Österreichische Gesellschaft für Kinder- und Jugendheilkunde (ÖGKJ). Konsensuspapier zur Prophylaxe der RSV-Infektion mit Palivizumab und Post-RSV-Atemwegserkrankung

Predictors of RSV LRTI Hospitalization in Infants Born at 33 to 35 Weeks Gestational Age: A Large Multinational Study (PONI)

BACKGROUND

Preterm infants are at high risk of developing respiratory syncytial virus (RSV)-associated lower respiratory tract infection (LRTI). This observational epidemiologic study evaluated RSV disease burden and risk factors for RSV-associated LRTI hospitalization in preterm infants 33 weeks+0 days to 35 weeks+6 days gestational age not receiving RSV prophylaxis.

METHODS

Preterm infants ≤6 months of age during RSV season (1 October 2013-30 April 2014) were followed at 72 sites across 23 countries from September 2013-July 2014 (study period). RSV testing was performed according to local clinical practice. Factors related to RSV-associated hospitalization for LRTI were identified using multivariable logistic regression with backward selection.

RESULTS

Of the 2390 evaluable infants, 204 and 127 were hospitalized for LRTI during the study period and RSV season, respectively. Among these subjects, 64/204 and 46/127, respectively, were hospitalized for confirmed RSV LRTI. Study period and RSV season normalized RSV hospitalization rates (per 100 infant years) were 4.1 and 6.1, respectively. Factors associated with an increased risk of RSV-related LRTI hospitalization in multivariable analyses were smoking of family members (P<0.0001), non-hemodynamically significant congenital heart disease diagnosis (P = 0.0077), maternal age of ≤25 years at delivery (P = 0.0009), low maternal educational level (P = 0.0426), household presence of children aged 4 to 5 years (P = 0.0038), age on 1 October ≤3 months (P = 0.0422), and presence of paternal atopy (P<0.0001).

CONCLUSIONS

During the 2013-2014 RSV season across 23 countries, for preterm infants 33-35 weeks gestation ≤6 months old on 1 October not receiving RSV prophylaxis, confirmed RSV LRTI hospitalization incidence was 4.1 per 100 infant years during the study period and 6.1 per 100 infant years during the RSV season. This study enhances the findings of single-country studies of common risk factors for severe RSV infection in preterm infants and suggests that combinations of 4-6 risk factors may be used to accurately predict risk of RSV hospitalization. These findings may be useful in the identification of infants most at risk of severe RSV infection.

Respiratory syncytial virus prophylaxis in Down syndrome: a prospective cohort study

BACKGROUND AND OBJECTIVES

Children with Down syndrome (DS) are at significant risk for respiratory syncytial virus (RSV) infection and related hospitalization. We compared hospitalization rates due to respiratory tract infection in children with DS aged <2 years who prospectively received palivizumab during the RSV season with a previously published, similar untreated DS birth cohort.

METHODS

A total of 532 children with DS who prospectively received palivizumab were assembled from the prospective Canadian RSV Evaluation Study of Palivizumab registry between 2005 and 2012. The untreated group included 233 children with DS derived from a nationwide Dutch birth cohort from 2003 to 2005. Events during the RSV seasons were counted. Poisson regression analysis was performed to compare incidence rate ratios (95% confidence intervals [CIs]) between groups while controlling for observation length and known risk factors for severe RSV infection.

RESULTS

In total, 31 (23 untreated, 8 treated) RSV-related hospitalizations were documented. The adjusted risk of RSV-related hospitalizations was higher in untreated subjects than in palivizumab recipients (incidence rate ratio 3.63; 95% CI, 1.52-8.67). The adjusted risk of hospitalization for all respiratory tract infection (147 events; 73 untreated, 74 treated) was similar (incidence rate ratio untreated versus palivizumab 1.11; 95% CI, 0.80-1.55).

CONCLUSIONS

These results suggest that palivizumab is associated with a 3.6-fold reduction in the incidence rate ratio for RSV-related hospitalization in children with DS during the first 2 years of life. A randomized trial is needed to determine the efficacy of RSV immunoprophylaxis in this specific high-risk patient population.

Respiratory-related hospitalizations following prophylaxis in the Canadian registry for palivizumab (2005-2012) compared to other international registries

Respiratory syncytial virus (RSV) infection occurs commonly in infants aged ≤2 years, and severe infection results in hospitalization with accompanying morbidity and mortality. Palivizumab has been available for prophylaxis for the past 15 years. Prospective data on patients who received palivizumab from 2005 to 2012 has been assembled in the Canadian registry (CARESS) to document utilization, compliance, and health outcomes in both hospital and community settings. Long-term data is necessary to evaluate the impact of palivizumab on the incidence of RSV infections, minimize healthcare resources, and identify which infant subpopulations are receiving prophylaxis. A database search was also conducted for similar information from published registries, and hospitalization rates were compared to results from randomized clinical trials (RCTs).Overall hospitalization rates (percent; range) for respiratory-related illnesses and RSV-specific infection in infants who meet standard indications for prophylaxis were 6.6 (3.3-7.7) and 1.55 (0.3-2.06), respectively, in CARESS, which closely aligns with registry data from 4 other countries, despite the former comprising the largest cohort of complex patients internationally. Overall RSV-related hospitalization rates were lower across registries compared to equivalent patients in RCTs. Registry data provides valuable information regarding real-world experience with palivizumab, while facilitating the genesis of new research themes.

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.

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.

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.

The impact of prophylaxis on paediatric intensive care unit admissions for RSV infection: a retrospective, single-centre study

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections and hospitalizations in children aged < 2 years. The aim of this retrospective, single-centre study was to examine the characteristics of patients admitted to a paediatric intensive care unit (PICU) with RSV infection following the implementation of a RSV prophylaxis programme. Electronic hospital medical records of all PICU admissions for RSV infection were searched from 2003 to 2009. Data on baseline demographics, underlying disease, criteria for hospitalization, respiratory diagnosis and management, complications and palivizumab prophylaxis were collected. A total of 181 patients were admitted with RSV infection, accounting for 5.7% of all admissions. Eighty-four percent were ≤ 2 years of age. Majority (70.2%) had no underlying medical illness, and 79.6% received antibiotics as part of their medical treatment. Comparison of children aged ≤ 2 years and those >2 years revealed that fewer of the younger cohort (20.4% versus 79.3%; p < 0.001) had an underlying medical condition. RSV infection occurred in 3.3% (n = 6) children who had received palivizumab prophylaxis, and there were two deaths. The results indicate that > 88% of all PICU admissions would not qualify for RSV prophylaxis under our established guidelines and 66% of the children aged ≤ 2 years were > 36 weeks gestation and are not currently targeted for prophylaxis. The number of high-risk infants admitted to PICU with RSV infection has likely plateaued, and further reductions in admission rates may only be realised with the use of universal, vaccine immunization programmes.

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.

Severe respiratory syncytial virus (RSV) infection in infants with neuromuscular diseases and immune deficiency syndromes

Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infection (LRTI) in infants and children. There is growing evidence of severe RSV disease in infants with neuromuscular diseases and immune deficiency syndromes. Factors predisposing to a more severe course of RSV disease in neuromuscular diseases include the impaired ability to clear secretions from the airways due to ineffective cough, respiratory muscle weakness, high prevalence of gastro-oesophageal reflux and swallowing dysfunction which leads to aspiration. Similarly, pulmonary disease is a common presenting feature and complication of T-cell immunodeficiency. Infants with severe congenital and acquired immune deficiency syndromes may demonstrate prolonged viral shedding in RSV LRTI and are reported to have increased morbidity and mortality associated with RSV infection. Although not indicated in most guideline statements, palivizumab prophylaxis for these uncommon underlying conditions is under consideration by clinicians. Prospective studies are needed to determine the burden of RSV disease in these children.