (wGA) without chronic lung disease or congenital heart disease.

METHODS

A systematic review was undertaken for articles published between January 1, 1995 and December 31, 2015. Studies reporting data for hospital visits/admissions for RSV infection among preterm infants as well as studies reporting RSV-associated morbidity, mortality, and risk factors were included. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULTS

2469 studies were identified of which 85 were included. Preterm infants, particularly those born at lower wGA, tended to have higher RSV hospitalization (RSVH) rates compared with otherwise healthy term infants (high SOE). RSVH rates ranged from ~5 per 1000 children to >100 per 1000 children with the highest rates shown in the lowest gestational age infants (high SOE). Independent risk factors associated with RSVH include: proximity of birth to the RSV season, living with school-age siblings, smoking of mother during pregnancy or infant exposure to environmental smoking, reduced breast feeding, male sex, and familial atopy (asthma) (high SOE). Predictive models can identify 32/33-35 wGA infants at risk of RSVH (high SOE).

CONCLUSION

RSV infection remains a major burden on Western healthcare systems and is associated with significant morbidity. Further studies focusing on the prevalence and burden of RSV in different gestational age cohorts, the changing risk of RSVH during the first year of life, and on RSV-related mortality in preterm infants are needed to determine the true burden of disease.

FUNDING

AbbVie.

Respiratory Syncytial Virus Hospitalizations in Healthy Preterm Infants: Systematic Review

BACKGROUND

Studies have explored the risk for and impact of respiratory syncytial virus (RSV) infection requiring hospitalization among healthy preterm infants born at 29-35 weeks of gestational age not given RSV immunoprophylaxis. We performed a systematic review and qualitative synthesis of these studies.

METHODS

Two experienced reviewers used prespecified inclusion/exclusion criteria to screen titles/abstracts and full-text studies using MEDLINE, Embase, BIOSIS and Cochrane Library (January 1, 1985, to November 6, 2014). We abstracted data on risk factors for RSV hospitalization, incidence and short- and long-term outcomes of RSV hospitalization. Using standard procedures, we assessed study risk of bias and graded strength of evidence (SOE).

RESULTS

We identified 4754 records and reviewed 27. Important risk factors for RSV hospitalization included young age during the RSV season, having school-age siblings and day-care attendance, with odds ratios >2.5 in at least one study (high SOE). Incidence rates for RSV hospitalizations ranged from 2.3% to 10% (low SOE). Length of hospital stays ranged from 3.8 to 6.1 days (low SOE). Recurrent wheezing rates ranged from 20.7% to 42.8% 1 to 2 years after RSV hospitalization (low SOE).

CONCLUSIONS

Young chronological age and some environmental risk factors are important clinical indicators of an increased risk of RSV hospitalization in healthy preterm infants 32 to 35 weeks of gestational age. SOE was low for estimates of incidence of RSV hospitalizations, in-hospital resource use and recurrent wheezing in this population. Studies were inconsistent in study characteristics, including weeks of gestational age, age during RSV season and control for confounding factors.

The influence of birth weight amongst 33-35 weeks gestational age (wGA) infants on the risk of respiratory syncytial virus (RSV) hospitalisation: a pooled analysis

OBJECTIVE

To investigate the association between birth weight and respiratory syncytial virus (RSV) hospitalisation during the first year of life in 33°-35⁶ weeks' gestational age (wGA) infants.

STUDY DESIGN

Pooled analysis of data (n = 1218) from Spain, Germany, France and Italy.

RESULT

RSV hospitalised infants overall had a significantly higher birth weight than non-hospitalised infants (2.24 versus 2.14 kg; p < 0.001) for both males (2.25 versus 2.18 kg; p = 0.049) and females (2.22 versus 2.11 kg, p = 0.007). The effect was significant only in 34 wGA infants (33 wGA: hospitalised 1.95 kg versus non-hospitalised 1.95 kg, p = 0.976; 34 wGA: 2.26 versus 2.14 kg, p = 0.007; 35 wGA: 2.37 versus 2.29 kg, p = 0.070), particularly female 34 wGA infants (female: 2.24 versus 2.08 kg, p = 0.019; male: 2.27 versus 2.20, p = 0.191). Birth weight was shown to be an independent risk factor for RSV hospitalisation.

CONCLUSIONS

In 33-35 wGA infants, a higher birth weight appeared independently associated with an increased risk of RSV hospitalisation.

Risk of respiratory syncytial virus infection in preterm infants: reviewing the need for prevention

Premature infants are at substantial risk for a spectrum of morbidities that are gestational age dependent. Respiratory syncytial virus (RSV) infection is most common in the first two years of life with the highest burden in children aged <6 months. Preterm infants ≤35 weeks' gestation are handicapped by incomplete immunological and pulmonary maturation and immature premorbid lung function with the added risk of bronchopulmonary dysplasia. Superimposed RSV infection incites marked neutrophilic airway inflammation and innate immunological responses that further compromise normal airway modeling. This review addresses the epidemiology and burden of RSV disease, focusing on the preterm population. Risk factors that determine RSV-disease severity and hospitalization and the impact on healthcare resource utilization and potential long-term respiratory sequelae are discussed. The importance of disease prevention and the evidence-based rationale for prophylaxis with palivizumab is explored, while awaiting the development of a universal vaccine.

Serious Adverse Events in the Canadian Registry of Children Receiving Palivizumab (CARESS) for Respiratory Syncytial Virus Prevention

OBJECTIVES

To evaluate the safety and tolerability of palivizumab for RSV prophylaxis in high-risk children in everyday practice.

METHODS

High-risk children prophylaxed against RSV infection were recruited into a prospective, observational, Canadian RSV Evaluation Study of Palivizumab (CARESS) registry with active, serious adverse event (SAE) monitoring from 2008 to 2013. SAE reports were systematically collected and assessed for severity and relationship to palivizumab. Data were analyzed by Chi-square or Fisher Exact Tests to examine group differences in proportions.

RESULTS

13025 infants received 57392 injections. Hospitalizations for respiratory-related illness (RIH) were reported in 915 patients, and SAEs other than RIH were reported in 52 patients. Of these, 6 (0.05%) patients had a total of 14 hypersensitivity reactions that were deemed possibly or probably related to palivizumab (incidence: 2.8 per 10,000 patient-months). The SAEs of 42 patients were assessed as not related to palivizumab. SAEs in the remaining 4 patients were not classifiable as their records were incomplete. There were no significant demographic predictors of SAE occurrence.

CONCLUSIONS

Under active surveillance, a small proportion of infants in the CARESS registry experienced SAEs that had a potential relationship with palivizumab and these appeared to be unpredictable in terms of onset. Palivizumab appears to be a safe and well-tolerated antibody for RSV prophylaxis in high-risk children in routine practice.

Effectiveness of Palivizumab in Preventing RSV Hospitalization in High Risk Children: A Real-World Perspective

Infection with respiratory syncytial virus (RSV) is one of the major causes globally of childhood respiratory morbidity and hospitalization. Palivizumab, a humanized monoclonal antibody, has been recommended for high risk infants to prevent severe RSV-associated respiratory illness. This recommendation is based on evidence of efficacy when used under clinical trial conditions. However the real-world effectiveness of palivizumab outside of clinical trials among different patient populations is not well established. We performed a systematic review focusing on postlicensure observational studies of the protective effect of palivizumab prophylaxis for reducing RSV-associated hospitalizations in infants and children at high risk of severe infection. We searched studies published in English between 1 January 1999 and August 2013 and identified 420 articles, of which 20 met the inclusion criteria. This review supports the recommended use of palivizumab for reducing RSV-associated hospitalization rates in premature infants born at gestational age < 33 weeks and in children with chronic lung and heart diseases. Data are limited to allow commenting on the protective effect of palivizumab among other high risk children, including those with Down syndrome, cystic fibrosis, and haematological malignancy, indicating further research is warranted in these groups.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

Bronchiolitis is the most common cause of illness leading to hospitalization in young children. At present, many bronchiolitis management decisions are made subjectively, leading to significant practice variation among hospitals and physicians caring for children with bronchiolitis. To standardize care for bronchiolitis, researchers have proposed various models to predict the disease course to help determine a proper management plan. This paper reviews the existing state of the art of predictive modeling for bronchiolitis. Predictive modeling for respiratory syncytial virus (RSV) infection is covered whenever appropriate, as RSV accounts for about 70% of bronchiolitis cases.

METHODS

A systematic review was conducted through a PubMed search up to April 25, 2014. The literature on predictive modeling for bronchiolitis was retrieved using a comprehensive search query, which was developed through an iterative process. Search results were limited to human subjects, the English language, and children (birth to 18 years).

RESULTS

The literature search returned 2312 references in total. After manual review, 168 of these references were determined to be relevant and are discussed in this paper. We identify several limitations and open problems in predictive modeling for bronchiolitis, and provide some preliminary thoughts on how to address them, with the hope to stimulate future research in this domain.

CONCLUSIONS

Many problems remain open in predictive modeling for bronchiolitis. Future studies will need to address them to achieve optimal predictive models.

Genetic predisposition of RSV infection-related respiratory morbidity in preterm infants

The aim of this study was to assess whether prematurely born infants have a genetic predisposition to respiratory syncytial virus (RSV) infection-related respiratory morbidity. One hundred and forty-six infants born at less than 36 weeks of gestation were prospectively followed. Nasopharygeal aspirates were obtained on every occasion the infants had a lower respiratory tract infection (LRTI) regardless of need for admission. DNA was tested for 11 single-nucleotide polymorphisms (SNPs). Chronic respiratory morbidity was assessed using respiratory health-related questionnaires, parent-completed diary cards at a corrected age of 1 year and review of hospital notes. Lung function was measured at a post menstrual age (PMA) of 36 weeks and corrected age of 1 year. A SNP in ADAM33 was associated with an increased risk of developing RSV LRTIs, but not with significant differences in 36-week PMA lung function results. SNPs in several genes were associated with increased chronic respiratory morbidity (interleukin 10 (IL10), nitric oxide synthase 2A (NOS2A), surfactant protein C (SFTPC), matrix metalloproteinase 16 (MMP16) and vitamin D receptor (VDR)) and reduced lung function at 1 year (MMP16, NOS2A, SFTPC and VDR) in infants who had had RSV LRTIs.

CONCLUSIONS

Our results suggest that prematurely born infants may have a genetic predisposition to RSV LRTIs and subsequent respiratory morbidity which is independent of premorbid lung function.

Respiratory syncytial virus bronchiolitis in children

Respiratory syncytial virus is a highly infectious virus that commonly causes bronchiolitis and leads to high morbidity and a low, but important, incidence of mortality. Supportive therapy is the foundation of management. Hydration/nutrition and respiratory support are important evidence-based interventions. For children with severe disease, continuous positive airway pressure or mechanical ventilation may be necessary. Ribavirin may be used for treatment of patients with severe disease. Palivizumab provides important ongoing immunoprophylaxis during epidemic months for high-risk infants. Caregiver education and incorporating an explanation of all therapies and anticipatory guidance, including strategies for reducing the risk of infection, are vital.

Identifying and ensuring optimal care for all children at risk of developing serious respiratory syncytial virus disease: a Canadian nurses' perspective

Globally, respiratory syncytial virus (RSV) infection causes substantial morbidity in infants and young children, particularly those with specific risk factors (e.g., prematurity, chronic lung and congenital heart disease). Supportive measures are the mainstay of care for RSV-related disease. In the absence of medical treatments, RSV prophylaxis (RSVP) with palivizumab is recommended for high-risk patients to help reduce the risk of developing serious disease. Geographic distances, language and cultural barriers, and other factors can impede effective education of caregivers regarding the potential impact of RSV disease and benefits of RSVP compliance. We present our experiences developing successful Canadian RSVP programs, organized through a dedicated coordinator or small group of health care staff. These programs focus on identifying all infants and young children eligible for RSVP, effectively educating health care staff and family caregivers, developing educational tools that consider language and cultural factors, and interdisciplinary collaboration and networking throughout the health care system.

Strategies for reducing the risk of respiratory syncytial virus infection in infants and young children: a Canadian nurses' perspective

Respiratory syncytial virus (RSV) infections are prevalent globally and can cause substantial morbidity in infants and young children. The virus is easily transmitted by direct hand-to-hand contact and can lead to serious respiratory disease and hospitalization, particularly in premature infants and children with certain medical conditions. Educating families with young children, especially those in remote rural regions, regarding the potential adverse health outcomes of RSV infection and measures to reduce the risk of transmitting or acquiring RSV has been a key focus of the health care system in Canada. Geographic, cultural, and socioeconomic factors present formidable challenges to the execution of this endeavor. Therefore, it is critical to develop and systematically implement effective educational programs for both families and health care providers. In Canada, nurses play a critical role in education and counseling. In this review, we share our perspectives and suggest empirical practices that may be applicable worldwide.

Late preterm infants: near term but still in a critical developmental time period

Late preterm (LP) infants are defined as those born at 34-0/7 to 36-6/7 weeks' gestational age. LP infants were previously referred to as near term infants. The change in terminology resulted from the understanding that these infants are not fully mature and that the last 6 weeks of gestation represent a critical period of growth and development of the fetal brain and lungs, and of other systems. There is accumulating evidence of higher risks for health complications in these infants, including serious morbidity and a threefold higher infant mortality rate compared with term infants. This information is of critical importance because of its scientific merits and practical implications. However, it warrants a critical and balanced review, given the apparent overall uncomplicated outcome for the majority of LP infants. Others reviewed the characteristics of LP infants that predispose them to a higher risk of morbidity at the neonatal period. This review focuses on the long-term neurodevelopmental and respiratory outcomes, with the main aim to suggest putative prenatal, neonatal, developmental, and environmental causes for these increased morbidities. It demonstrates parallelism in the trajectories of pulmonary and neurologic development and evolution as a model for fetal and neonatal maturation. These may suggest the critical developmental time period as the common pathway that leads to the outcomes. Disruption in this pathway with potential long-term consequences in both systems may occur if the intrauterine milieu is disturbed. Finally, the review addresses the practical implications on perinatal and neonatal care during infancy and childhood.

Persistent recurring wheezing in the fifth year of life after laboratory-confirmed, medically attended respiratory syncytial virus infection in infancy

Background

Respiratory syncytial virus (RSV) infection in infancy is associated with subsequent recurrent wheezing.

Methods

A retrospective cohort study examined children born at ≥32 weeks gestation between 1996–2004. All children were enrolled in an integrated health care delivery system in Northern California and were followed through the fifth year of life. The primary endpoint was recurrent wheezing in the fifth year of life and its association with laboratory-confirmed, medically-attended RSV infection during the first year, prematurity, and supplemental oxygen during birth hospitalization. Other outcomes measured were recurrent wheezing quantified through outpatient visits, inpatient hospital stays, and asthma prescriptions.

Results

The study sample included 72,602 children. The rate of recurrent wheezing in the second year was 5.6% and fell to 4.7% by the fifth year. Recurrent wheezing rates varied by risk status: the rate was 12.5% among infants with RSV hospitalization, 8% among infants 32–33 weeks gestation, and 18% in infants with bronchopulmonary dysplasia. In multivariate analyses, increasing severity of respiratory syncytial virus infection was significantly associated with recurrent wheezing in year 5; compared with children without RSV infection in infancy, children who only had an outpatient RSV encounter had an adjusted odds ratio of 1.38 (95% CI,1.03–1.85), while children with a prolonged RSV hospitalization had an adjusted odds ratio of 2.59 (95% CI, 1.49–4.50).

Conclusions

Laboratory-confirmed, medically attended RSV infection, prematurity, and neonatal exposure to supplemental oxygen have independent associations with development of recurrent wheezing in the fifth year of life.

The use of humanized monoclonal antibodies for the prevention of respiratory syncytial virus infection

Monoclonal antibodies are widely used both in infants and in adults for several indications. Humanized monoclonal antibodies (palivizumab) have been used for many years for the prevention of respiratory syncytial virus infection in pediatric populations (preterm infants, infants with chronic lung disease or congenital heart disease) at high risk of severe and potentially lethal course of the infection. This drug was reported to be safe, well tolerated and effective to decrease the hospitalization rate and mortality in these groups of infants by several clinical trials. In the present paper we report the development and the current use of monoclonal antibodies for prophylaxis against respiratory syncytial virus.

Should respiratory care in preterm infants include prophylaxis against respiratory syncytial virus infection? The case in favour

Respiratory syncytial virus (RSV) is the most significant cause of acute respiratory tract infections (RTI) in infants and young children throughout the world. Preterm infants are at increased risk for severe RSV lower respiratory tract infection due to small lung volumes, a reduced lung surface area, small airways and an increased air space wall thickness. Additionally, the airways of preterm infants have been ventilated mechanically and suctioned and potentially damaged by many microtraumas with disruption of endothelial surfaces enabling pathogens to invade more easily. The immune system of preterm infants is immature resulting in low antibody titers (incomplete transplacental transfer of maternal antibodies) and a reduced cellular immunity with reduced viral clearance. Rehospitalization rates of preterm compared to term infants due to RSV infection are increased as are total morbidity and mortality associated with RSV disease. Palivizumab effectively reduces RSV related rehospitalisation in this high-risk population.

Medical retrieval and needs of infants with bronchiolitis: an analysis by gestational age

AIM

Viral bronchiolitis is the most common lower respiratory tract infection in children less than 12 months of age. Prematurity is an independent risk factor for disease severity. Many infected infants require hospitalisation and those living in regional centres frequently require transfer to metropolitan hospitals capable of providing assisted ventilation.

METHOD

We reviewed infants with bronchiolitis transported by the Victorian Newborn Emergency Transport Service between January 2003 and June 2007. We compared the clinical presentation and treatment required by infants born preterm with those of their term counterparts.

RESULTS

Of the 192 infants transported, 92 were born preterm. Preterm infants were younger at time of transport (mean post-menstrual age 41 weeks vs. 45 weeks) and were more likely to require invasive ventilation (60% vs. 32%, P < 0.001) and to receive a fluid bolus (47% vs. 34%, P = 0.04) when compared with infants who had been born at term. Apnoea, either as a presenting symptom or in combination with respiratory distress, was more common in the preterm group (70% vs. 36%, P < 0.001).

CONCLUSION

Higher illness severity should be anticipated in ex-preterm infants who present with bronchiolitis. Preterm infants with bronchiolitis are more likely to require invasive ventilation and fluid resuscitation than term infants, suggesting the need for a lower threshold for referral and medical retrieval.

Effects of parental and household smoking on the risk of respiratory syncytial virus (RSV) hospitalisation in late-preterm infants and the potential impact of RSV prophylaxis

OBJECTIVE

To assess the impact of household smoking and palivizumab prophylaxis on the risk of respiratory syncytial virus (RSV) hospitalisation in late-preterm (32-35 weeks' gestational age) infants.

METHODS

Familial smoking and other RSV risk factor data from the FLIP, FLIP-2 and IMpact studies and datasets from France, Germany and Italy, together with palivizumab prophylaxis data from the FLIP-2 and IMpact studies, were analysed using cross-correlation and Bayesian meta-analytical modelling employing Markov Chain Monte Carlo sampling.

RESULTS

There were 2.35 times (95% confidence interval [CI] 1.37-4.02) as many hospitalisations amongst infants from smoking compared with those from non-smoking families. Among non-prophylaxed infants, there were 2.53 times (95% CI 1.27-4.94) as many RSV hospitalisations from smoking than from non-smoking families and that excess hospitalisation was reduced to 1.03 times (95% CI 0.38-2.99) amongst prophylaxed infants. Familial smoking correlates significantly (p < 0.01) with other RSV risk factors: positive correlation with number of school-age siblings, history of family atopy, family wheeze and gestational age; negative correlation with birth weight and breast feeding.

CONCLUSIONS

Late-preterm infants from smoking families appear to be at heightened risk for severe RSV infection requiring hospitalisation of which the risk may be reduced with RSV prophylaxis.

Acute care utilization due to hospitalizations for pediatric lower respiratory tract infections in British Columbia, Canada

BACKGROUND

Pediatric LRTI hospitalizations are a significant burden on patients, families, and healthcare systems. This study determined the burden of pediatric LRTIs on hospital settings in British Columbia and the benefits of prevention strategies as they relate to healthcare resource demand.

METHODS

LRTI inpatient episodes for patients <19 years of age during 2008-2010 were extracted from the BC Discharge Abstract Database. The annual number of acute care beds required to treat pediatric LRTIs was estimated. Sub-analyses determined the burden due to infants <1 year of age and high-risk infants. Population projections were used to forecast LRTI hospitalizations and the effectiveness of public health initiatives to reduce the incidence of LRTIs to 2020 and 2030.

RESULTS

During 2008-2010, LRTI as the primary diagnosis accounted for 32.0 and 75.9% hospitalizations for diseases of the respiratory system in children <19 years of age and infants <1 year of age, respectively. Infants <1 year of age accounted for 47 and 77% hospitalizations due to pediatric LRTIs and pediatric LRTI hospitalizations specifically due to respiratory syncytial virus (RSV), respectively. The average length of stay was 3.1 days for otherwise healthy infants <1 year of age and 9.1 days for high-risk infants (P <0.0001). 73.1% pediatric LRTI hospitalizations occurred between November and April. Over the study timeframe, 19.6 acute care beds were required on average to care for pediatric LRTIs which increased to 64.0 beds at the peak of LRTI hospitalizations. Increases in LRTI bed-days of 5.5 and 16.2% among <19 year olds by 2020 and 2030, respectively, were predicted. Implementation of appropriate prevention strategies could cause 307 and 338 less LRTI hospitalizations in <19 year olds in 2020 and 2030, respectively.

CONCLUSION

Pediatric LRTI hospitalizations require significant use of acute care infrastructure particularly between November and April. Population projections show the burden may increase in the next 20 years, but implementation of effective public health prevention strategies may contribute to reducing the acute care demand and to supporting efforts for overall pediatric healthcare sustainability.

Burden of respiratory syncytial virus infection in young children

Respiratory syncytial virus (RSV) is the most frequent and important cause of lower respiratory tract infection in infants and children. It is a seasonal virus, with peak rates of infection occurring annually in the cold season in temperate climates, and in the rainy season, as temperatures fall, in tropical climates. High risk groups for severe RSV disease include infants below six mo of age, premature infants with or without chronic lung disease, infants with hemodynamically significant congenital heart disease, infants with immunodeficiency or cystic fibrosis, and infants with neuromuscular diseases. Mortality rates associated with RSV infection are generally low in previous healthy infants (below 1%), but increase significantly in children with underlying chronic conditions and comorbidities. Following early RSV lower respiratory tract infection, some patients experience recurrent episodes of wheezing mimicking early childhood asthma with persistence of lung function abnormalities until adolescence. There is currently no RSV vaccine available, but promising candidate vaccines are in development. Palivizumab, a monoclonal RSV antibody that is the only tool for immunoprophylaxis in high-risk infants, lowers the burden of RSV infection in certain carefully selected patient groups.

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.

Cost-effectiveness of palivizumab in infancy

Respiratory syncytial virus is the most common cause of bronchiolitis, a lower respiratory tract infection occurring in infancy. It is responsible for several rehospitalizations, substantial morbidity and occasional deaths in the UK every year. Palivizumab is a recombinant monoclonal antibody that has been shown to reduce hospitalizations in infected infants. It is licensed for high-risk infants, primarily those born pre-term or with chronic pulmonary or cardiac conditions. Palivizumab is expensive, but several economic analyses have determined highly discrepant costs. This article reviews the limitations of the available efficacy and economic data, and highlights problems in interpretation and extrapolation. We also present the results of a cost-effectiveness analysis relevant to populations of high-risk infants in the UK.

A comparative study of respiratory syncytial virus (RSV) prophylaxis in premature infants within the Canadian Registry of Palivizumab (CARESS)

We examined the dosing regimens, compliance, and outcomes of premature infants who received palivizumab within the Canadian Registry of Palivizumab (CARESS). Infants receiving ≥1 dose of palivizumab during the 2006-2011 respiratory syncytial virus (RSV) seasons were recruited across 30 sites. Respiratory illness events were captured monthly. Infants ≤32 completed weeks gestational age (GA) (Group 1) were compared to 33-35 completed weeks GA infants (Group 2) following prophylaxis. In total, 6,654 patients were analyzed (Group 1, n = 5,183; Group 2, n = 1,471). The mean GA was 29.9 ± 2.9 versus 34.2 ± 2.2 weeks for Groups 1 and 2, respectively. Group differences were significant (all p-values <0.05) for the following: proportion of males, Caucasians, siblings, multiple births, maternal smoking, smoking during pregnancy, household smokers, >5 household individuals, birth weight, and enrolment age. Overall, infants received 92.6 % of expected injections. Group 1 received significantly more injections, but a greater proportion of Group 2 received injections within recommended intervals. The hospitalization rates were similar for Groups 1 and 2 for respiratory illness (4.7 % vs. 3.7 %, p = 0.1) and RSV (1.5 % vs. 1.4 %, p = 0.3). Neither the time to first respiratory illness [hazard ratio = 0.9, 95 % confidence interval (CI) 0.7-1.2, p = 0.5] nor to first RSV hospitalization (hazard ratio = 1.3, 95 % CI 0.8-2.2, p = 0.3) were different. Compliance with RSV prophylaxis is high. Despite the higher number of palivizumab doses in infants ≤32 completed weeks GA, the two groups' respiratory illness and RSV-positive hospitalization rates were similar.

Ethical considerations and rationale of the MAKI trial: a multicenter double-blind randomized placebo-controlled trial into the preventive effect of palivizumab on recurrent wheezing associated with respiratory syncytial virus infection in children with a gestational age of 33-35 weeks

BACKGROUND

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is the most frequent cause of bronchiolitis during infancy. Long-term airway morbidity with recurrent post bronchiolitis wheezing (PBW) episodes, which are probably associated with respiratory infections, occurs in 30 to 70% of infants that were hospitalised with RSV LRTI.

METHODS

We set up a multicenter, placebo-controlled double-blind randomized clinical trial in healthy preterm infants born between 33 and 35 weeks gestational age (WGA). The children received either one-monthly intramuscular palivizumab or placebo injection during the RSV season with a minimum of 2 injections.

RESULTS

The primary objective was to determine the preventive effect of RSV immunoprophylaxis (palivizumab) on the development of recurrent wheezing during the first year of life. The primary outcome measure was the number of wheezing days during the first year of life as obtained by daily logs. As a secondary outcome nasal swabs were taken for viral analysis in case of respiratory symptoms. We will also examine wheezing at age 1, 3 and 6 years both reported by the parents and the general practitioner and quality of life as secondary outcomes. This trial is possible because RSV immunoprophylaxis, although effective in this population, is not completely used in the Netherlands due to its high costs.

CONCLUSION

The Institutional review board (IRB) concluded the study has high clinical relevance because the benefit of 50% chance of protection by palivizumab outweighs the risk of side adverse events due to intramuscular administration of placebo.

RSV hospitalisation and healthcare utilisation in moderately prematurely born infants

Respiratory syncytial virus (RSV) infection is associated with chronic respiratory morbidity in infants born very prematurely. Our aims were to determine if infants born moderately prematurely (32--35 weeks of gestation) who had had an RSV hospitalisation, compared to those who had not, had greater healthcare utilisation and related cost of care in the first 2 years. Two thousand and sixty-six eligible infants' records were examined to identify three groups: 20 infants admitted for an RSV lower respiratory tract infection (RSV), 30 admitted for another respiratory problem (other respiratory) and 108 admitted for a nonrespiratory problem/never admitted (non-respiratory).Healthcare utilisation was assessed by examining hospital and general practitioner records and cost of care calculated using the National Scheme of Reference costs and the British National Formulary prices. The mean cost of care in the RSV group (£12,505) was greater than the non-respiratory(£1,178) (95% CI for difference £5,015 to £17,639, p=00.002) and the other respiratory (£3,356) groups (95% CI for difference £2,963 to £15,606, p<0.001). The adjusted mean differences in the cost of care were £11,186 between the RSV and non-respiratory groups (95% CI £4,763 to £17,609) and £9,076 (95% CI £2,515 to £15,637) between the RSV and the other respiratory groups. Forty-two of 2,066 eligible infants had an RSV hospitalisation (2%);thus, assuming prophylaxis would reduce the hospitalisation rate by 50%, the number needed to treat was 98. In conclusion,RSV hospitalisation in moderately prematurely born infants is associated with increased health-related cost of care. Nevertheless, if RSV prophylaxis is to be cost effective,a high risk group of moderately prematurely born infants needs to be identified.

High risk for RSV bronchiolitis in late preterms and selected infants affected by rare disorders: a dilemma of specific prevention

Respiratory syncytial virus (RSV) is the most frequent aetiologic agent that causes bronchiolitis and lower respiratory tract infection in infants. These infections may be severe and even life-threatening in selected high-risk populations. Traditional, well-established, high-risk populations are preterm infants with or without chronic lung disease and children with congenital heart disease. For these children, RSV prophylaxis using palivizumab, a monoclonal anti-RSV humanised antibody against the F-protein of RSV, has proven safe and efficacious in preventing RSV-related hospitalisation. Recently, a number of rare medical conditions have been associated with the risk of severe RSV infections. Evidence of safety and efficacy of RSV prophylaxis in these populations is lacking. Given the low incidence of these conditions, randomised trials are not feasible. A practical, opinion-based approach to this dilemma is offered in this paper. It is proposed that these rare disorders may qualify for RSV prophylaxis if the association between a specific condition and the risk of severe RSV infection is confirmed in at least 3 independent publications, of which at least 1 includes a prospective cohort study. To facilitate pharmaco-economic analyses, at least one of the three studies must also report on the absolute risk of severe RSV infection in the specified illness. The authors believe that qualification criteria will enable caregivers to target RSV prophylaxis more effectively in children with rare conditions and the proposed approach provides direction for future epidemiological studies on the risk of severe RSV infection in children with these uncommon, medical illnesses.

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.

Cost-effectiveness analysis of palivizumab among pre-term infant populations covered by Medicaid in the United States

OBJECTIVE

Medicaid infants are at high risk of severe respiratory syncytial virus (RSV) disease. The study objective was to estimate the cost-effectiveness of palivizumab in a Medicaid population.

METHODS

A societal cost-utility analysis was conducted of prophylaxis with palivizumab vs no prophylaxis among four groups of premature infants: (1) <32 weeks gestational age (wGA) and ≤ 6 months chronologic age (CA); (2) 32-34 wGA, ≤ 3 months CA with 2009 American Academy of Pediatrics (AAP) risk factors (RF); (3) 32-35 wGA, ≤ 6 months CA with 2006 AAP RF; and (4) 32-35 wGA, ≤ 6 months CA with ≤ 1 RF. Full dosing of palivizumab was assumed throughout the RSV season (consistent with the FDA-approved label). All costs were in 2010 US dollars. The societal public payer spend for palivizumab was estimated using Medicaid reimbursement methodologies for the top 10 palivizumab-using states in 2010 minus mandatory manufacturer rebates. This study reports the incremental cost-effectiveness ratios (ICERs) in cost per quality-adjusted life-year (QALY) gained. Sensitivity and probabilistic analyses were also conducted.

RESULTS

Palivizumab saved costs and improved QALYs among infants <32 wGA. Palivizumab was cost-effective in infants 32-34 wGA with 2009 AAP RF ($16,037 per QALY) and in infants 32-35 wGA with 2006 AAP RF ($38,244 per QALY). The ICER for infants 32-35 wGA with ≤ 1 RF was $281,892 per QALY. Influential variables in the sensitivity analysis included the background rate of RSV hospitalization, the cost of palivizumab, and the efficacy of palivizumab.

KEY LIMITATIONS

These results are not generalizable to commercially insured infants or infants outside of the US.

CONCLUSIONS

This is the first cost-utility analysis of palivizumab in a Medicaid population. Palivizumab, when dosed consistent with the FDA-approved labeling, was either cost-saving or cost-effective among current guideline-eligible infants in the Medicaid population. Palivizumab did not demonstrate cost-effectiveness in 32-35 wGA infants with ≤ 1 RF.

Epidemiology of respiratory syncytial virus infection in preterm infants

This review focuses on the burden of respiratory syncytial virus (RSV) infection in preterm infants with and without chronic lung disease (bronchopulmonary dysplasia, BPD). The year-to-year and seasonal variations in RSV activity are key aspects of RSV epidemiology, and knowledge/monitoring of local RSV activity is mandatory for guidance of prophylaxis with the monoclonal antibodies palivizumab and in the near future motavizumab. Morbidity expressed in rates of hospitalizations attributable to RSV illness revealed a mean of 10 percent in preterm infants without and 19 percent (p=0.016) with BPD. Mortality rates diverged widely, and case fatality rates have been reported to range from 0 to 12 percent. The typical clinical picture of lower respiratory tract infection is not different in term and preterm infants, but rates of apnoeas are significantly increased in preterms, ranging from 4.9 to 37.5 percent with decreasing rates observed in more recent studies. Until a RSV vaccine is developed and will be available, prophylaxis with palivizumab is the only preventative strategy other than hand hygiene and contact measures that significantly reduces RSV hospitalization rates in preterm infants both with and without BPD.

Cost-effectiveness analysis of palivizumab as respiratory syncytial virus prophylaxis in preterm infants in Sweden

AIM

To investigate the cost-effectiveness of palivizumab vs. no prophylaxis for respiratory syncytial virus (RSV) infection in preterm infants in Sweden.

METHODS

A probabilistic Markov model was populated using a nationwide register linkage and data from the literature. Cost-effectiveness was investigated from a societal perspective over a lifetime for infants born at <29 weeks of gestation. Palivizumab was modelled using assumptions for its direct effect on RSV hospitalization risk and an indirect effect (via decreased RSV hospitalization) on subsequent asthma and mortality during the epidemic. Costs and effects were discounted by 3%.

RESULTS

In the base case, prophylaxis resulted in an additional 0.102 quality-adjusted life-year (QALY) at a cost of 20,000 SEK relative to no prophylaxis (incremental cost-effectiveness ratio [ICER] 195,000 SEK/QALY). The probability of prophylaxis being cost-effective was 99% at a willingness-to-pay of 500,000 SEK/QALY. Assumptions about a causal association between RSV infection and subsequent asthma had a moderate impact, while exclusion of the indirect prophylaxis effect on mortality increased the ICER to 492,000 SEK/QALY. When excluding both of these, prophylaxis was not cost-effective.

CONCLUSION

Based on a willingness-to-pay of 500,000 SEK/QALY, palivizumab was found to be cost-effective compared with no prophylaxis for infants born at <29 weeks if severe RSV infection was assumed to increase subsequent asthma or mortality risk.

Evaluation of protective efficacy of respiratory syncytial virus vaccine against A and B subgroup human isolates in Korea

Human respiratory syncytial virus (HRSV) is a significant cause of upper and lower respiratory tract illness mainly in infants and young children worldwide. HRSV is divided into two subgroups, HRSV-A and HRSV-B, based on sequence variation within the G gene. Despite its importance as a respiratory pathogen, there is currently no safe and effective vaccine for HRSV. In this study, we have detected and identified the HRSV by RT-PCR from nasopharyngeal aspirates of Korean pediatric patients. Interestingly, all HRSV-B isolates exhibited unique deletion of 6 nucleotides and duplication of 60 nucleotides in the G gene. We successfully amplified two isolates ('KR/A/09-8' belonging to HRSV-A and 'KR/B/10-12' to HRSV-B) on large-scale, and evaluated the cross-protective efficacy of our recombinant adenovirus-based HRSV vaccine candidate, rAd/3xG, by challenging the immunized mice with these isolates. The single intranasal immunization with rAd/3xG protected the mice completely from KR/A/09-8 infection and partially from KR/B/10-12 infection. Our study contributes to the understanding of the genetic characteristics and distribution of subgroups in the seasonal HRSV epidemics in Korea and, for the first time, to the evaluation of the cross-protective efficacy of RSV vaccine against HRSV-A and -B field-isolates.

Impact of respiratory syncytial virus: the nurse's perspective

Respiratory syncytial virus (RSV) is a highly contagious virus, and is the major cause of lower respiratory tract infections in infants and toddlers worldwide. RSV infection poses serious health risks to young children during the first 2 years of life. Several infant populations have been classified as high risk, and additional risk factors are known to increase the likelihood of severe RSV infection. Treatment for active RSV infection is limited to the symptoms of infection rather than the underlying cause; therefore, it is critical to reduce the transmission of RSV. As nurses, we highlight the importance of educating healthcare professionals, both in the hospital and community settings, as well as parents and other caregivers about the risks and outcomes associated with RSV infection, and necessary measures to decrease the risk of infection. We also highlight the importance of the successful identification of those children who are at high risk of RSV infection. RSV prophylaxis (RSVP) with palivizumab has been shown to improve clinical outcome in infants who are considered high risk compared with those who have not received RSVP. The failure of healthcare staff and primary caregivers to protect children against an RSV infection can have lasting detrimental effects on the health and lives of affected children and their families.

A decade of respiratory syncytial virus epidemiology and prophylaxis: translating evidence into everyday clinical practice

Respiratory syncytial virus (RSV) is a common infection in infancy, with nearly all children affected by two years of age. Approximately 0.5% to 2.0% of all children are hospitalized with lower respiratory tract disease, of which 50% to 90% have bronchiolitis and 5% to 40% have pneumonia. Morbidity and mortality are highest in children with nosocomial infection and in those with underlying medical illnesses such as cardiac and chronic lung disease. Aboriginal children residing in remote northern regions are specifically considered to be at high risk for hospitalization due to RSV infection. Thorough hand washing and health education are the principal strategies in primary prevention. In the absence of a vaccine, palivizumab prophylaxis is currently the best intervention to reduce the burden of illness and RSV-related hospitalization in high-risk children. Health care professionals should provide palivizumab prophylaxis cost effectively in accordance with recommendations issued by pediatric societies and national advisory bodies. The present article reviews the epidemiology of RSV infection and the short- and long-term impact of disease in high-risk infants and special populations. Prevention strategies and treatment are discussed based on the existing scientific evidence, and future challenges in the management of RSV infection are addressed.

The multicenter Italian birth cohort study on incidence and determinants of lower respiratory tract infection hospitalization in infants at 33 weeks GA or more: preliminary results

BACKGROUND

Respiratory syncytial virus (RSV) causes respiratory infections during the first year of life. Very premature infants have more severe diseases and also 'late preterm infants' may be more susceptible to the infection.

AIM OF THE STUDY

To evaluate in an Italian cohort the incidence and risk factors of severe hospitalized lower respiratory tract infection (LRTI) induced or not by RSV during the first year of life.

METHODS

A cohort of 33(+0d)-34(+6d) wGA newborns paired with two sex- and age-matched 35(+0d)-37(+6d) wGA and ≥ 38(+0d) wGA newborns were enrolled. Hospitalization for LRTI induced or not by RSV during the first year of life was assessed through phone interview at the end of the RSV season (November-March) and at the completion of the first year of life. The parents were asked to report hospitalization for any reason.

RESULTS

1064 neonates were enrolled (November 2009-October 2010), 697 had at least one phone follow-up by September 2010. Babies of 33(+0d)-34(+6d) wGA were more frequently conceived through assisted fertilization technologies, born from cesarean delivery had more frequently acute perinatal risk factors and were more frequently twins. After a mean 6 month-follow-up, we registered 29 hospitalizations for LRTI induced or not by RSV. Hospitalizations were slightly and non-significantly more frequent in 33(+0d)-37(+6d) wGA infants. The risk of hospitalization was significantly 60% reduced in breastfed babies and four folds significantly increased during the RSV season.

CONCLUSION

The very preliminary data of this ongoing study suggest that in 'late-preterm' infants some individual/environmental characteristics of the infants play a relevant role in determining the risk of severe RSV infection.

Are late preterm infants as susceptible to RSV infection as full term infants?

Preterm infants are at increased risk of being rehospitalised during the first few months of life with severe respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) that usually manifests as apnea and hypoxemia. This occurs more commonly in preterm infants < 33 weeks gestational age (GA), but recent studies demonstrate that late preterm infants (those born between 34 weeks and 0 days to 36 weeks and 6 days GA) are equally susceptible to RSV LRTI as those with lower GA. Factors associated with severe LRTI include immaturity of both the humoral and cell-mediated immune system and interrupted lung development prior to 36 weeks GA which results in lower functional residual capacity, reduced compliance, diminished forced expiratory air flow and impaired gas exchange. Morbidity and mortality are significantly increased in late preterms compared to their term counterparts. Prophylaxis with palivizumab against RSV infection seems to be crucial. Due to the large number of infants in this age group, additional risk factors have been identified in order to tailor palivizumab prophylaxis effectively to those at highest risk for severe RSV LRTI.

Respiratory outcomes, utilization and costs 12 months following a respiratory syncytial virus diagnosis among commercially insured late-preterm infants

OBJECTIVES

To determine, among a commercially-insured population of late-preterm infants, utilization of healthcare resources and costs during the 1 year following a diagnosis of respiratory syncytial virus lower respiratory infection (RSV LRI).

METHODS

Administrative claims for non-capitated, commercially-insured infants <1 year old were used to identify infants diagnosed with RSV LRI and unspecified bronchiolitis/pneumonia (UBP). Infants were stratified by the setting of diagnosis. Infants without evidence of RSV LRI or UBP were selected as a comparison group. Economic and clinical outcomes were analyzed descriptively using propensity score weighting and logged ordinary least squares models were used to examine the relationship between RSV and costs (adjusted to 2006 USD) incurred within 1 year of RSV LRI.

RESULTS

The majority of infants were 3 months or older at the time of RSV LRI or UBP diagnosis. The rate of wheezing was significantly greater for infants in the RSV LRI and UBP cohorts relative to the comparison group (p < 0.001). Infantile asthma rates were 6-9 times higher among RSV LRI and UBP infants than the comparison group. RSV LRI and UBP infants also had significantly more emergency department visits and outpatient visits than the comparison group. The marginal healthcare costs were significantly higher for RSV LRI inpatients ($24,027) and outpatients ($2703) infants than for the comparison group (all p < 0.001).

CONCLUSION

Commercially insured late-preterm infants with RSV infection are at high risk for recurrent wheezing and infantile asthma during the 1-year period after the initial episode and impose a significant economic burden to the healthcare system.