Multicenter study of viral etiology and relapse in hospitalized children with bronchiolitis

Impact of RSV test positivity, patient characteristics, and treatment characteristics on the cost of hospitalization for acute bronchiolitis in a French university medical center (2010-2015)

Background

In young children, respiratory syncytial virus (RSV)-related bronchiolitis is typically more severe than other respiratory tract infections, with a greater need for oxygen therapy and respiratory support. Few studies have compared the cost of hospitalization with regard to virological status. The objective of this study was to compare the costs of hospitalization for RSV-positive vs. RSV-negative bronchiolitis in a French university medical center between 2010 and 2015.

Methods

The cost models were compared using conventional goodness-of-fit criteria. Covariates included the characteristics of the patients, pre-existing respiratory and non-respiratory comorbidities, superinfections, medical care provided, and the length of stay.

Results

RSV was detected in 679 (58.3%) of the 1,164 hospital stays by children under 2 years with virological data. Oxygen therapy and respiratory support were twice as frequent for the RSV-positive cases. The median hospitalization cost was estimated at €3,248.4 (interquartile range: €2,572.1). The cost distribution was positively skewed with a variation coefficient (CV = standard deviation/mean) greater than one (mean = €4,212.9, standard deviation = €5,047, CV = 1.2). In univariate analyses, there was no significant cost difference between the RSV-positive and RSV-negative cases. In the best multivariate model, the significant positive effect of RSV positivity on cost waned after the introduction of medical care variables and the length of stay. The results were sensitive to the specification of the model.

Conclusions

It was impossible to firmly conclude that hospitalization costs were higher for the RSV-positive cases.

Factors associated with mild bronchiolitis in young infants

Objective

Bronchiolitis within the first 3 months of life is a risk factor for more severe illness. We aimed to identify characteristics associated with mild bronchiolitis in infants ≤90 days old presenting to the emergency department (ED).

Methods

We conducted a secondary analysis of infants ≤90 days old with clinically diagnosed bronchiolitis using data from the 25th Multicenter Airway Research Collaboration prospective cohort study. We excluded infants with direct intensive care unit admissions. Mild bronchiolitis was defined as (1) sent home after the index ED visit and did not have a return ED visit or had a return ED visit without hospitalization, or (2) were hospitalized from the index ED visit to the inpatient floor for <24 hours. Multivariable logistic regression, adjusting for potential clustering by hospital site, was used to identify factors associated with mild bronchiolitis.

Results

Of 373 infants aged ≤90 days, 333 were eligible for analysis. Of these, 155 (47%) infants had mild bronchiolitis, and none required mechanical ventilation. Adjusting for infant characteristics, clinical factors associated with mild bronchiolitis included older age (61-90 days vs 0-60 days) (odds ratio [OR] 2.72, 95% confidence interval [CI] 1.52-4.87), adequate oral intake (OR 4.48, 95% CI 2.08-9.66), and lowest ED oxygen saturation ≥94% (OR 3.12, 95% CI 1.55-6.30).

Conclusions

Among infants aged ≤90 days presenting to the ED with bronchiolitis, about half had mild bronchiolitis. Mild illness was associated with older age (61-90 days), adequate oral intake, and oxygen saturation ≥94%. These predictors may help in the development of strategies to limit unnecessary hospitalization in young infants with bronchiolitis.

Clinical characteristics and differential cytokine expression in hospitalized Taiwanese children with respiratory syncytial virus and rhinovirus bronchiolitis

BACKGROUND

Viral bronchiolitis presents a heterogeneous spectrum. In this study, we investigated the clinical characteristics and the cytokines/chemokines profiles among respiratory syncytial virus (RSV), rhinovirus (RV), and their dual infection in Taiwanese children with viral bronchiolitis.

METHOD

This study was conducted between October 2014 and June 2017. Viral etiology was identified using a Luminex respiratory virus panel and blood cytokines were evaluated using a MILLIPLEX MAP Human Cytokine/Chemokine Panel. Cytokine/Chemokine expressions were compared by clinical severity, steroid treatment, and viral entities.

RESULTS

A total of 184 patients were evaluated; at least one respiratory virus was identified in 163 (88.6%) patients. RSV and RV were the two leading viral etiologies, with 25.5% and 17.3%, respectively. RV bronchiolitis has a comparable severity to RSV but is more common in children of an older age with a history of recurrent wheezing and blood eosinophilia. Decreased tumor necrosis factor-alpha (TNF-α) and interferon gamma (INF-γ) levels were correlated with clinical severity. Patients infected with RV exhibited higher levels of Interleukin (IL)-22, IL-23, IL-25, IL-31, and IL-33 (p < 0.05), whereas those with RSV had higher levels of TNF-α, INF-γ, and IL-10 (p < 0.05). Systemic steroid treatment was associated with higher expressions of IL-4, IL-8, IL-13, and MIP-1α levels (p < 0.05). Cluster analysis revealed a high correlation of IL-33 and IL-31(R² = 0.9731, p < 0.0001).

CONCLUSION

Different viral infections elicited the characteristic clinical presentation and immune profiles in bronchiolitis. Our findings also highlight the role of the IL-33/IL-31 axis in the immunopathogenesis of bronchiolitis.

Realising respiratory microbiomic meta-analyses: time for a standardised framework

In microbiome fields of study, meta-analyses have proven to be a valuable tool for identifying the technical drivers of variation among studies and results of investigations in several diseases, such as those of the gut and sinuses. Meta-analyses also represent a powerful and efficient approach to leverage existing scientific data to both reaffirm existing findings and generate new hypotheses within the field. However, there are currently limited data in other fields, such as the paediatric respiratory tract, where extension of original data becomes even more critical due to samples often being difficult to obtain and process for a range of both technical and ethical reasons. Performing such analyses in an evolving field comes with challenges related to data accessibility and heterogeneity. This is particularly the case in paediatric respiratory microbiomics - a field in which best microbiome-related practices are not yet firmly established, clinical heterogeneity abounds and ethical challenges can complicate sharing of patient data. Having recently conducted a large-scale, individual participant data meta-analysis of the paediatric respiratory microbiota (n = 2624 children from 20 studies), we discuss here some of the unique barriers facing these studies and open and invite a dialogue towards future opportunities. Video Abstract.

The Differences Between RSV and no RSV Acute Bronchiolitis in Hospitalized Infants: A Cross-Sectional Study

To identify the differences between the RSV and non-RSV bronchiolitis in hospitalized infants in a Greek tertiary pediatric unit and the possible risk factors related to severe forms of the illness. We performed a retrospective cross-sectional data analysis by reviewing medical records of patients that were hospitalized for acute bronchiolitis from 2012 to 2019. The patients with RSV bronchiolitis were found to require antibiotic treatment, IV fluids, adrenaline, and hypertonic saline inhalations more frequently than the non-RSV patients. They also required prolonged hospitalization, especially those that were admitted to PICU, and received oxygen therapy for longer periods. We searched risk factors for severe forms of the disease according to the need for admission to PICU, the supplemental oxygen and the extended length of hospital stay, concurrently. The patients with RSV bronchiolitis developed more severe illness in comparison with patients with bronchiolitis due to other respiratory viruses.

Variations in the pathophysiology of respiratory syncytial virus infection depend on the age at onset

BACKGROUND

Lower respiratory tract infections due to respiratory syncytial virus are associated with morbidity and mortality in infants and children. Thus precise elucidation of respiratory syncytial virus lower respiratory tract infection pathophysiology is important.

METHODS

Medical records of hospitalized patients were reviewed. Patients were divided into three groups. Group I: patients who improved without oxygen supply. Group II: patients who received oxygen supply, but not nasal high-flow cannula therapy. Group III: patients who received nasal high-flow cannula. Patients were also divided by age group into the <6 months and ≥6 months groups. Parameters for differentiating the severity among groups were then evaluated. Further, serum concentration of high-mobility group box-1 and several cytokines (Inerleukin-6, soluble tumor necrosis factor receptor-1/2, Interleukin-18, Interferon-gamma responsive protein-100) were evaluated.

RESULTS

One hundred eighty-nine were enrolled. An analysis of variance for those <6 months showed overall differences including younger age, lower pH, and increased partial pressure of carbon dioxide (pCO2), bicarbonate (HCO3-), and base excess at the time of admission. On the other hand, analysis of variance for ≥6 months revealed that, in addition to a lower pH and increased pCO2, patients showed differences including decreased serum total protein and albumin, and increased aspartate aminotransferase (AST), alanin aminotransferase (ALT), lactate dehydrogenase (LDH), Ferritin and C-reactive protein (CRP) levels. Further, evaluation of serum cytokines showed that IL-6, s tumor necrotizing factor receptor-1/2, and high-mobility group box-1 were higher in Group II/III among the ≥6 months age group, but not for those in the <6 months group.

CONCLUSIONS

The pathophysiology of severe respiratory syncytial virus lower respiratory tract infection varies according to the age at onset. In late infancy and childhood, a certain proportion of patients show a hyperinflammatory status.

Clinico-virological Profile, Intensive Care Needs, and Outcome of Infants with Acute Viral Bronchiolitis: A Prospective Observational Study

OBJECTIVES

The objective of the study was to describe the clinico-virological profile, treatment details, intensive care needs, and outcome of infants with acute viral bronchiolitis (AVB).

METHODOLOGY

In this prospective observational study, 173 infants with AVB admitted to the pediatric emergency room and pediatric intensive care unit (PICU) of a tertiary care teaching hospital in North India during November 2019 to February 2020 were enrolled. The data collection included clinical features, viruses detected [respiratory syncytial virus (RSV), rhinovirus, influenza A virus, parainfluenza virus (PIV) 2 and 3, and human metapneumovirus (hMPV)], complications, intensive care needs, treatment, and outcomes. Multivariate analysis was performed to determine independent predictors for PICU admission.

RESULTS

Most common symptoms were rapid breathing (98.8%), cough (98.3%), and fever (74%). On examination, tachypnea (98.8%), chest retractions (93.6%), respiratory failure (84.4%), wheezing (49.7%), and crepitations (23.1%) were observed. RSV and rhinovirus were the predominant isolates. Complications were noted in 25% of cases as encephalopathy (17.3%), transaminitis (14.3%), shock (13.9%), acute kidney injury (AKI) (7.5%), myocarditis (6.4%), multiple organ dysfunction syndrome (MODS) (5.8%), and acute respiratory distress syndrome (ARDS) (4.6%). More than one-third of cases required PICU admission. The treatment details included nasal cannula oxygen (11%), continuous positive airway pressure (51.4%), high-flow nasal cannula (14.5%), mechanical ventilation (23.1%), nebulization (74%), antibiotics (35.9%), and vasoactive drugs (13.9%). The mortality was 8.1%. Underlying comorbidity, chest retractions, respiratory failure at admission, presence of shock, and need for mechanical ventilation were independent predictors of PICU admission. Isolation of virus or coinfection was not associated with disease severity, intensive care needs, and outcomes.

CONCLUSION

Among infants with AVB, RSV and rhinovirus were predominant. One-third infants with AVB needed PICU admission. The presence of comorbidity, chest retractions, respiratory failure, shock, and need for mechanical ventilation independently predicted PICU admission.

HOW TO CITE THIS ARTICLE

Angurana SK, Takia L, Sarkar S, Jangra I, Bora I, Ratho RK, et al. Clinico-virological Profile, Intensive Care Needs, and Outcome of Infants with Acute Viral Bronchiolitis: A Prospective Observational Study. Indian J Crit Care Med 2021;25(11):1301-1307.

Epidemiology of Bronchiolitis in Hospitalized Infants at Tawam Hospital, Al Ain, United Arab Emirates

Background

Bronchiolitis is the commonest lower respiratory tract infection, found worldwide in children < 2 years of age. Over sixty percent of cases are caused by Respiratory Syncytial Virus (RSV). The disease is known to have significant morbidity, mortality and health care costs. Its seasonal variability, manifestations and complications vary between countries. The aim of this study was to determine the epidemiological and clinical characteristics of infants hospitalized with bronchiolitis in Al Ain City, United Arab Emirates.

Methods

Retrospective observational chart review was made of an unselected cohort of infants ≤ 2 years admitted to the pediatric department of Tawam hospital over a 3-year period and discharged with the diagnosis of bronchiolitis. Epidemiological data and risk factors were analyzed.

Results

RSV was the commonest pathogen (51%). Hospitalizations occurred year-round but increased significantly in December and January. The patients' median age was 5.8 months with a male predominance (male:female ratio of 1.5:1.0). The mean age at admission was 6.6 months and presentation occurred, on average, 2.9 days after the onset of the symptoms. The majority (94%) had respiratory distress on presentation. Chest x-ray was performed in 80% of the patients. Most children received bronchodilator therapy and oxygen therapy was administered to 42%. The mean duration of hospital stay was 3 days.

Conclusion

Bronchiolitis remains a common reason for hospital admission and carries significant morbidity. RSV is the primarily responsible virus for hospital admissions and morbidity.A better understanding of the burden of bronchiolitis in our setting would enable better planning and use of hospital resources to minimize its short and long-term sequelae.

Risk of Repeated Admissions for Respiratory Syncytial Virus in a Cohort of >10 000 Hospitalized Children

BACKGROUND

The objective was to describe respiratory syncytial virus (RSV) hospitalizations in Alberta, Canada over a 13-year period with an emphasis on the incidence and risk factors for repeat hospitalizations attributable to new RSV infections.

METHODS

This was a retrospective database analysis. The Alberta Health Services Discharge Abstract Database was searched for patients <5 years of age admitted to any hospital with a primary diagnosis of RSV from July 1, 2004 through June 30, 2017. Clinical characteristics were compared for children with repeat RSV admission during the same RSV season (but >30 days apart so presumably due to separate infections) compared with all other children with RSV admissions.

RESULTS

During the study period, 10 212 children had 10 967 RSV admissions. The RSV hospitalization rate was 1.6%. A total of 666 children (6.5%) were readmitted for RSV at least once during the study period, of whom 433 (4.2%) were readmitted within 30 days of the initial hospital discharge. There were 36 children (0.35%) with 2 RSV admissions >30 days apart during the same RSV season. When compared to all other children with RSV admissions, they were more likely to have congenital heart disease or to have been diagnosed with RSV pneumonia (vs bronchiolitis or upper respiratory tract infection) during their initial hospitalization.

CONCLUSIONS

The RSV hospitalization rate in children <5 years of age was 1.6%. Repeat RSV infections requiring readmission during the same RSV season occurred following only 0.35% of RSV hospitalizations.

Magnesium sulphate for treating acute bronchiolitis in children up to two years of age

BACKGROUND

Acute bronchiolitis is a significant burden on children, their families and healthcare facilities. It mostly affects children younger than two years of age. Treatment involves adequate hydration, humidified oxygen supplementation, and nebulisation of medications, such as salbutamol, epinephrine, and hypertonic saline. The effectiveness of magnesium sulphate for acute bronchiolitis is unclear.

OBJECTIVES

To assess the effects of magnesium sulphate in acute bronchiolitis in children up to two years of age.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, CINAHL, and two trials registries to 30 April 2020. We contacted trial authors to identify additional studies. We searched conference proceedings and reference lists of retrieved articles. Unpublished and published studies were eligible for inclusion.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs, comparing magnesium sulphate, alone or with another treatment, with placebo or another treatment, in children up to two years old with acute bronchiolitis. Primary outcomes were time to recovery, mortality, and adverse events. Secondary outcomes were duration of hospital stay, clinical severity score at 0 to 24 hours and 25 to 48 hours after treatment, pulmonary function test, hospital readmission within 30 days, duration of mechanical ventilation, and duration of intensive care unit stay.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We used GRADE methods to assess the certainty of the evidence.

MAIN RESULTS

We included four RCTs (564 children). One study received funding from a hospital and one from a university; two studies did not report funding sources. Comparator interventions differed among all four trials. Studies were conducted in Qatar, Turkey, Iran, and India. We assessed two studies to be at an overall low risk of bias, and two to be at unclear risk of bias, overall. The certainty of the evidence for all outcomes and comparisons was very low except for one: hospital re-admission rate within 30 days of discharge for magnesium sulphate versus placebo. None of the studies measured time to recovery, duration of mechanical ventilation, duration of intensive care unit stay, or pulmonary function. There were no events of mortality or adverse effects for magnesium sulphate compared with placebo (1 RCT, 160 children). The effects of magnesium sulphate on clinical severity are uncertain (at 0 to 24 hours: mean difference (MD) on the Wang score 0.13, 95% confidence interval (CI) -0.28 to 0.54; and at 25 to 48 hours: MD on the Wang score -0.42, 95% CI -0.84 to -0.00). Magnesium sulphate may increase hospital re-admission rate within 30 days of discharge (risk ratio (RR) 3.16, 95% CI 1.20 to 8.27; 158 children; low-certainty evidence). None of our primary outcomes were measured for magnesium sulphate compared with hypertonic saline (1 RCT, 220 children). Effects were uncertain on the duration of hospital stay in days (MD 0.00, 95% CI -0.28 to 0.28), and on clinical severity on the Respiratory Distress Assessment Instrument (RDAI) score at 25 to 48 hours (MD 0.10, 95% CI -0.39 to 0.59). There were no events of mortality or adverse effects for magnesium sulphate, with or without salbutamol, compared with salbutamol (1 RCT, 57 children). Effects on the duration of hospital stay were uncertain (magnesium sulphate: 24 hours (95% CI 25.8 to 47.4), magnesium sulphate + salbutamol: 20 hours (95% CI 15.3 to 39.0), and salbutamol: 24 hours (95% CI 23.4 to 76.9)). None of our primary outcomes were measured for magnesium sulphate + epinephrine compared with no treatment or normal saline + epinephrine (1 RCT,120 children). Effects were uncertain for the duration of hospital stay in hours (MD -0.40, 95% CI -3.94 to 3.14), and for RDAI scores (0 to 24 hours: MD -0.20, 95% CI -1.06 to 0.66; and 25 to 48 hours: MD -0.90, 95% CI -1.75 to -0.05).

AUTHORS' CONCLUSIONS

There is insufficient evidence to establish the efficacy and safety of magnesium sulphate for treating children up to two years of age with acute bronchiolitis. No evidence was available for time to recovery, duration of mechanical ventilation and intensive care unit stay, or pulmonary function. There was no information about adverse events for some comparisons. Well-designed RCTs to assess the effects of magnesium sulphate for children with acute bronchiolitis are needed. Important outcomes, such as time to recovery and adverse events should be measured.

Innate IFN-lambda responses to dsRNA in the human infant airway epithelium and clinical regulatory factors during viral respiratory infections in early life

INTRODUCTION

IFN lambda (type III-IFN-λ1) is a molecule primarily produced by epithelial cells that provides an important first-line defence against viral respiratory infections and has been linked to the pathogenesis of viral-induced wheezing in early life. The goal of this study was to better understand the regulation of innate IFN-lambda responses in vitro in primary human infant airway epithelial cells (AECs) and in vivo using nasal aspirates during viral respiratory infections.

METHODS

IFN-lambda protein levels were quantified: (a) in human infant AECs exposed to (poly(I:C) dsRNA) under different experimental conditions (n = 8 donors); and (b) in nasal aspirates of young children (≤3 years) hospitalized with viral respiratory infection (n = 138) and in uninfected controls (n = 74). In vivo IFN-lambda airway levels during viral infections were correlated with individual characteristics and respiratory disease parameters.

RESULTS

Our in vitro experiments showed that the poly(I:C)-induced innate production of IFN lambda in human infant AECs is regulated by (a) p38-MAPK/NF-kB dependent mechanism; and (b) exposure to pro-inflammatory signals such as IL1β. Our in vivo studies demonstrated that (a) infants (<18 months) had higher virus-induced IFN-lambda airway secretion; (b) subjects with RSV infection showed the highest IFN-lambda airway levels; and (c) individuals with the highest virus-induced IFN-lambda levels (>90th percentile) had higher viral loads and were more likely to have respiratory sick visits within 12 months of discharge (OR = 5.8).

CONCLUSION

IFN-lambda responses to dsRNA in the human infant airway epithelium are regulated by p38-MAPK and NF-kB signalling. High in vivo IFN-lambda production is influenced by virus type and associated with recurrent respiratory sick visits in young children.

Phenotypical Sub-setting of the First Episode of Severe Viral Respiratory Infection Based on Clinical Assessment and Underlying Airway Disease: A Pilot Study

Introduction: Viral bronchiolitis is a term often used to group all infants with the first episode of severe viral respiratory infection. However, this term encompasses a collection of different clinical and biological processes. We hypothesized that the first episode of severe viral respiratory infection in infants can be subset into clinical phenotypes with distinct outcomes and underlying airway disease patterns. Methods: We included children (≤2 years old) hospitalized for the first time due to PCR-confirmed viral respiratory infection. All cases were categorized based on primary manifestations (wheezing, sub-costal retractions and hypoxemia) into mild, hypoxemia or wheezing phenotypes. We characterized these phenotypes using lung-X-rays, respiratory outcomes and nasal protein levels of antiviral and type 2 cytokines (IFNγ, IL-10, IL-4, IL-13, IL-1β, and TNFα). Results: A total of 50 young children comprising viral respiratory infection cases (n = 41) and uninfected controls (n = 9) were included. We found that 22% of viral respiratory infection cases were classified as mild (n = 9), 39% as hypoxemia phenotype (n = 16) and 39% as wheezing phenotype (n = 16). Individuals in the hypoxemia phenotype had more lung opacities, higher probability of PICU admission and prolonged hospitalizations. Subjects in the wheezing phenotype had higher probability of recurrent sick visits. Nasal cytokine profiles showed that individuals with recurrent sick visits in the wheezing phenotype had increased nasal airway levels of type 2 cytokines (IL-13/IL-4). Conclusion: Clinically-based classification of the first episode of severe viral respiratory infection into mild, hypoxemia or wheezing phenotypes provides critical information about respiratory outcomes, lung disease patterns and underlying airway immunobiology.

Bedside clinical assessment predicts recurrence after hospitalization due to viral lower respiratory tract infection in young children

Infants requiring hospitalization due to a viral lower respiratory tract infection (LRTI) have a high risk of developing recurrent respiratory illnesses in early life and asthma beyond childhood. Notably, all validated clinical scales for viral LRTI have focused on predicting acute severity instead of recurrence. We present a novel clinical approach combining individual risk factors with bedside clinical parameters to predict recurrence after viral LRTI hospitalization in young children. A retrospective longitudinal cohort of young children (≤3 years) designed to define clinical predictive factors of recurrent respiratory illnesses within 12 months after hospitalization due to PCR-confirmed viral LRTI. Data collection was through electronic medical record. We included 138 children hospitalized with viral LRTI. Using automatic stepwise logistic model selection, we found that the strongest predictors of recurrence in infants hospitalized for the first time were severe prematurity (≤32 weeks' gestational age, OR=5.19; 95% CI 1.76 to 15.32; p=0.002) and a clinical score that weighted hypoxemia, subcostal retractions and wheezing (OR=3.33; 95% CI 1.59 to 6.98; p<0.001). After the first hospitalization, the strongest predictors of subsequent episodes were wheezing (OR=5.62; 95% CI 1.03 to 30.62; p=0.04) and family history of asthma (OR=5.39; 95% CI 1.04 to 27.96; p=0.04). We found that integrating individual risk factors (eg, prematurity or family history of asthma) with bedside clinical assessment (eg, wheezing, subcostal retractions or hypoxemia) can predict the risk of recurrence after viral LRTI hospitalization in infants. This strategy may enable clinically oriented subsetting of infants with viral LRTI based on individual predictors for recurrent respiratory illnesses during early life.

Nasal Cytokine Profiles of Patients Hospitalised with Respiratory Wheeze Associated with Rhinovirus C

Background: Rhinovirus C is an important pathogen of asthmatic and non-asthmatic children hospitalised with episodic wheeze. Previous studies on other respiratory viruses have shown that several host cytokines correlate with duration of hospitalisation, but this has yet to be investigated in children with RV-C infection. We determined the nasal cytokine profiles of these children and investigated their relationship with RV-C load and clinical outcome. Flocked nasal swabs were collected from children aged 24–72 months presenting to the Emergency Department at Princess Margaret Hospital with a clinical diagnosis of acute wheeze and an acute upper respiratory tract viral infection. RV-C load was determined by quantitative RT-PCR and cytokine profiles were characterised by a commercial human cytokine 34-plex panel. RV-C was the most commonly detected virus in pre-school-aged children hospitalised with an episodic wheeze. RV-C load did not significantly differ between asthmatic and non-asthmatic patients. Both groups showed a Th2-based cytokine profile. However, Th17 response cytokines IL-17 and IL-1β were only elevated in RV-C-infected children with pre-existing asthma. Neither RV-C load nor any specific cytokines were associated illness severity in this study. Medically attended RV-C-induced wheeze is characterised by a Th2 inflammatory pattern, independent of viral load. Any therapeutic interventions should be aimed at modulating the host response following infection.

Bronchiolitis Admissions in a Lebanese Tertiary Medical Center: A 10 Years' Experience

Bronchiolitis and more specifically respiratory syncytial virus (RSV) bronchiolitis is a leading cause of global childhood morbidity and mortality. Despite the previous identification of possible risk factors associated with the severity of bronchiolitis, the data from Lebanon remains limited. We described the burden of bronchiolitis hospitalizations in children under 5 years of age in a tertiary care center in Lebanon from October 2004 to October 2014 and identified the risk factors associated with severe bronchiolitis. This was a retrospective cohort study conducted at the American University of Beirut Medical Center. Records of children younger than 5 years of age admitted with a diagnosis of bronchiolitis were reviewed. More than half the patients were RSV positive. RSV bronchiolitis was found to be significantly associated with longer hospital stay compared to children with non-RSV bronchiolitis (P = 0.007). Children exposed to smoking had an increased risk for longer hospital stay (P = 0.002) and were more likely to require ICU admission (P < 0.001) and supplemental oxygen (P = 0.045). Congenital heart disease was found to be a significant risk factor for severe bronchiolitis (P < 0.005). Conclusion: Patients with RSV bronchiolitis had a longer hospital stay compared to patients with non-RSV bronchiolitis. Exposure to smoking was associated with a more severe and complicated RSV infection. Congenital heart disease was the only risk factor significantly associated with all markers of bronchiolitis disease severity.

A fatal case of enterovirus infection with secondary hemophagocytosis-case report with review of literature

Enterovirus is a common viral infection, which can affect multiple organ systems with an array of clinical presentation such as meningitis, encephalitis, myocarditis, and disseminated infections. The illness is usually asymptomatic and self-limited but few cases can be severe and life-threatening especially when associated with hemophagocytosis. We discuss a fatal case of disseminated enterovirus infection and the histomorphological features of the infection.

Risk factors for bronchiolitis severity: A retrospective review of patients admitted to the university hospital from central region of Slovenia

Aim

Study's objective was to identify risk factors associated with bronchiolitis severity.

Methods

A retrospective chart review of all children <2 years old diagnosed with bronchiolitis at the University Medical Centre Ljubljana between May 2014 and April 2015, who were treated as outpatients (paediatric emergency department, PED group) or as inpatients in the standard hospital setting (WARD group) or in the paediatric intensive care unit (PICU group). Detection of respiratory viruses in nasopharyngeal swab was accomplished by RT‐PCR. Severity was assessed by Wang Respiratory Score and hospitalization longer than 24 hours.

Results

The study included 761 children. The three most frequently detected viruses were respiratory syncytial virus (RSV), human rhinovirus (hRV) and human bocavirus (hBoV) (57.5%, 272/473; 25.6%, 121/473; 18.4%, 87/473). Patient groups differed in Wang Respiratory Score for the severity of bronchiolitis (P < 0.001). No differences regarding the causative viruses were found. There was a lower proportion of children with the presence of more than one virus in PICU group compared to other two groups (P = 0.017). The three groups significantly differed in age, birthweight, comorbidities, bronchodilator treatment and antibiotic usage. However, multiple regression analysis revealed that younger age and the use of antibiotics were associated with bronchiolitis severity defined as hospitalization for >24 hours.

Conclusions

Respiratory syncytial virus, hRV and hBoV were the most frequently detected viruses. The majority of patients admitted to the PICU had only one virus detected. Younger age and the use of antibiotics were associated with bronchiolitis severity.

Relapse Among Infants Hospitalized for Bronchiolitis in Finland

In a prospective cohort of children hospitalized for bronchiolitis, we examined the rate of and characteristics associated with bronchiolitis relapse. Bronchiolitis relapse was documented in 22 (6%) of 391 children, and median time to relapse was 2 (interquartile range, 1-7) days. Relapse occurred more often in males. Prenatal smoking and smoke exposure in the home were also associated with relapse.

Intravenous Ribavirin for Parainfluenza and Respiratory Syncytial Virus in an Infant Receiving Extracorporeal Membrane Oxygenation and Continuous Renal Replacement Therapy

BACKGROUND Viral bronchiolitis remains a significant cause of hospitalization as well as morbidity and mortality during the first year of life, with treatment options beyond supportive care being limited. In cases of severe illness, ribavirin may offer therapeutic benefit.

OBJECTIVE We report the use of intravenous (IV) ribavirin in an infant requiring concomitant venovenous extracorporeal membrane oxygenation (VV-ECMO) and continuous venovenous hemofiltration (CVVH) for respiratory syncytial virus (RSV) and parainfluenza virus (PIV) coinfection.

PATIENTS AND METHODS A 5-week-old male former 33-week preterm infant was admitted with respiratory failure and subsequently tested positive for RSV and PIV-type 1 infection. Progressive clinical deterioration subsequently required the initiation of both VV-ECMO and CVVH. Although the patient received combined VV-ECMO and CVVH, IV ribavirin was administered, and serial plasma and ultrafiltrate samples were obtained for pharmacokinetic analyses after the first dose (collection period 1) and again after an estimated 5 half-lives (collection period 2).

RESULTS Pharmacokinetics for collection period 1 demonstrated a calculated Cmax of 11.99 mg/L, an AUC0–24 of 43.32 mg·hr/L, ke 0.26 hr−1, t½ 2.69 hr, Vd 10.04 L (2.92 L/kg, using patient's dosing weight 3.43 kg), CLT 43.47 mL/min, and CLCVVH 6.75 mL/min. Pharmacokinetics for collection period 2 demonstrated a calculated Cmax of 10.31 mg/L, AUC0–6 of 52.55 mg· hr/L, ke 0.06 hr−1, t½ 10.69 hr, Vd 17.5 L (5.1 L/kg), and CLT 17.44 mL/min. The sieving coefficient during collection period 1 was 1.17 (range, 1.07–1.37). The percent decline between prefilter and postfilter oxygenator was 19.1%.

CONCLUSION Our patient demonstrated therapeutic concentrations of ribavirin, despite drug removal via CVVH and the ECMO oxygenator. Standard ribavirin dosing used and resultant concentrations achieved were associated with viral clearance and clinical improvement.

Determining the outcomes of interventions to prevent respiratory syncytial virus disease in children: what to measure?

Respiratory syncytial virus (RSV) is the most common cause of viral acute lower respiratory tract illness (LRTI) in young children, and a major cause of hospital admissions and health-care utilisation globally. Substantial efforts have been made to develop RSV vaccines and vaccine-like monoclonal antibodies to prevent acute RSV LRTI. Prevention of acute disease could improve long-term lung health, with potential effects on wheezing, asthma, and chronic lung disease. This Personal View describes assessments that should be initiated during clinical trials and continued after licensure to fully evaluate the effect of RSV preventive interventions. These assessments include recording the incidence of RSV-specific LRTI and all-cause LRTI through two RSV seasons, and assessment of the prevalence and severity of recurrent wheezing or asthma in children aged up to 6 years. Standardised assessments in diverse settings are needed to fully determine the effect of interventions for the prevention of RSV disease.

Respiratory-syncytial-virus- and rhinovirus-related bronchiolitis in children aged <2 years in an English district general hospital

BACKGROUND

Bronchiolitis is the most common reason for hospitalization in young children. In addition to respiratory syncytial virus (RSV), other viruses have been increasingly implicated. Guidance on testing has also changed.

AIMS

To compare clinicopathological outcomes in young children admitted with bronchiolitis due to RSV in comparison with rhinovirus (RV), and identify associated risk/epidemiological factors.

METHODS

Children aged less than two years admitted to hospital with a clinical diagnosis of bronchiolitis with positive results for either RSV or RV were included in this study. Polymerase-chain-reaction-negative cases using an extended respiratory virus panel served as a control group. Retrospective data were collected on sex, risk factors, respiratory support, intravenous fluids and antibiotics. Outcomes such as length of stay (LOS) and need for transfer to the high-dependency unit/paediatric intensive care unit were included.

FINDINGS

Two hundred and twenty-seven out of 437 nasopharyngeal aspirate samples were positive for either RSV (N = 162) or RV (N = 65). The median age of cases was three months and 75% had at least one risk factor. Risk factors were higher in the RV group (P = 0.004). RV accounted for the majority of cases outside the RSV season (P < 0.01). RV-associated bronchiolitis had a longer LOS (more than seven days) (P < 0.05) and increased need for chest X-rays and/or antibiotics (P < 0.05). Use of intravenous fluids and respiratory support were higher in the RV group, but the difference was not significant.

CONCLUSIONS

RV is the second most common pathogen associated with bronchiolitis and is isolated all year round. This may be important in those with risk factors resulting in prolonged LOS. Further research is necessary to establish the exact role of RV in this common condition, particularly outside the traditional RSV season.

Transcriptome assists prognosis of disease severity in respiratory syncytial virus infected infants

Respiratory syncytial virus (RSV) causes infections that range from common cold to severe lower respiratory tract infection requiring high-level medical care. Prediction of the course of disease in individual patients remains challenging at the first visit to the pediatric wards and RSV infections may rapidly progress to severe disease. In this study we investigate whether there exists a genomic signature that can accurately predict the course of RSV. We used early blood microarray transcriptome profiles from 39 hospitalized infants that were followed until recovery and of which the level of disease severity was determined retrospectively. Applying support vector machine learning on age by sex standardized transcriptomic data, an 84 gene signature was identified that discriminated hospitalized infants with eventually less severe RSV infection from infants that suffered from most severe RSV disease. This signature yielded an area under the receiver operating characteristic curve (AUC) of 0.966 using leave-one-out cross-validation on the experimental data and an AUC of 0.858 on an independent validation cohort consisting of 53 infants. A combination of the gene signature with age and sex yielded an AUC of 0.971. Thus, the presented signature may serve as the basis to develop a prognostic test to support clinical management of RSV patients.

Association of nasopharyngeal microbiota profiles with bronchiolitis severity in infants hospitalised for bronchiolitis

Little is known about the relationship between the specific airway microbiota composition and severity of bronchiolitis. We aimed to identify nasopharyngeal microbiota profiles and link these profiles to acute severity in infants hospitalised for bronchiolitis.We conducted a multicentre prospective cohort study of 1005 infants (age <1 year) hospitalised for bronchiolitis over three winters, 2011-2014. By applying a 16S rRNA gene sequence and clustering approach to the nasopharyngeal aspirates collected within 24 h of hospitalisation, we determined nasopharyngeal microbiota profiles and their association with bronchiolitis severity. The primary outcome was intensive care use, i.e. admission to an intensive care unit or use of mechanical ventilation.We identified four nasopharyngeal microbiota profiles: three profiles were dominated by one of Haemophilus, Moraxella or Streptococcus, while the fourth profile had the highest bacterial richness. The rate of intensive care use was highest in infants with a Haemophilus-dominant profile and lowest in those with a Moraxella-dominant profile (20.2% versus 12.3%; unadjusted OR 1.81, 95% CI 1.07-3.11, p=0.03). After adjusting for 11 patient-level confounders, the rate remained significantly higher in infants with Haemophilus-dominant profiles (OR 1.98, 95% CI 1.08-3.62, p=0.03). These findings were externally validated in a separate cohort of 307 children hospitalised for bronchiolitis.

Association of a PAI-1 Gene Polymorphism and Early Life Infections with Asthma Risk, Exacerbations, and Reduced Lung Function

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) is induced in airways by virus and may mediate asthmatic airway remodeling. We sought to evaluate if genetic variants and early life lower respiratory infections jointly affect asthma risk.

METHODS

We included Latino children, adolescents, and young adults aged 8-21 years (1736 subjects with physician-diagnosed asthma and 1747 healthy controls) from five U.S. centers and Puerto Rico after excluding subjects with incomplete clinical or genetic data. We evaluated the independent and joint effects of a PAI-1 gain of function polymorphism and bronchiolitis / Respiratory Syncytial Virus (RSV) or other lower respiratory infections (LRI) within the first 2 years of life on asthma risk, asthma exacerbations and lung function.

RESULTS

RSV infection (OR 9.9, 95%CI 4.9-20.2) and other LRI (OR 9.1, 95%CI 7.2-11.5) were independently associated with asthma, but PAI-1 genotype was not. There were joint effects on asthma risk for both genotype-RSV (OR 17.7, 95% CI 6.3-50.2) and genotype-LRI (OR 11.7, 95% CI 8.8-16.4). A joint effect of genotype-RSV resulted in a 3.1-fold increased risk for recurrent asthma hospitalizations. In genotype-respiratory infection joint effect analysis, FEV1% predicted and FEV1/FVC % predicted were further reduced in the genotype-LRI group (β -2.1, 95% CI -4.0 to -0.2; β -2.0, 95% CI -3.1 to -0.8 respectively). Similarly, lower FEV1% predicted was noted in genotype-RSV group (β -3.1, 95% CI -6.1 to -0.2) with a trend for lower FEV1/FVC % predicted.

CONCLUSIONS

A genetic variant of PAI-1 together with early life LRI such as RSV bronchiolitis is associated with an increased risk of asthma, morbidity, and reduced lung function in this Latino population.

A clustering approach to identify severe bronchiolitis profiles in children

OBJECTIVE

Although bronchiolitis is generally considered a single disease, recent studies suggest heterogeneity. We aimed to identify severe bronchiolitis profiles using a clustering approach.

METHODS

We analysed data from two prospective, multicentre cohorts of children younger than 2 years hospitalised with bronchiolitis, one in the USA (2007-2010 winter seasons, n=2207) and one in Finland (2008-2010 winter seasons, n=408). Severe bronchiolitis profiles were determined by latent class analysis, classifying children based on clinical factors and viral aetiology.

RESULTS

In the US study, four profiles were identified. Profile A (12%) was characterised by history of wheezing and eczema, wheezing at the emergency department (ED) presentation and rhinovirus infection. Profile B (36%) included children with wheezing at the ED presentation, but, in contrast to profile A, most did not have history of wheezing or eczema; this profile had the largest probability of respiratory syncytial virus infection. Profile C (34%) was the most severely ill group, with longer hospital stay and moderate-to-severe retractions. Profile D (17%) had the least severe illness, including non-wheezing children with shorter length of stay. Two of these profiles (A and D) were replicated in the Finnish cohort; a third group ('BC') included Finnish children with characteristics of profiles B and/or C in the US population.

CONCLUSIONS

Several distinct clinical profiles (phenotypes) were identified by a clustering approach in two multicentre studies of children hospitalised for bronchiolitis. The observed heterogeneity has important implications for future research on the aetiology, management and long-term outcomes of bronchiolitis, such as future risk of childhood asthma.

Advancing our understanding of infant bronchiolitis through phenotyping and endotyping: clinical and molecular approaches

INTRODUCTION

Bronchiolitis is a major public health problem worldwide. However, no effective treatment strategies are available, other than supportive care.

AREAS COVERED

Although bronchiolitis has been considered a single disease diagnosed based on clinical characteristics, emerging evidence supports both clinical and pathobiological heterogeneity. The characterization of this heterogeneity supports the concept that bronchiolitis consists of multiple phenotypes or consistent grouping of characteristics. Expert commentary: Using unbiased statistical approaches, multidimentional clinical characteristics will derive bronchiolitis phenotypes. Furthermore, molecular and systems biology approaches will, by linking pathobiology to phenotype, identify endotypes. Large cohort studies of bronchiolitis with comprehensive clinical characterization and system-wide profiling of the '-omics' data (e.g., host genome, transcriptome, epigenome, viral genome, microbiome, metabolome) should enhance our ability to molecularly understand these phenotypes and lead to more targeted and personalized approaches to bronchiolitis treatment.

Rhinovirus species and clinical characteristics in the first wheezing episode in children

The clinical data on the first wheezing episodes induced by different rhinovirus (RV) species are still limited. We aimed to investigate the prevalence of RV genotypes, sensitization status, and clinical characteristics of patients having a respiratory infection caused by either different RV species or other respiratory viruses. The study enrolled 111 patients (aged 3–23 months, 79% hospitalized, 76% with RV infection) with the first wheezing episode. RV‐specific sequences were identified by partial sequencing of VP4/VP2 and 5′ non‐coding regions with 80% success rate. The investigated clinical and laboratory variables included atopic characteristics and illness severity, parental atopic illnesses, and parental smoking. Of the study children, 56% percent had >1 atopic characteristic (atopy, eczema and/or blood eosinophil count >0.4 × 10⁹/L) and 23% were sensitised to allergens. RV‐C was detected in 58% of RV positive samples, followed by RV‐A (20%) and RV‐B (1.2%). Children with RV‐A and RV‐C induced wheezing were older (P = 0.014) and had more atopic characteristics (P = 0.001) than those with non‐RV. RV‐A and RV‐C illnesses had shorter duration of preadmission symptoms and required more bronchodilator use at the ward than non‐RV illnesses (both P < 0.05, respectively). RV‐C is the most common cause of severe early wheezing. Atopic and illness severity features are associated with children having RV‐A or RV‐C induced first wheezing episode rather than with children having a non‐RV induced wheezing. J. Med. Virol. 88:2059–2068, 2016. © 2016 Wiley Periodicals, Inc.

Does Viral Co-Infection Influence the Severity of Acute Respiratory Infection in Children?

Background

Multiple viruses are often detected in children with respiratory infection but the significance of co-infection in pathogenesis, severity and outcome is unclear.

Objectives

To correlate the presence of viral co-infection with clinical phenotype in children admitted with acute respiratory infections (ARI).

Methods

We collected detailed clinical information on severity for children admitted with ARI as part of a Spanish prospective multicenter study (GENDRES network) between 2011–2013. A nested polymerase chain reaction (PCR) approach was used to detect respiratory viruses in respiratory secretions. Findings were compared to an independent cohort collected in the UK.

Results

204 children were recruited in the main cohort and 97 in the replication cohort. The number of detected viruses did not correlate with any markers of severity. However, bacterial superinfection was associated with increased severity (OR: 4.356; P-value = 0.005), PICU admission (OR: 3.342; P-value = 0.006), higher clinical score (1.988; P-value = 0.002) respiratory support requirement (OR: 7.484; P-value < 0.001) and longer hospital length of stay (OR: 1.468; P-value < 0.001). In addition, pneumococcal vaccination was found to be a protective factor in terms of degree of respiratory distress (OR: 2.917; P-value = 0.035), PICU admission (OR: 0.301; P-value = 0.011), lower clinical score (-1.499; P-value = 0.021) respiratory support requirement (OR: 0.324; P-value = 0.016) and oxygen necessity (OR: 0.328; P-value = 0.001). All these findings were replicated in the UK cohort.

Conclusion

The presence of more than one virus in hospitalized children with ARI is very frequent but it does not seem to have a major clinical impact in terms of severity. However bacterial superinfection increases the severity of the disease course. On the contrary, pneumococcal vaccination plays a protective role.

Impact of bacteria in nasal aspirates on disease severity of bronchiolitis

BACKGROUND

The effect of potentially pathogenic bacteria (PPB) on disease severity in patients with bronchiolitis is understudied.

METHODS

This prospective study was carried out in the Children's Hospital of Soochow University during the 2012-2013 autumn and winter seasons. We enrolled consecutive children < 2 years of age hospitalized with an attending physician's diagnosis of bronchiolitis. Nasopharyngeal aspirate samples were tested for multiple respiratory viruses and cultured for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus.

RESULTS

In all, 30% (188 patients) were positive for Strep. pneumoniae, H. influenzae, M. catarrhalis, and Staph. aureus. Length of stay (LOS) for patients with PPB was 4.0 days (interquartile range, IQR, 25th-75th percentile: 3.0-6.0 days) versus 3.0 days (IQR, 3.0-5.0 days) for patients without PPB (p < 0.001). However, requirement and duration of supplemental oxygen were not significantly different between the two groups. H. influenzae was an independent risk factor for hospital LOS ≥ 5.0 days (adjusted odds ratio, 1.75; 95% confidence interval, 1.06-2.91). The presence of PPB was not associated with increased risk of supplemental oxygen requirement.

CONCLUSIONS

Our study demonstrated that pediatricians should evaluate for PPB in patients with bronchiolitis, especially when they present with RSV infection, fever or percentage of neutrophils > 40%. The presence of H. influenzae in nasal aspirates is associated with longer LOS in patients with bronchiolitis.

Association Between Hyponatremia and Higher Bronchiolitis Severity Among Children in the ICU With Bronchiolitis

BACKGROUND AND OBJECTIVES

It remains unclear whether hyponatremia independently predicts a higher severity of bronchiolitis in children. The objective of this study was to investigate the association between hyponatremia and bronchiolitis severity in children hospitalized in the ICU for bronchiolitis.

METHODS

We conducted a 16-center, prospective cohort study of hospitalized children aged <2 years with bronchiolitis during the winters of 2007 through 2010. Patients were classified into 2 groups (normonatremic [135-145 mEq/L] and hyponatremic [<135 mEq/L]) based on the first-measured serum sodium concentration on the day of hospitalization. Outcomes were use of mechanical ventilation and ICU length of stay (LOS). To examine the association of sodium status with outcomes, we fit logistic and linear regression models with propensity score adjustment.

RESULTS

Of 231 children hospitalized in the ICU for bronchiolitis, 193 (84%) were categorized into the normonatremic group and 38 (16%) into the hyponatremic group. Compared with children with normonatremia, those with hyponatremia had higher risks of mechanical ventilation use (40% vs 58%; P = .04) and longer ICU LOS (median, 3 vs 6 days; P = .007). Likewise, in the adjusted analyses, children with hyponatremia had significantly higher risks of mechanical ventilation use (odds ratio, 2.14 [95% confidence interval, 1.03-4.48; P = .04) and longer ICU LOS (β-coefficient, 2.21 days [95% confidence interval, 0.68-3.73; P = .005]).

CONCLUSIONS

In this prospective, multicenter study of children hospitalized for bronchiolitis, hyponatremia on the day of hospitalization was associated with a higher severity of disease. Our data support hyponatremia as a prognostic factor that might improve the ability of clinicians to predict the disease course of children with severe bronchiolitis.

Imaging of small airways and emphysema

High-resolution chest computed tomography (CT) is one of the most useful techniques available for imaging bronchiolitis because it shows highly specific direct and indirect imaging signs. The distribution and combination of these various signs can further classify bronchiolitis as either cellular/inflammatory or fibrotic/constrictive. Emphysema is characterized by destruction of the airspaces, and a brief discussion of imaging findings of this class of disease is also included. Typical CT findings include destruction of airspace, attenuated vasculatures, and hyperlucent as well as hyperinflated lungs.

Tissue tropism, pathology and pathogenesis of enterovirus infection

Enteroviruses are very common and cause infections with a diverse array of clinical features. Enteroviruses are most frequently considered by practising pathologists in cases of aseptic meningitis, encephalitis, myocarditis and disseminated infections in neonates and infants. Congenital infections have been reported and transplacental transmission is thought to occur. Although skin biopsies during hand, foot and mouth disease are infrequently obtained, characteristic dermatopathological findings can be seen. Enteroviruses have been implicated in lower respiratory tract infections. This review highlights histopathological features of enterovirus infection and discusses diagnostic modalities for formalin-fixed paraffin-embedded tissues and their associated pitfalls. Immunohistochemistry can detect enterovirus antigen within cells of affected tissues; however, assays can be non-specific and detect other viruses. Molecular methods are increasingly relied upon but, due to the high frequency of asymptomatic enteroviral infections, clinical-pathological correlation is needed to determine significance. Of note, diagnostic assays on central nervous system or cardiac tissues from immunocompetent patients with prolonged disease courses are most often negative. Histopathological, immunohistochemical and molecular studies performed on clinical specimens also provide insight into enteroviral tissue tropism and pathogenesis.

Risk factors for requiring intensive care among children admitted to ward with bronchiolitis

OBJECTIVE

To examine risk factors for transfer of bronchiolitis patients from the ward to the intensive care unit (ICU) and/or initiation of critical care interventions.

METHODS

We performed a 16-center, prospective cohort study of hospitalized children age <2 years with bronchiolitis. During the winters of 2007 to 2010, researchers collected clinical data and nasopharyngeal aspirates from study participants. The primary outcome was late intensive care use, defined as a transfer to the ICU and/or use of mechanical ventilation (regardless of location) after the child's first inpatient day.

RESULTS

Among 2104 children hospitalized with bronchiolitis, 1762 (84%) were identified as initial ward patients, comprising the analysis cohort. The median age was 4 months (interquartile range, 2-9 months), and 1048 (59%) were boys. The most frequently detected pathogens were respiratory syncytial virus (72%) and rhinovirus (25%). After the first inpatient day, 47 (3%; 95% confidence interval, 2-4) were subsequently transferred to the ICU or required mechanical ventilation. In the multivariable logistic regression model predicting subsequent transfer to the ICU or mechanical ventilation use, the significant predictors were birth weight <5 pounds (odds ratio, 2.28; 95% confidence interval, 1.30-4.02; P = .004) and respiratory rate high of ≥ 70 breaths/min on the first inpatient day (odds ratio, 4.64; 95% confidence interval, 2.86-7.53; P < .001).

CONCLUSIONS

In this multicenter study of children hospitalized with bronchiolitis, low birth weight and tachypnea were significantly associated with subsequent transfer to the ICU and/or use of mechanical ventilation.

Respiratory syncytial virus genomic load and disease severity among children hospitalized with bronchiolitis: multicenter cohort studies in the United States and Finland

BACKGROUND

We investigated whether children with a higher respiratory syncytial virus (RSV) genomic load are at a higher risk of more-severe bronchiolitis.

METHODS

Two multicenter prospective cohort studies in the United States and Finland used the same protocol to enroll children aged <2 years hospitalized for bronchiolitis and collect nasopharyngeal aspirates. By using real-time polymerase chain reaction analysis, patients were classified into 3 genomic load status groups: low, intermediate, and high. Outcome measures were a length of hospital stay (LOS) of ≥3 days and intensive care use, defined as admission to the intensive care unit or use of mechanical ventilation.

RESULTS

Of 2615 enrolled children, 1764 (67%) had RSV bronchiolitis. Children with a low genomic load had a higher unadjusted risk of having a length of stay of ≥3 days (52%), compared with children with intermediate and those with high genomic loads (42% and 51%, respectively). In a multivariable model, the risk of having a length of stay of ≥3 days remained significantly higher in the groups with intermediate (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.20-1.69) and high (OR, 1.58; 95% CI, 1.29-1.94) genomic loads. Similarly, children with a high genomic load had a higher risk of intensive care use (20%, compared with 15% and 16% in the groups with low and intermediate genomic loads, respectively). In a multivariable model, the risk remained significantly higher in the group with a high genomic load (OR, 1.43; 95% CI, 1.03-1.99).

CONCLUSION

Children with a higher RSV genomic load had a higher risk for more-severe bronchiolitis.

Infectious pathogens and bronchiolitis outcomes

Bronchiolitis is a common early childhood illness and an important cause of morbidity, it is the number one cause of hospitalization among US infants. Bronchiolitis is also an active area of research, and recent studies have advanced our understanding of this illness. Although it has long been the conventional wisdom that the infectious etiology of bronchiolitis does not affect outcomes, a growing number of studies have linked specific pathogens of bronchiolitis (e.g., rhinovirus) to short- and long-term outcomes, such as future risk of developing asthma. The authors review the advent of molecular diagnostic techniques that have demonstrated diverse pathogens in bronchiolitis, and they review recent studies on the complex link between infectious pathogens of bronchiolitis and the development of childhood asthma.