The Underrecognized Burden of Respiratory Syncytial Virus Among Infants Presenting to US Emergency Departments

Cost Savings Without Increased Risk of Respiratory Hospitalization for Preterm Children after the 2014 Palivizumab Policy Update

OBJECTIVES

 Our objective was to compare rates of hospitalizations for respiratory illnesses in preterm and full-term (FT) children for 4 years before and after the 2014 update to the American Academy of Pediatrics (AAP) respiratory syncytial virus (RSV) immunoprophylaxis guidance, which restricted eligibility among infants born at 29 to 34 weeks in the first winter and all preterm infants in the second winter after neonatal discharge.

STUDY DESIGN

 We conducted pre-post and interrupted time series analyses on claims data from a commercial national managed care plan. We compared the number of RSV and all respiratory hospital admissions in the first and second RSV seasons after neonatal discharge among a cohort of preterm children, regardless of palivizumab status, in the 4 years before and after the implementation of the 2014 palivizumab eligibility change. A FT group was included for reference.

RESULTS

 The cohort included 821 early preterm (EP, <29 weeks), 4,790 moderate preterm (MP, 29-34 weeks), and 130,782 FT children. Palivizumab use after the policy update decreased among MP children in the first and second RSV seasons after neonatal discharge, without any change in the odds of hospitalization with RSV or respiratory illness. For the EP group, there was no change in the rate of palivizumab or the odds of hospitalization with RSV or respiratory illness after the policy update. For the FT group, there was a slight decrease in odds of hospitalization post-2014 after the policy update. The interrupted time series did not reveal any secular trends over time in hospitalization rates among preterm children. Following the policy change, there were cost savings for MP children in the first and second RSV seasons, when accounting for the cost of hospitalizations and the cost of palivizumab.

CONCLUSION

 Hospitalizations for RSV or respiratory illness did not increase, and cost savings were obtained after the implementation of the 2014 AAP palivizumab prophylaxis policy.

KEY POINTS

· Palivizumab use decreased among children born moderate preterm (29 to34 weeks) after the 2014 palivizuamb policy update.. · There was no change in odds of hospitalization with respiratory syncitial virus or respiratory illness among preterm infants after the policy update when compared to before.. · There were cost savings, when accounting for the cost of hospitalizations and the cost of palivizumab, after the policy update among children born moderate preterm..

Low Levels of RSV Testing Among Adults Hospitalized for Lower Respiratory Tract Infection in the United States

INTRODUCTION

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection (LRTI)-related hospitalizations in older adults. Without RSV-specific treatment for adults, testing is uncommon, leading to potential underestimation of RSV incidence in real-world data studies. This study aimed to quantify the frequency of RSV testing during LRTI-related hospitalizations of older adults to inform interpretation of incidence estimates.

METHODS

Administrative and billing data for hospitalizations of adults aged ≥ 65 years with a primary or secondary diagnosis of LRTI during the 2016-2019 RSV seasons (October-April) were extracted from the US all-payer Premier Healthcare Database (PHD). Billing codes identified RSV tests administered during eligible hospitalizations. The proportion of LRTI-related hospitalizations with a billed RSV test was calculated for each hospital in PHD, and summarized descriptively by hospital bed size, teaching status, and population served.

RESULTS

Most of the 937 study hospitals performed RSV testing infrequently during LRTI hospitalization; median percentage of LRTI hospitalizations with RSV testing was 4.3%, and 78.4% of hospitals performed RSV testing in less than 25% of LRTI-related hospitalizations. RSV testing varied extensively by hospital type. Median percentage tested was significantly higher for hospitals with ≥ 200 beds (9.1%) versus < 200 beds (1.6%), for teaching (11.0%) versus non-teaching (2.5%) hospitals, and in urban (7.4%) versus rural (0.7%) settings. The median percentage of RSV testing increased over time, from 0.8% to 6.3% between the 2016/17 and 2018/19 seasons.

CONCLUSION

A small proportion of older adults hospitalized with LRTI are tested for RSV in US hospitals. Large variability occurs across hospital types. Consequently, retrospective database analyses likely result in a substantial underestimation of the true RSV-related hospitalization incidence. RSV incidence studies using real-world data need to assess for RSV testing frequency and adjust their results for under ascertainment associated with limited testing.

Perturbations in Respiratory Syncytial Virus Activity During the SARS-CoV-2 Pandemic

Respiratory syncytial virus (RSV) is a common cause of respiratory disease in all age groups, with young children and older adults experiencing the most severe illness. The coronavirus disease 2019 (COVID-19) pandemic resulted in striking changes in the activity of seasonal respiratory viruses, including RSV. After a period of suppression early in the pandemic, an interseasonal surge of RSV occurred in 2021. Viral activity was detected primarily in children and young adults after relaxation of public health measures, but without the usual proportional increases in infections and hospitalizations in older adults who were likely still adhering to stricter public health measures.

Systematic Literature Review of Respiratory Syncytial Virus Laboratory Testing Practices and Incidence in United States Infants and Children <5 Years of Age

Background

Respiratory syncytial virus (RSV) can cause serious illness in those aged <5 years in the United States, but uncertainty remains around which populations receive RSV testing. We conducted a systematic literature review of RSV testing patterns in studies published from 2000 to 2021.

Methods

Studies of RSV, medically attended RSV lower respiratory tract infections (LRTIs), and bronchiolitis were identified using standard methodology. Outcomes were clinical decisions to test for RSV, testing frequency, and testing incidence proportions in inpatient (IP), emergency department (ED), outpatient (OP), and urgent care settings.

Results

Eighty good-/fair-quality studies, which reported data from the period 1988–2020, were identified. Twenty-seven described the clinical decision to test, which varied across and within settings. Two studies reported RSV testing frequency for multiple settings, with higher testing proportions in IP (n = 2, range: 83%–85%, 1996–2009) compared with ED (n = 1, 25%, 2006–2009) and OP (n = 2, 15%–25%, 1996–2009). Higher RSV testing incidence proportions were observed among LRTI infant populations in the ED (n = 1, 74%, 2007–2008) and OP (n = 2, 54%–69%, 1995–2008). Incidence proportions in LRTI populations were not consistently higher in the IP setting (n = 13). Across studies and time, there was heterogeneity in RSV testing patterns, which may reflect varying detection methods, populations, locations, time periods, and healthcare settings.

Conclusions

Not all infants and children with LRTI are tested for RSV, highlighting underestimation of RSV burden across all settings.

Modelled estimates of hospitalisations attributable to respiratory syncytial virus and influenza in Australia, 2009-2017

Background

Respiratory syncytial virus (RSV) and influenza are important causes of disease in children and adults. In Australia, information on the burden of RSV in adults is particularly limited.

Methods

We used time series analysis to estimate respiratory, acute respiratory infection, pneumonia and influenza, and bronchiolitis hospitalisations attributable to RSV and influenza in Australia during 2009 through 2017. RSV and influenza‐coded hospitalisations in <5‐year‐olds were used as proxies for relative weekly viral activity.

Results

From 2009 to 2017, the estimated all‐age average annual rates of respiratory hospitalisations attributable to RSV and seasonal influenza (excluding 2009) were 54.8 (95% confidence interval [CI]: 20.1, 88.8) and 87.8 (95% CI: 74.5, 97.7) per 100,000, respectively. The highest estimated average annual RSV‐attributable respiratory hospitalisation rate per 100,000 was 464.2 (95% CI: 285.9, 641.2) in <5‐year‐olds. For seasonal influenza, it was 521.6 (95% CI: 420.9, 600.0) in persons aged ≥75 years. In ≥75‐year‐olds, modelled estimates were approximately eight and two times the coded estimates for RSV and seasonal influenza, respectively.

Conclusions

RSV and influenza are major causes of hospitalisation in young children and older adults in Australia, with morbidity underestimated by hospital diagnosis codes.

Predominant Bacterial and Viral Otopathogens Identified Within the Respiratory Tract and Middle Ear of Urban Australian Children Experiencing Otitis Media Are Diversely Distributed

Background

Otitis media (OM) is one of the most common infections in young children, arising from bacterial and/or viral infection of the middle ear. Globally, Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi) are the predominant bacterial otopathogens. Importantly, common upper respiratory viruses are increasingly recognized contributors to the polymicrobial pathogenesis of OM. This study aimed to identify predominant bacteria and viruses in the nasopharynx, adenoids and middle ears of peri-urban/urban South-East Queensland Australian children, with and without clinical history of chronic otitis media with effusion (COME) and/or recurrent acute otitis media (RAOM).

Methods

Sixty children, 43 diagnosed with OM and 17 controls with no clinical history of OM from peri-urban/urban South-East Queensland community were recruited to the study. Respiratory tract bacterial and viral presence were examined within nasopharyngeal swabs (NPS), middle ear effusions (MEE) and adenoids, using real-time polymerase chain reaction (RT-PCR) and bacterial culture.

Results

At least one otopathogen present was observed in all adenoid samples, 86.1% and 82.4% of NPS for children with and without OM, respectively, and 47.1% of the MEE from the children with OM. NTHi was the most commonly detected bacteria in both the OM and control cohorts within the adenoids (90.0% vs 93.8%), nasopharynx (67.4% vs 58.8%) respectively, and in the MEE (OM cohort 25.9%). Viruses were detected in all adenoid samples, 67.4% vs 47.1% of the NPS from the OM and control cohorts, respectively, and 37% of the MEE. Rhinovirus was the predominant virus identified in the adenoids (85.0% vs 68.8%) and nasopharynx (37.2% vs 41.2%) from the OM and control cohorts, respectively, and the MEE (19.8%).

Conclusions

NTHi and rhinovirus are predominant otopathogens within the upper respiratory tract of children with and without OM from peri-urban and urban South-East Queensland, Australia. The presence of bacterial otopathogens within the middle ear is more predictive of concurrent URT infection than was observed for viruses, and the high otopathogen carriage within adenoid tissues confirms the complex polymicrobial environment in children, regardless of OM history.

Unintended Consequences Following the 2014 American Academy of Pediatrics Policy Change for Palivizumab Prophylaxis among Infants Born at Less than 29 Weeks' Gestation

OBJECTIVE

The aim of this study is to compare outpatient respiratory syncytial virus (RSV) immunoprophylaxis (IP) use and relative RSV hospitalization (RSVH) rates for infants <29 weeks' gestational age (wGA) versus term infants before and after the 2014 American Academy of Pediatrics (AAP) policy change.

STUDY DESIGN

Infants were identified in the MarketScan Commercial and Multi-State Medicaid databases. Outpatient RSV IP receipt and relative <29 wGA/term hospitalization risks in 2012 to 2014 and 2014 to 2016 were assessed using rate ratios and a difference-in-difference model.

RESULTS

Outpatient RSV IP receipt by infants <29 wGA and aged <3 months in the Commercial and Medicaid populations and those aged 3 to <6 months in the Medicaid population declined after 2014. Relative RSVH risks for infants <29 wGA were numerically greater after 2014, with infants aged <3 months and Medicaid infants experiencing the greatest increases. Difference-in-difference results indicated a significantly increased relative risk of RSVH for infants <29 wGA versus term (both cohorts aged 0 to <6 months) in the Medicaid-insured population (1.68, p = 0.0054). A nonsignificant increase of similar magnitude occurred in the commercially insured population (1.57, p = 0.2867).

CONCLUSION

The 2014 policy change was associated with a decrease in RSV IP use and an increase in RSVH risk among otherwise healthy infants <29 wGA.

Calibration of Chronic Lung Disease Severity as a Risk Factor for Respiratory Syncytial Virus Hospitalization

BACKGROUND

Guidelines assume children with chronic lung disease (CLD) who require medical support within 6 months before the second respiratory syncytial virus (RSV) season remains at high risk of severe RSV disease. We determined the number of days since the last treatment (DSL) when the risk of RSV hospitalization among children with CLD becomes equivalent to the risk for those not qualified for immunoprophylaxis.

METHODS

The study cohort was assembled using Medicaid billing records from 1999 to 2010 linked to Florida and Texas birth certificate records. We developed DSL-trend discrete time logistic regression models within a survival analysis framework, adjusting for use of immunoprophylaxis, to compare the hospitalization risk of CLD infants at 4 age points to that of term infants at 1 month of age with siblings.

RESULTS

The study cohort included 858 830 healthy term and 5562 preterm infants with CLD. Among 1-month-old term infants, the RSV hospitalization risk averaged across all covariate strata was 14.8 (95% confidence interval [CI], 13.5-16.1) per 1000 patient season-months. Risk for preterm CLD children reached the threshold derived from term infants when DSL was 76 (95% CI, 22-198.5), 52 (95% CI, 6.5-123), 35 (95% CI, 0-93.5), and 12 (95% CI, 0-61.5) at the respective ages of 12, 15, 17.2, and 21 months.

CONCLUSIONS

The 180-day threshold used to define CLD severity at season start can be shortened to 120 days, 90 days, and 60 days for children with CLD at age 15, 17.2, and 21 months, respectively.

Increase in Detection of Respiratory Syncytial Virus Among Older Adults in Arizona : An Association With Changes in Testing Practices

OBJECTIVES

Respiratory syncytial virus (RSV) is a common cause of respiratory illness, health care visits, and hospitalizations. Arizona, which began conducting laboratory surveillance in 2004, has noted an increase in RSV cases (defined as a laboratory-positive result) among adults aged ≥65, concurrent with increasing reports from polymerase chain reaction (PCR) testing. We assessed whether the shift in the age distribution of reported RSV cases resulted from a change in RSV testing practices.

METHODS

We used data on laboratory-confirmed RSV cases reported during 2013-2017 from the statewide surveillance system to assess the frequency of test types (rapid antigen, immunofluorescence assay, PCR, and viral culture) by age groups across RSV seasons, and we used logistic regression to estimate changes in odds of receiving a PCR test. We used statewide emergency department hospital discharge data for the same period to assess testing practices regardless of test result.

RESULTS

The overall proportion of PCR tests among RSV cases increased significantly, from 22% in 2013 to 55% in 2017 (P < .001). The percentage of RSV cases among adults aged ≥65 also increased significantly, from 4% in 2013 to 11% in 2017 (P < .001) of RSV cases. Adults aged ≥65 had more than 8 times the odds of positive PCR results than children aged <5, both in crude (odds ratio [OR] = 8.8; 95% CI, 7.6-10.2) and season-adjusted (adjusted OR = 8.1; 95% CI, 7.0-9.5) models. Hospital discharge data corroborated increased RSV PCR usage from 2013 to 2017.

CONCLUSION

Increasing RSV rates among adults aged ≥65 are likely a result of changes in testing practices. This age group may need more targeted intervention and future vaccination.

Respiratory Syncytial Virus-Associated Hospitalization Rates among US Infants: A Systematic Review and Meta-Analysis

BACKGROUND

Although global reviews of infant RSV burden exist, none have summarized data from the United States or evaluated how RSV burden estimates are influenced by variations in study design.

METHODS

We performed a systematic literature review and meta-analysis of studies describing RSV-associated hospitalization rates among US infants and examined the impact of key study characteristics on these estimates.

RESULTS

We reviewed 3328 articles through August 14, 2020 and identified 25 studies with 31 unique estimates of RSV-associated hospitalization rates. Among US infants <1 year of age, annual rates ranged from 8.4 to 40.8 per 1000 with a pooled rate= 19.4 (95%CI: 17.9-20.9). Study type influenced RSV-associated hospitalization rates (P=.003), with active surveillance studies having pooled rates (11.0; 95%CI: 9.8-12.2) that were half that of studies based on administrative claims (21.4; 95%CI: 19.5-23.3) or modeling approaches (23.2; 95%CI: 20.2-26.2).

CONCLUSIONS

Applying our pooled rates to the 2020 US birth cohort suggests that 79,850 (95%CI: 73,680-86,020) RSV-associated infant hospitalizations occur each year. The full range of RSV-associated hospitalization rates identified in our review can better inform future evaluations of RSV prevention strategies. More research is needed to better understand differences in estimated RSV burden across study design.

Respiratory Syncytial Virus and All-Cause Bronchiolitis Hospitalizations Among Preterm Infants Using the Pediatric Health Information System (PHIS)

Background

In 2014, the American Academy of Pediatrics stopped recommending palivizumab to otherwise healthy 29–34 weeks’ gestational age (wGA) infants aged <12 months at respiratory syncytial virus (RSV) season start. Here, we compare the burden of RSV hospitalizations (RSVH) and all-cause bronchiolitis hospitalizations (BH) before and after 2014 among otherwise healthy 29–34 wGA infants hospitalized at ≤6 months of age.

Methods

A historical, observational cohort study was conducted to evaluate RSVH and BH in 29–34 wGA infants during the 2010–2017 RSV seasons using encounter data from 51 United States children’s hospitals that comprise the Pediatric Health Information System.

Results

The overall cohort included 67 570 RSVH out of 96 281 patients with BH. wGA was known for 22 937 RSVH and 33 289 BH. For 29–34 wGA infants, there were 8.7% and 14.2% RSVH before and after 2014, respectively (P < .0001). Intensive care unit admissions increased for RSVH (from 54.5% to 64.2%; P = .0002) and BH (from 46.7% to 54.5%; P = .0005) after controlling for sex, race, comorbidity, and cluster. The total cost of care increased for RSVH from $37 million to nearly $60 million.

Conclusions

RSVH, BH, and their severity increased among 29–34 wGA infants in the 3 RSV seasons following 2014.

Comparison of health care resource utilization among preterm and term infants hospitalized with Human Respiratory Syncytial Virus infections: A systematic review and meta-analysis of retrospective cohort studies

Introduction

Data on the variation in the medical resource utilization rate of Human Respiratory Syncytial Virus (HRSV) infected children by gestational age have recently been made available. This review aimed to determine whether prematurity is independently associated with the use of medical resources in hospitalized children for HRSV infections.

Methods

We conducted this systematic review on cohort studies published on the medical resources use in preterm and full-term patients hospitalized for confirmed HRSV infections. We searched PubMed, Embase, and Global Index medicus for eligible studies. The standardized mean difference (SMD) and Risk Ratio (RR) with their 95% confidence intervals (95% CI) were estimated as summary statistics with random effects meta-analysis. The overall results were adjusted to the common confounders by stratified analyses.

Results

A total of 14 articles (20 studies) were included. Compared to full-term, preterm hospitalized with HRSV infections had more frequent intensive care unit admission (RR = 2.6, 95% CI = 1.9–3.5), increased length of stay in hospital (SMD = 0.6, 95% CI = 0.5–0.8) and intensive care unit (SMD = 0.6, 95% CI = 0.4–0.8) and increased case fatality rate (RR = 6.9, 95% CI = 2.0–23.8). Mechanical ventilation utilization was more frequent in preterm children ≤ 2 years (RR = 15.5, 95% CI = 8.9–26.4) and those who did not receive prophylaxis against HRSV (RR = 15.9, 95% CI = 9.1–27.9)] than in full-term children. No differences were identified in the frequency of emergency department visits, oxygen utilization, and the age at the first HRSV episode between preterm and full-term infants.

Conclusions

Regardless of gestational age, preterm infants hospitalized for HRSV infections, especially those ≤ 2 years, have an increased frequency of use of health resources and poor outcomes compared to full-term infants. HRSV vaccine development programs for pregnant women should be accelerated.

Clinical trials registration

Review registration PROSPERO, CRD42019124375.

Expert consensus on palivizumab use for respiratory syncytial virus in developed countries

Respiratory syncytial virus (RSV) infection is a leading cause of hospitalisation in early childhood and palivizumab is the only licensed intervention for prevention. Palivizumab guidelines should reflect the latest evidence, in addition to cost-effectiveness and healthcare budgetary considerations. RSV experts from Europe, Canada and Israel undertook a systematic review of the evidence over the last 5 years and developed recommendations regarding prophylaxis in industrialised countries. Almost 400 publications were reviewed. This group recommended palivizumab for: preterm infants (<29 and ≤31 weeks gestational age [wGA] and ≤9 and ≤6 months of age, respectively; high-risk 32-35wGA), former preterm children ≤24 months with chronic lung disease/bronchopulmonary dysplasia, children ≤24 months with significant congenital heart disease; and other high-risk populations, such as children ≤24 months with Down syndrome, pulmonary/neuromuscular disorders, immunocompromised, and cystic fibrosis. Up to 5 monthly doses should be administered over the RSV season. It is our impression that the adoption of these guidelines would help reduce the burden of RSV.

Respiratory syncytial virus-associated hospitalisations in Australia, 2006-2015

OBJECTIVE

To estimate rates of respiratory syncytial virus (RSV)-associated hospitalisation across the age spectrum, and to identify groups at particular risk of serious RSV-associated disease.

DESIGN, SETTING AND PARTICIPANTS

Retrospective review of National Hospital Morbidity Database data for all RSV-associated hospitalisations in Australia, 2006-2015.

MAIN OUTCOMES AND MEASURES

RSV-coded hospitalisation rates by age, sex, Indigenous status, jurisdiction, and seasonality (month and year); hospital length of stay; in-hospital deaths.

RESULTS

During 2006-2015, there were 63 814 hospitalisations with an RSV-specific principal diagnostic code; 60 551 (94.9%) were of children under 5 years of age. The hospitalisation rate for children under 5 years was 418 per 100 000 population; for children under 6 months of age it was 2224 per 100 000 population; the highest rate was for infants aged 0-2 months (2778 per 100 000 population). RSV-coded hospitalisation rates were higher for adults aged 65 or more than for people aged 5-64 years (incidence rate ratio [IRR], 6.6; 95% CI, 6.2-7.1), and were also higher for Indigenous Australians than other Australians (IRR, 3.3; 95% CI, 3.2-3.5). A total of 138 in-hospital deaths were recorded, including 82 of adults aged 65 years or more (59%).

CONCLUSIONS

Prevention strategies targeting infants, such as maternal or early infant vaccination, would probably have the greatest impact in reducing RSV disease rates. Further characterisation of RSV disease epidemiology, particularly in older adults and Indigenous Australians, is needed to inform health care strategies.

Respiratory Syncytial Virus Hospitalizations among U.S. Preterm Infants Compared with Term Infants Before and After the 2014 American Academy of Pediatrics Guidance on Immunoprophylaxis: 2012-2016

OBJECTIVE

The objective of this study was to compare risk for respiratory syncytial virus (RSV) hospitalizations (RSVH) for preterm infants 29 to 34 weeks gestational age (wGA) versus term infants before and after 2014 guidance changes for immunoprophylaxis (IP), using data from the 2012 to 2016 RSV seasons.

STUDY DESIGN

Using commercial and Medicaid claims databases, infants born between July 1, 2011 and June 30, 2016 were categorized as preterm or term. RSVH during the RSV season (November-March) were identified for infants aged <6 months and rate ratios (RRs) for hospitalization comparing preterm and term infants were calculated. Difference-in-difference models were fit to evaluate the changes in hospitalization risks in preterm versus term infants from 2012 to 2014 seasons to 2014 to 2016 seasons.

RESULTS

In all seasons, preterm infants had higher RSVH rates than term infants. Seasonal RRs prior to the guidance change for preterm wGA categories versus term infants ranged from 1.6 to 3.4. After the guidance change, the seasonal RRs ranged from 2.6 to 5.6. In 2014 to 2016, the risk associated with prematurity of 29 to 34 wGA versus term was significantly higher than in 2012 to 2014 (P<0.0001 for commercial and Medicaid samples).

CONCLUSION

In infants aged <6 months, the risk for RSVH for infants 29 to 34 wGA compared with term infants increased significantly after the RSV IP recommendations became more restrictive.

Prevalence of infant bronchiolitis-coded healthcare encounters attributable to RSV

AIM

We sought to determine the proportion of bronchiolitis episodes attributable to respiratory syncytial virus (RSV) among ICD-9 coded infant bronchiolitis episodes which were tested for RSV.

METHODS

Bronchiolitis healthcare encounters were extracted from Kaiser Permanente Northern California databases for years 2006 to 2009. We used ICD-9 codes for bronchiolitis to capture bronchiolitis-related healthcare encounters including hospital admissions (Hospitalization), emergency department visits (EDV), and outpatient visits (OPV). We reported the monthly proportion of RSV-positive bronchiolitis episodes among tested bronchiolitis episodes. We used logistic regression to assess association between bronchiolitis episodes and patient demographic and health care characteristics. We also used logistic regression to assess association between decision to test and patient demographics and health care characteristics.

RESULTS

Among 10,411 ICD-9 coded infant bronchiolitis episodes, 29% were RSV tested. Fifty one percent of those tested were RSV positive. Between December and February, and in infants ≤6 months, the proportion of bronchiolitis episodes that were attributable to RSV was 77.2% among hospitalized episodes, 78.3% among EDV episodes, and 60.9% among OPV episodes, respectively. The proportion of RSV-positive bronchiolitis episodes varied based upon infant age at diagnosis, level of health care service used, and time of the year of the episode.

CONCLUSION

Estimation of the proportion of ICD-9 coded bronchiolitis episodes attributable to RSV is more specific when restricting to bronchiolitis episodes during peak months, younger infant age, and those requiring higher level of healthcare.

Is it RSV?

A study of infant bronchiolitis-coded episodes described the proportion of events attributable to respiratory syncytial virus (RSV) and demonstrated that episodes occurring during the peak months of winter viral season, among younger infants, and among those with higher levels of care, were more likely to be attributable to RSV.

Effectiveness of Respiratory Syncytial Virus Immunoprophylaxis in Reducing Bronchiolitis Hospitalizations Among High-Risk Infants

We sought to determine the real-world effectiveness of respiratory syncytial virus (RSV) immunoprophylaxis in a population-based cohort to inform policy. The study population included infants born during 1996-2008 and enrolled in the Kaiser Permanente Northern California integrated health-care delivery system. During the RSV season (November-March), the date of RSV immunoprophylaxis administration and the following 30 days were defined as RSV immunoprophylaxis protected period(s), and all other days were defined as unprotected period(s). Numbers of bronchiolitis hospitalizations were determined using International Classification of Diseases, Ninth Revision, codes during RSV season. We used a proportional hazards model to estimate risk of bronchiolitis hospitalization when comparing infants' protected period(s) with unprotected period(s). Infants who had ever received RSV immunoprophylaxis had a 32% decreased risk of bronchiolitis hospitalization (adjusted hazard ratio = 0.68, 95% confidence interval: 0.46, 1.00) when protected periods were compared with unprotected periods. Infants with chronic lung disease (CLD) had a 52% decreased risk of bronchiolitis hospitalization (adjusted hazard ratio = 0.48, 95% confidence interval: 0.25, 0.94) when protected periods were compared with unprotected periods. Under the new 2014 American Academy of Pediatrics (AAP) guidelines, 48% of infants eligible for RSV immunoprophylaxis on the basis of AAP guidelines in place at birth would no longer be eligible, but nearly all infants with CLD would remain eligible. RSV immunoprophylaxis is effective in decreasing hospitalization. This association is greatest for infants with CLD, a group still recommended for receipt of RSV immunoprophylaxis under the new AAP guidelines.

Association of Age With Risk of Hospitalization for Respiratory Syncytial Virus in Preterm Infants With Chronic Lung Disease

IMPORTANCE

It is unknown whether the age threshold (≤24 months) for preterm infants with chronic lung disease (CLD) to receive immunoprophylaxis for respiratory syncytial virus (RSV) as currently recommended by American Academy of Pediatrics guidelines correctly identified infants at higher risk for hospitalization for RSV.

OBJECTIVE

To determine the age when the risk of hospitalization for RSV among preterm infants with CLD becomes equivalent to the risk for healthy, 1-month-old term infants who do not qualify for immunoprophylaxis.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted of 1 018 593 healthy term infants and 5181 preterm infants with CLD using Medicaid billing records (Medicaid Analytic eXtract files) from January 1, 1999, to December 31, 2010, linked to Florida and Texas birth and death certificates.

EXPOSURES

Age-trend discrete time logistic regression models within a survival analysis framework were developed, adjusting for covariates including the use of immunoprophylaxis, to compare the risk of hospitalization of preterm infants (<32 weeks' gestational age) with CLD at 3 through 34 months of age with the risk of hospitalization of term infants (37-41 weeks' gestational age) at 1 month of age.

MAIN OUTCOMES AND MEASURES

Age at which risk of hospitalization for RSV among preterm infants with CLD equals the risk for healthy term infants at age 1 month.

RESULTS

The study cohort included 1 018 593 healthy term infants and 5181 preterm infants with CLD; because patients could reenter the cohort for a second or third season, the total study cohort consisted of 1 880 531 healthy term infant-seasons (926 206 girls and 954 325 boys; mean [SD] age at first season entry, 12.6 [9.6] months) and 8680 CLD infant-seasons (3519 girls and 5161 boys; mean [SD] age at first season entry, 15.1 [9.1] months). Among term infants with siblings, the risk of hospitalization for RSV averaged across all covariate strata was 9.0 (95% CI, 8.4-9.6) per 1000 patient season-months at 1 month of age. The risk of hospitalization for RSV among preterm infants with CLD became similar to that of 1-month-old term infants at an age of 18.5 months (95% CI, 15.6-22.8).

CONCLUSIONS AND RELEVANCE

The age threshold at which the risk of hospitalization for RSV among qualifying preterm infants with CLD approximates that of healthy term infants supports the current American Academy of Pediatrics practice guideline recommending RSV prophylaxis until a maximum of 24 months of age.

The 2014-2015 National Impact of the 2014 American Academy of Pediatrics Guidance for Respiratory Syncytial Virus Immunoprophylaxis on Preterm Infants Born in the United States

OBJECTIVE

This article aims to compare respiratory syncytial virus (RSV) immunoprophylaxis (IP) use and RSV hospitalization rates (RSVH) in preterm and full-term infants without chronic lung disease of prematurity or congenital heart disease before and after the recommendation against RSV IP use in preterm infants born at 29 to 34 weeks' gestational age (wGA).

STUDY DESIGN

Infants in commercial and Medicaid claims databases were followed from birth through first year to assess RSV IP and RSVH, as a function of infant's age and wGA. RSV IP was based on pharmacy or outpatient medical claims for palivizumab. RSVH was based on inpatient medical claims with a diagnosis of RSV.

RESULTS

Commercial and Medicaid infants 29 to 34 wGA represented 2.9 to 3.5% of all births. RSV IP use in infants 29 to 34 wGA decreased 62 to 95% (p < 0.01) in the 2014-2015 season relative to the 2013-2014 season. Compared with the 2013-2014 season, RSVH increased by 2.7-fold (p = 0.02) and 1.4-fold (p = 0.03) for infants aged <3 months and 29 to 34 wGA in the 2014-2015 season with commercial and Medicaid insurance, respectively. In the 2014-2015 season, RSVH for infants 29 to 34 wGA were two to seven times higher than full-term infants without high-risk conditions.

CONCLUSION

Following the 2014 RSV IP guidance change, RSV IP use declined and RSVH increased among infants born at 29 to 34 wGA and aged <3 months.

The 2014-2015 National Impact of the 2014 American Academy of Pediatrics Guidance for Respiratory Syncytial Virus Immunoprophylaxis on Preterm Infants Born in the United States

OBJECTIVE

This article aims to compare respiratory syncytial virus (RSV) immunoprophylaxis (IP) use and RSV hospitalization rates (RSVH) in preterm and full-term infants without chronic lung disease of prematurity or congenital heart disease before and after the recommendation against RSV IP use in preterm infants born at 29 to 34 weeks' gestational age (wGA).

STUDY DESIGN

Infants in commercial and Medicaid claims databases were followed from birth through first year to assess RSV IP and RSVH, as a function of infant's age and wGA. RSV IP was based on pharmacy or outpatient medical claims for palivizumab. RSVH was based on inpatient medical claims with a diagnosis of RSV.

RESULTS

Commercial and Medicaid infants 29 to 34 wGA represented 2.9 to 3.5% of all births. RSV IP use in infants 29 to 34 wGA decreased 62 to 95% (p < 0.01) in the 2014-2015 season relative to the 2013-2014 season. Compared with the 2013-2014 season, RSVH increased by 2.7-fold (p = 0.02) and 1.4-fold (p = 0.03) for infants aged <3 months and 29 to 34 wGA in the 2014-2015 season with commercial and Medicaid insurance, respectively. In the 2014-2015 season, RSVH for infants 29 to 34 wGA were two to seven times higher than full-term infants without high-risk conditions.

CONCLUSION

Following the 2014 RSV IP guidance change, RSV IP use declined and RSVH increased among infants born at 29 to 34 wGA and aged <3 months.

Respiratory syncytial virus hospitalization risk in the second year of life by specific congenital heart disease diagnoses

Children with hemodynamically significant congenital heart disease (CHD) are at elevated risk of morbidity and mortality due to respiratory syncytial virus (RSV) disease compared to their healthy peers. Previous studies have demonstrated lower RSV hospitalization risk among all children with CHD at 12-23 months of age versus 0-11 months of age. However, RSV hospitalization risk at 12-23 months of age by specific CHD diagnosis has not been characterized. Both case-control and cohort studies were conducted using data from the US National Inpatient Sample from 1997 to 2013 to characterize relative risk of RSV hospitalization among children 12-23 months of age with CHD. Related CHD diagnoses were combined for analysis. Hospitalizations for RSV and unspecified bronchiolitis were described by length of stay, mechanical ventilation use, mortality, and total charges. Over the 17-year period, 1,168,886 live birth hospitalizations with CHD were identified. Multiple specific CHD conditions had an elevated odds ratio or relative risk of RSV hospitalization. Mean total RSV hospitalization charges were significantly higher among children with CHD relative to those without CHD ($19,650 vs $7,939 in 2015 dollars) for this period. Compared to children without CHD, children with Ebstein's anomaly, transposition of the great arteries, aortic stenosis, heterotaxia, and aortic arch anomalies had 367-, 344-, 203-, 117- and 47-fold increased risk of inpatient RSV mortality, respectively. Unspecified bronchiolitis hospitalization odds and relative risk across CHD diagnoses were similar to those observed with RSV hospitalization; however, unspecified bronchiolitis hospitalizations were associated with shorter mean days of stay and less frequently associated with mechanical ventilation or mortality. Among children with more severe CHD diagnoses, RSV disease remains an important health risk through the second year of life. These data can help inform decisions regarding interventions to protect children with CHD from severe RSV disease during their second year of life.

Respiratory syncytial virus hospitalization outcomes and costs of full-term and preterm infants

OBJECTIVE

Infection with respiratory syncytial virus (RSV), which causes lower respiratory tract infections, is the leading cause of hospitalization among children <1 year old in the United States. Risk factors for RSV hospitalization include premature birth and younger chronologic age, along with several comorbid conditions. However, in terms of RSV hospitalization costs, premature infants are rarely studied separately from full-term infants. The objective of this study is to describe the cost and severity of RSV hospitalizations among preterm and full-term infants without chronic lung disease or other high-risk conditions.

STUDY DESIGN

This analysis used Truven Health Market Scan Multi-State Medicaid and Commercial Claims and Encounters databases, which contain a combined 4 million births from 2003 to 2013. Infants with comorbid conditions associated with increased risk for RSV infection were excluded. Infants were classified as preterm (<29, 29-30, 31-32, 33-34 and 35-36 weeks' gestational age (wGA)) or full term based on diagnostic coding. Health-care claims during the first year of life were evaluated for RSV hospitalizations, defined as inpatient claims with a diagnosis code for RSV in any position. Costs of RSV hospitalizations were captured and reported in 2014 USD. Inpatient claims for RSV hospitalizations were evaluated for the presence of codes indicating admission to the intensive care unit (ICU), use of mechanical ventilation (MV) and length of stay. These three measures were used to describe hospital severity. Chronologic age at the time of RSV hospitalization was also captured. Data were summarized and no statistical comparisons were conducted.

RESULTS

There were 1 683 188 infants insured through Medicaid and 1 663 832 infants insured through commercial plans born from 1 July 2003 to 30 June 2013. Of those, 10.8 and 8.8% in each database, respectively, were born prematurely. There were 29 967 Medicaid-insured infants and 16 310 commercially insured infants with an RSV hospitalization during their first year of life. Mean first-year RSV hospitalization costs were higher for preterm infants, ranging from $8324 and $10 570 for full-term infants to $15 839 and $19 931 for preterm infants 33-34 wGA, and to $39 354 and $40 813 for preterm infants <29 wGA, among Medicaid-insured and commercially insured infants, respectively. RSV hospitalizations also tended to be more severe among preterm infants, with longer lengths of stay, a higher proportion of infants admitted to the intensive care unit (ICU) and increased use of MV compared with full-term infants. Mean costs of RSV hospitalizations with a PICU admission ranged from approximately $35 000 to $89 000. In both Medicaid and commercial groups, costs were greater for infants hospitalized at <90 days of age compared with older infants.

CONCLUSIONS

Infants who were born prematurely and those hospitalized at <90 days of age have more costly and more severe RSV hospitalizations during the first year of life. These findings demonstrate important differences in the costs and severity of first-year RSV hospitalizations of premature and full-term infants. These differences are likely to be obscured in combined analysis, in which full-term infants predominate. Clinical guidelines and health-care policies relating to RSV would benefit from the availability of data obtained from separate analyses of these two infant subgroups.

Trends in Respiratory Syncytial Virus and Bronchiolitis Hospitalization Rates in High-Risk Infants in a United States Nationally Representative Database, 1997-2012

Background

Respiratory syncytial virus (RSV) causes significant pediatric morbidity and is the most common cause of bronchiolitis. Bronchiolitis hospitalizations declined among US infants from 2000‒2009; however, rates in infants at high risk for RSV have not been described. This study examined RSV and unspecified bronchiolitis (UB) hospitalization rates from 1997‒2012 among US high-risk infants.

Methods

The Kids’ Inpatient Database (KID) infant annual RSV (ICD-9 079.6, 466.11, 480.1) and UB (ICD-9 466.19, 466.1) hospitalization rates were estimated using weighted counts. Denominators were based on birth hospitalizations with conditions associated with high-risk for RSV: chronic perinatal respiratory disease (chronic lung disease [CLD]); congenital airway anomalies (CAA); congenital heart disease (CHD); Down syndrome (DS); and other genetic, metabolic, musculoskeletal, and immunodeficiency conditions. Preterm infants could not be identified. Hospitalizations were characterized by mechanical ventilation, inpatient mortality, length of stay, and total cost (2015$). Poisson and linear regression were used to test statistical significance of trends.

Results

RSV and UB hospitalization rates were substantially elevated for infants with higher-risk CHD, CLD, CAA and DS without CHD compared with all infants. RSV rates declined by 47.0% in CLD and 49.7% in higher-risk CHD infants; no other declines in high-risk groups were observed. UB rates increased in all high-risk groups except for a 22.5% decrease among higher-risk CHD. Among high-risk infants, mechanical ventilation increased through 2012 to 20.4% and 13.5% of RSV and UB hospitalizations; geometric mean cost increased to $31,742 and $25,962, respectively, and RSV mortality declined to 0.9%.

Conclusions

Among high-risk infants between 1997 and 2012, RSV hospitalization rates declined among CLD and higher-risk CHD infants, coincident with widespread RSV immunoprophylaxis use in these populations. UB hospitalization rates increased in all high-risk groups except higher-risk CHD, suggesting improvement in the health status of higher-risk CHD infants, potentially due to enhanced surgical interventions. Mechanical ventilation use and RSV and UB hospitalization costs increased while RSV mortality declined.