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

Mechanisms of Lung and Intestinal Microbiota and Innate Immune Changes Caused by Pathogenic Enterococcus Faecalis Promoting the Development of Pediatric Pneumonia

Bacterial pneumonia is the main cause of illness and death in children under 5 years old. We isolated and cultured pathogenic bacteria LE from the intestines of children with pneumonia and replicated the pediatric pneumonia model using an oral gavage bacterial animal model. Interestingly, based on 16srRNA sequencing, we found that the gut and lung microbiota showed the same imbalance trend, which weakened the natural resistance of this area. Further exploration of its mechanism revealed that the disruption of the intestinal mechanical barrier led to the activation of inflammatory factors IL-6 and IL-17, which promoted the recruitment of ILC-3 and the release of IL-17 and IL-22, leading to lung inflammation. The focus of this study is on the premise that the gut and lung microbiota exhibit similar destructive changes, mediating the innate immune response to promote the occurrence of pneumonia and providing a basis for the development and treatment of new drugs for pediatric pneumonia.

Bronchiolitis hospitalizations in rural New England: clues to disease prevention

Background:

An improved understanding of the clinico-epidemiology of bronchiolitis hospitalizations, a clinical surrogate of respiratory syncytial virus (RSV) disease, is critical to inform public health strategies for mitigating the in-patient burden of bronchiolitis in early life.

Methods:

A retrospective chart review was conducted of all bronchiolitis first admissions (N = 295) to the Children’s Hospital at Dartmouth-Hitchcock, CHaD, between 1 November 2010 and 31 October 2017 using the relevant International Classification of Diseases (ICD)-9 and ICD-10 codes for this illness. Abstracted data included laboratory confirmation of RSV infection, severity of illness, duration of hospitalization, age at admission in days, weight at admission, prematurity, siblings, and relevant medical pre-existing conditions.

Results:

Admissions for bronchiolitis were strongly associated with age of the child, the calendar month of an infant’s birth, and the presence of older children in the family. Medical risk factors associated with admission included premature birth and underlying cardiopulmonary disease.

Conclusion:

The very early age of hospitalization emphasizes the high penetration of RSV in the community, by implication the limited protection afforded by maternal antibody, and the complexity of protecting infants from this infection.

Plain Language Summary

Although risks for respiratory syncytial virus (RSV)/bronchiolitis hospitalization are well described, few studies have examined, with precision, the age-related frequency and severity of RSV/bronchiolitis. We also explore the implications of RSV clinico-epidemiology for our understanding of the pathogenesis of the disease and development of optimal approaches to prevention.

Assessing the strength of evidence for a causal effect of respiratory syncytial virus lower respiratory tract infections on subsequent wheezing illness: a systematic review and meta-analysis

Background

Although a positive association has been established, it is unclear whether lower respiratory tract infections (LRTIs) with respiratory syncytial virus (RSV) cause chronic wheezing illnesses. If RSV-LRTI were causal, we would expect RSV-LRTI prevention to reduce the incidence of chronic wheezing illnesses in addition to reducing acute disease. We aimed to evaluate the strength of evidence for a causal effect of RSV-LRTI on subsequent chronic wheezing illness to inform public health expectations for RSV vaccines.

Methods

We did a systematic review and meta-analysis of observational studies evaluating the association between RSV-LRTI and subsequent wheezing illness (exposure studies) and studies evaluating the association between RSV immunoprophylaxis and subsequent wheezing illness (immunoprophylaxis studies). Exposure studies were included if the exposure group members had an LRTI with laboratory-confirmed RSV and if the exposure ascertainment period began before 2 years of age and ended before 5 years of age. We required a wash-out period of more than 30 days between the index RSV-LRTI and the outcome measurement to allow for resolution of the acute illness. Comparisons between RSV-LRTI and non-RSV-LRTI were not included. Immunoprophylaxis studies were included if they measured the association with subsequent wheezing illness relative to a control group, either in a randomised controlled trial (RCT) or an observational design. For the immunoprophylaxis drugs in question, we required evidence of efficacy in targeting RSV-LRTI from at least one RCT to ensure biological plausibility. All variations of wheezing illness were combined into a single outcome that refers broadly to asthma or any other respiratory illness with wheezing symptoms. Ovid MEDLINE and Embase databases were searched from inception up to Aug 28, 2018. We evaluated whether data from exposure studies could provide evidence against the most viable non-causal theory that RSV-LRTI is a marker of respiratory illness susceptibility rather than a causal factor. Additionally, we tested whether RSV immunoprophylaxis reduces the odds of subsequent wheezing illnesses. We used a random-effects modelling framework and, to accommodate studies providing multiple correlated estimates, robust variance estimation meta-regressions. Meta-regression coefficients (b) quantify differences between exposure and comparator groups on the log_e odds ratio (log_e OR) scale.

Findings

From 14 235 records we identified 57 eligible articles that described 42 studies and provided 153 effect estimates. 35 studies estimated the direct effect of RSV-LRTI on wheezing illnesses (exposure studies) and eight evaluated the effect of RSV immunoprophylaxis (immunoprophylaxis studies). Exposure studies that adjusted for genetic influences yielded a smaller mean adjusted OR estimate (aOR₊ 2·45, 95% CI 1·23–4·88) compared with those that did not (4·17, 2·36–7·37), a significant difference (b 0·53, 95% CI 0·04–1·02). Infants who were not protected with RSV immunoprophylaxis tended to have higher odds of subsequent wheezing illness, as we would expect if RSV-LRTI were causal, but the effect was not significant (OR₊ 1·21, 95% CI 0·73–1·99). There was generally a high threat of confounding bias in the observational studies. Additionally, in both the observational studies and immunoprophylaxis RCTs, there was high risk of bias due to missing outcome data.

Interpretation

Our findings, limited to exposure and immunoprophylaxis studies, do not support basing policy decisions on an assumption that prevention of RSV-LRTI will reduce recurrent chronic wheezing illnesses.

Funding

Bill & Melinda Gates Foundation.

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.

Cost of Respiratory Syncytial Virus-Associated Acute Lower Respiratory Infection Management in Young Children at the Regional and Global Level: A Systematic Review and Meta-Analysis

Background

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory infection (ALRI) in young children aged &lt;5 years.

Methods

We aimed to identify the global inpatient and outpatient cost of management of RSV-ALRI in young children to assist health policy makers in making decisions related to resource allocation for interventions to reduce severe morbidity and mortality from RSV in this age group. We searched 3 electronic databases including Global Health, Medline, and EMBASE for studies reporting cost data on RSV management in children under 60 months from 2000 to 2017. Unpublished data on the management cost of RSV episodes were collected through collaboration with an international working group (RSV GEN) and claim databases.

Results

We identified 41 studies reporting data from year 1987 to 2017, mainly from Europe, North America, and Australia, covering the management of a total of 365 828 RSV disease episodes. The average cost per episode was €3452 (95% confidence interval [CI], 3265–3639) and €299 (95% CI, 295–303) for inpatient and outpatient management without follow-up, and it increased to €8591(95% CI, 8489–8692) and €2191 (95% CI, 2190–2192), respectively, with follow-up to 2 years after the initial event.

Conclusions

Known risk factors (early and late preterm birth, congenital heart disease, chronic lung disease, intensive care unit admission, and ventilator use) were associated with €4160 (95% CI, 3237–5082) increased cost of hospitalization. The global cost of inpatient and outpatient RSV ALRI management in young children in 2017 was estimated to be approximately €4.82 billion (95% CI, 3.47–7.93), 65% of these in developing countries and 55% of global costs accounted for by hospitalization. We have demonstrated that RSV imposed a substantial economic burden on health systems, governments, and the society.

Does respiratory syncytial virus lower respiratory illness in early life cause recurrent wheeze of early childhood and asthma? Critical review of the evidence and guidance for future studies from a World Health Organization-sponsored meeting

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection (LRTI) and hospitalization in infants and children globally. Many observational studies have found an association between RSV LRTI in early life and subsequent respiratory morbidity, including recurrent wheeze of early childhood (RWEC) and asthma. Conversely, two randomized placebo-controlled trials of efficacious anti-RSV monoclonal antibodies (mAbs) in heterogenous infant populations found no difference in physician-diagnosed RWEC or asthma by treatment group. If a causal association exists and RSV vaccines and mAbs can prevent a substantial fraction of RWEC/asthma, the full public health value of these interventions would markedly increase. The primary alternative interpretation of the observational data is that RSV LRTI in early life is a marker of an underlying predisposition for the development of RWEC and asthma. If this is the case, RSV vaccines and mAbs would not necessarily be expected to impact these outcomes. To evaluate whether the available evidence supports a causal association between RSV LRTI and RWEC/asthma and to provide guidance for future studies, the World Health Organization convened a meeting of subject matter experts on February 12-13, 2019 in Geneva, Switzerland. After discussing relevant background information and reviewing the current epidemiologic evidence, the group determined that: (i) the evidence is inconclusive in establishing a causal association between RSV LRTI and RWEC/asthma, (ii) the evidence does not establish that RSV mAbs (and, by extension, future vaccines) will have a substantial effect on these outcomes and (iii) regardless of the association with long-term childhood respiratory morbidity, severe acute RSV disease in young children poses a substantial public health burden and should continue to be the primary consideration for policy-setting bodies deliberating on RSV vaccine and mAb recommendations. Nonetheless, the group recognized the public health importance of resolving this question and suggested good practice guidelines for future studies.

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.

Risk scoring tool to predict respiratory syncytial virus hospitalisation in premature infants

BACKGROUND

The objective was to develop a risk scoring tool which predicts respiratory syncytial virus hospitalisation (RSVH) in moderate-late preterm infants (32-35 weeks' gestational age) in the Northern Hemisphere.

METHODS

Risk factors for RSVH were pooled from six observational studies of infants born 32 weeks and 0 days to 35 weeks and 6 days without comorbidity from 2000 to 2014. Of 13 475 infants, 484 had RSVH in the first year of life. Logistic regression was used to identify the most predictive risk factors, based on area under the receiver operating characteristic curve (AUROC). The model was validated internally by 100-fold bootstrapping and externally with data from a seventh observational study. The model coefficients were converted into rounded multipliers, stratified into risk groups, and number needed to treat (NNT) calculated.

RESULTS

The risk factors identified in the model included (i) proximity of birth to the RSV season; (ii) second-hand smoke exposure; and (iii) siblings and/or daycare. The AUROC was 0.773 (sensitivity: 68.9%; specificity: 73.0%). The mean AUROC from internal bootstrapping was 0.773. For external validation with data from Ireland, the AUROC was 0.707 using Irish coefficients and 0.681 using source model coefficients. Cut-off scores for RSVH were ≤19 for low- (1.0%), 20-45 for moderate- (3.3%), and 50-56 (9.5%) for high-risk infants. The high-risk group captured 62.0% of RSVHs within 23.6% of the total population (NNT 15.3).

CONCLUSIONS

This risk scoring tool has good predictive accuracy and can improve targeting for RSVH prevention in moderate-late preterm infants.

Healthcare resource use and economic burden attributable to respiratory syncytial virus in the United States: a claims database analysis

Background

Despite several studies that have estimated the economic impact of Respiratory Syncytial Virus (RSV) in infants, limited data are available on healthcare resource use and costs attributable to RSV across age groups. The aim of this study was to quantify age-specific RSV-related healthcare resource use and costs on the US healthcare system.

Methods

This retrospective case-control study identified patients aged ≥1 year with an RSV event in the Truven Health Marketscan® Commercial Claims and Encounters and Medicare Supplemental and Coordination of Benefits databases between August 31, 2012 and August 1, 2013. RSV patients were matched 1:1 with non-RSV controls for age, gender, region, healthcare plan and index date (n = 11,432 in each group). Stratified analyses for healthcare resource use and costs were conducted by age groups. RSV-attributable resource use and costs were assessed based on the incremental differences between RSV cases and controls using multivariate analysis.

Results

RSV patients had a higher healthcare resource use (hospital stays, emergency room/urgent care visits, ambulatory visits and outpatient visits) than non-RSV matched controls for all age groups (all p < 0.0001), particularly in the elderly age groups with RSV (1.9 to 3 days length of stay, 0.4 to 0.5 more ER/UC visits, 0.7 to 2.7 more ambulatory visits, 12.1 to 18.6 more outpatient visits and 9.5 to 14.6 more prescriptions than elderly in the control groups). The incremental difference in adjusted mean annual costs between RSV and non-RSV controls was higher in elderly (≥65; $12,030 to $23,194) than in those aged < 65 years ($2251 to $5391). Among children, adjusted costs attributable to RSV were higher in children aged 5–17 years ($3192), than those 1–4 years ($2251 to $2521).

Conclusions

Our findings showed a substantial annual RSV-attributable healthcare resource use and costs in the US across age groups, with the highest burden in those aged ≥65 years. These data can be used in cost-effectiveness analyses, and may be useful for policymakers to guide future RSV vaccination and other prevention programs.

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.

Burden of Severe Respiratory Syncytial Virus Disease Among 33-35 Weeks' Gestational Age Infants Born During Multiple Respiratory Syncytial Virus Seasons

BACKGROUND

Moderate-late preterm infants, 33-35 weeks' gestational age (wGA), are at increased risk for respiratory syncytial virus hospitalization (RSVH). The objective of this study is to quantify the burden of RSVH in moderate-late preterm infants.

METHODS

A pooled analysis was conducted on RSVH from 7 prospective, observational studies in the Northern Hemisphere from 2000 to 2014. Infants' 33-35 wGA without comorbidity born during the respiratory syncytial virus season who did not receive respiratory syncytial virus immunoprophylaxis were enrolled. Data for the first confirmed RSVH during the season (+1 month) were analyzed. Incidence and hospitalization rate per 100 patient-seasons, intensive care unit admission and length of stay (LOS), oxygen support, mechanical ventilation and overall hospital LOS were assessed.

RESULTS

The pooled analysis comprised 7,820 infants; 267 experienced a confirmed RSVH at a median age of 8.4 weeks. The crude pooled RSVH incidence rate was 3.41% and the rate per 100 patient-seasons was 4.52. Median hospital LOS was 5.7 days. A total of 22.2% of infants required intensive care unit admission for a median LOS of 8.3 days. A total of 70.4% received supplemental oxygen support for a median of 4.9 days, and 12.7% required mechanical ventilation for a median of 4.8 days.

CONCLUSIONS

The burden of RSVH in moderate-late, 33-35 weeks' wGA preterm infants without comorbidities born during the viral season in Northern Hemisphere countries is substantial. Severe cases required prolonged and invasive supportive therapy.

Impact of hospitalizations for bronchiolitis in preterm infants on long-term health care costs in Italy: a retrospective case-control study

Purpose

Bronchiolitis is an acute inflammatory injury of the bronchioles, and is the most frequent cause of hospitalization for lower respiratory tract infections in preterm infants. This was a retrospective, observational, case-control study conducted in Italy, based on administrative database analysis. The aim of this study was to evaluate differences in health care costs of preterm infants with and without early hospitalization for bronchiolitis.

Patients and methods

Preterm infants born in the period between January 1, 2009 and December 31, 2010 and hospitalized for bronchiolitis in the first year of life were selected from the ARNO Observatory database and observed for the first 4 years of life. These preterm infants were compared (paired 1–3) with preterm infants who were not hospitalized for bronchiolitis in the first year of life and with similar characteristics. Only direct health care costs reimbursed by the Italian National Health Service were considered for this study (drugs, hospitalizations, and diagnostic/therapeutic procedures).

Results

Of 40,823 newborns in the accrual period, 863 were preterm with no evidence of prophylaxis, and 22 preterm infants were hospitalized for bronchiolitis (cases) and paired with 62 controls. Overall, cases had 74% higher average cost per infant in the first 4 years of life than controls (18,624€ versus 10,189€, respectively). The major cost drivers were hospitalizations, accounting for >90% in both the populations. The increase in total yearly health care cost between cases and controls remained substantial even in the fourth year of life for all cost items. A relevant increase in hospitalizations and drug consumption linked to respiratory tract diseases was noted in infants hospitalized for bronchiolitis during the entire follow-up period.

Conclusion

Preterm infants hospitalized for bronchiolitis in the first year of life were associated with increased resource consumption and costs throughout the entire period of observation; even in the fourth year, the difference versus paired controls was relevant.

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.

A population-based study of childhood respiratory morbidity after severe lower respiratory tract infections in early childhood

OBJECTIVES

To estimate the risk of childhood chronic respiratory morbidity among those hospitalized for severe lower respiratory tract infection (LRTI) in early childhood, and to determine whether severe LRTI is an independent predictor.

STUDY DESIGN

The population-based Régie de l'Assurance Maladie du Québec datasets were used to identify LRTI hospitalizations before age 2 years in a birth cohort from 1996-1997 and a comparison cohort of children without an LRTI hospitalization. The incidence rate and incidence rate ratio of chronic respiratory morbidity before age 10 years were calculated, and multivariable logistic regression was performed to estimate the impact of LRTI hospitalization on chronic respiratory morbidity. Population-attributable risks of chronic respiratory morbidity due to severe LRTI were estimated, and similar analyses were performed for respiratory syncytial virus LRTI.

RESULTS

Among the birth cohort, 7104 patients (4.9%) were hospitalized for LRTI before age 2 years. By age 10 years, 52.5% of the LRTI cohort and 27.9% of the nonhospitalized cohort had developed chronic respiratory morbidity; the incidence rate ratio was 1.81 (95% CI, 1.76-1.86) for males and 1.91 (95% CI, 1.84-1.99) for females. The OR for chronic respiratory morbidity based on LRTI hospitalization before age 2 years was 2.79 (95% CI, 2.66-2.93). The population-attributable risk of chronic respiratory morbidity due to any LRTI was approximately 25%, and that for respiratory syncytial virus LRTI was similar.

CONCLUSIONS

Hospitalization of young children for LRTIs is associated with two-fold increased risk of childhood chronic respiratory morbidity, demonstrating the ongoing impact of LRTI in infancy.

Association between respiratory syncytial virus hospitalizations in infants and respiratory sequelae: systematic review and meta-analysis

BACKGROUND

The association between hospitalization for respiratory syncytial virus (RSV) infection in infancy and asthma/wheezing in later life has long been studied. However, no published studies have combined systematic review and meta-analysis of existing evidence.

PURPOSE

To quantify the link between RSV hospitalization in early life and subsequent diagnosis of asthma.

METHOD

A systematic search was conducted using MEDLINE and EMBASE databases. Studies were selected for meta-analysis if they assessed the association between RSV-confirmed hospitalization for up to 3 years of age and asthma/wheezing later in life. Potential sources of heterogeneity were identified by stratified analysis.

RESULTS

Twenty articles representing 15 unique studies of 82,008 unique individuals (including 1533 with RSV-confirmed hospitalization) were selected for meta-analysis. Children who had RSV disease in early life had a higher incidence of asthma/wheezing in later life (odds ratio: 3.84; 95% confidence interval: 3.23-4.58). There was moderate heterogeneity between studies (I² = 45%). The association was found to decrease with age at follow-up, consistent with the findings of longitudinal studies. When age at follow-up was considered, heterogeneity was low (residual I² = 17%).

LIMITATIONS

Study quality was generally poor because randomization to hospitalization for RSV infection was not possible, appropriate blinding was rare and adjustment for confounding variables was not always appropriate.

CONCLUSIONS

The meta-analysis suggests an association between infant RSV hospitalization and respiratory morbidity that decreases with age. If the association is causal, the development of an effective vaccine against RSV could decrease the burden of asthma.

Association of RSV-related hospitalization and non-compliance with palivizumab among commercially insured infants: a retrospective claims analysis

BACKGROUND

Palivizumab has been shown to decrease the incidence of hospitalization due to respiratory syncytial virus (RSV) in infants at risk of severe RSV disease. We examined the association between compliance with palivizumab dosing throughout the RSV season and risk of RSV-related hospitalization in clinical practice.

METHODS

Subjects who were born and discharged from the hospital before the RSV season and received ≥1 palivizumab dose during their first RSV season were identified from a large US commercial health insurance database between 01/01/03 and 12/31/09. Subjects were deemed compliant if they received ≥5 palivizumab doses without gaps (>35 days) and their first dose was received by November 30. RSV-related hospitalizations were identified using ICD-9-CM diagnosis codes and examined over 2 observation periods: post-index dose and RSV season. A Cox proportional hazard model was used to evaluate the association between non-compliance and RSV-related hospitalization.

RESULTS

Of the 5,003 subjects who received palivizumab, 62% were deemed non-compliant. Non-compliant subjects had significantly higher unadjusted rates of RSV-related hospitalizations compared to compliant subjects during both observation periods (post-index: 6.1 vs. 2.8 per 100 infant seasons, p < 0.001; RSV season: 5.9% vs. 2.3%; p < 0.001). In multivariate analyses, non-compliance was significantly associated with higher risk of RSV-related hospitalization (HR = 2.01; p < 0.001). Of the 225 RSV-related hospitalizations observed during the RSV season, 61 (27%) occurred before the first dose of palivizumab.

CONCLUSIONS

Subjects who did not receive monthly dosing of palivizumab throughout the RSV season had significantly higher rates of RSV-related hospitalizations. The RSV-related hospitalizations prior to the first dose of palivizumab suggest some dosing was started too late.

Viral respiratory burden in moderate-to-late preterm infants

More than 1 in 10 babies are born prematurely and most of them are born after gestational age 32 weeks. Mortality and morbidity are more common in these moderate-to-late preterm infants than in full-term children. In this review, mechanisms and epidemiology of long-term airway morbidity in moderate-to-late preterm infants will be discussed. We discuss the potential of viral respiratory infections to further aggravate abnormal lung function associated with preterm birth.

Respiratory distress syndrome at birth is a risk factor for hospitalization for lower respiratory tract infections in infancy

BACKGROUND

Respiratory distress syndrome (RDS) and hospitalization for lower respiratory tract infection (LRTI; specifically, respiratory syncytial virus) are important causes of morbidity in infancy. Whether RDS at birth is an independent risk factor for LRTI is unknown. This study estimated the risk of LRTI-related hospitalization among late preterm infants with a history of RDS.

METHODS

The population-based cohort from Québec included all late preterm infants (32-36 weeks gestational age) born in 1996 to 1997. RDS was identified by International Classification of Diseases, Ninth Revision code 769, and a comparison cohort generated from all without RDS. A multivariable model estimated the adjusted odds ratio of LRTI-related hospitalization among late preterm infants with a history of RDS; and the incidence and increased risk of childhood chronic respiratory morbidity was calculated.

RESULTS

Of the 7488 late preterms, 459 (6.1%) had a history of RDS; 525 late preterms (7.0%) were hospitalized for LRTI in infancy, including 57 (12.4%) with RDS. The adjusted odds ratio for LRTI-related hospitalization associated with RDS was 1.6 (1.2-2.2). Other significant risk factors included male sex, or diagnosis of other respiratory conditions, diaphragm anomalies, bacteremia, intraventricular hemorrhage, congenital heart disease or respiratory system anomalies. Late preterm infants with a history of RDS were also at a significantly increased risk of childhood chronic respiratory morbidity.

CONCLUSIONS

Late preterms with a history of RDS are at a 60% increased risk of LRTI-related hospitalization in infancy compared with late preterm infants without RDS. Such infants may benefit from interventions decreasing the risk of contracting respiratory viruses causing acute LRTI.

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.