Epidemiology of hospitalization for acute bronchiolitis in children: differences between RSV and non-RSV bronchiolitis

Seasonal peaks and risk factors of respiratory syncytial virus infections related hospitalization of preterm infants in Taiwan

Objectives

To assess the nationwide seasonal peaks, risk factors, and utilization of medical resources of respiratory syncytial virus-associated hospitalization (RSVH) in preterm infants in Taiwan.

Study design

A Taiwan nationwide birth cohort was extracted from the Birth Certificate Application Database during 2007–2009 and prospectively linked to the National Health Insurance database. We evaluated the seasonal peaks and risk factors (gestational age [GA], chronologic age [CA], and bronchopulmonary dysplasia [BPD]) associated with the RSVH of preterm infants. The length of hospital stays (LOS), care in intensive care unit (ICU), and use of mechanical ventilation (MV) were also analyzed.

Results

There is a total duration of 9 months of RSVH season in Taiwan, three seasonal peaks and two seasonal peaks of RSVH in preterm infants with BPD and without BPD, respectively. Preterm infants had significantly higher RSVH rate than term infants (2.6% vs 0.9%, p<0.0001). Preterm infants born at 29–35 weeks of gestational age (wGA) with BPD had significantly higher RSVH rate than those without BPD (p<0.0001). Preterm infants without BPD born at < 32 wGA had higher RSVH rate than those born at 33–35 wGA (p<0.0001). Overall, 56.4% of RSVH occurred within 9 months of CA. Preterm infants with BPD had significantly higher ICU admission rate within 18 months of CA (p<0.0001), MV usage within 12 months of CA (p<0.0001) and LOS within 18 months of CA (p<0.001) than those without BPD. RSVH occurred within 6 months of CA was significantly associated with higher ICU admission rate (p<0.0001), MV usage (p = 0.0002) and longer LOS (p<0.001) in preterm infants without BPD.

Conclusions

There is a total duration of 9 months of RSVH season in Taiwan. Preterm < 32 wGA, BPD, and CA within 6 months were risk factors of RSVH which also contribute to higher utilization of medical resources.

Interaction between healthcare professionals and parents is a key determinant of parental distress during childhood hospitalisation for respiratory syncytial virus infection (European RSV Outcomes Study [EROS])

Aim

We characterised the distress that parents experienced when their child was hospitalised for respiratory syncytial virus (RSV) infection.

Methods

This survey‐based, observational study was conducted during 2014–2015. Meetings were held in Spain and Italy, with 24 parents of RSV hospitalised infants and 11 healthcare professionals experienced in RSV, which identified 110 factors related to parental distress. The resulting questionnaire was completed by another 105 Spanish and Italian parents and 56 healthcare professionals, to assess the impact these factors had on parental distress, using a scale from 0 to 10 (very unimportant to very important).

Results

The five most important factors for parents were: healthcare professionals’ awareness of the latest developments, readmission, reinfections, painful procedures and positive experiences with healthcare professionals. Healthcare professionals associated only medical factors with a meaningful impact on parents. Half of the six medical factors were given similar importance by both groups and the overall scoring for the 110 factors was comparable, with a correlation coefficient of 0.80. A primary concern on discharge was ongoing support.

Conclusion

The relationship between parents and healthcare professionals was a significant factor in determining parental distress. Healthcare professionals appeared to have a good understanding of the overall impact on parents, particularly the key medical factors.

Efficacy of a Novel Palivizumab Prophylaxis Protocol for Respiratory Syncytial Virus Infection in Congenital Heart Disease: A Multicenter Study

OBJECTIVE

To analyze the efficacy of a novel palivizumab protocol for hemodynamically significant congenital heart disease (hsCHD) in subtropical areas without clear respiratory syncytial virus seasonality.

STUDY DESIGN

Since July 2013, the National Health Insurance program has provided reimbursement for palivizumab prophylaxis with a novel monthly protocol in selected patients with hsCHD under 1 year of age. We performed a multicenter study to assess the trend of respiratory syncytial virus hospitalizations in patients with hsCHD from 2010 to 2016 during the prepalivizumab, transition, and postpalivizumab periods, and compared treatment and propensity-matched control groups.

RESULTS

A total of 747 patients were enrolled in the study group and 809 in the control group. The male:female was 836:720. Cyanotic CHD was observed in 42.9% of patients. The mean age at diagnosis of CHD was 32.9 days. After 516 685 patient-days of follow-up and a mean of 3.9 doses of palivizumab in the treatment group, respiratory syncytial virus hospitalization rates decreased by 53% and 49% before and after match compared with the control group (P = .009 and .029, respectively). Hospitalization days and intensive care unit admission rate also decreased similarly in the treatment group. The efficacy of this protocol was more prominent in patients with cyanotic hsCHD. The annual respiratory syncytial virus-associated hospitalization rates also decreased significantly from the prepalivizumab to the palivizumab period (from 4.8% to 2.0%; P = .038).

CONCLUSION

Palivizumab prophylaxis through the novel monthly protocol for patients with hsCHD is effective in reducing respiratory syncytial virus-related hospitalizations.

The cost-effectiveness of hypertonic saline inhalations for infant bronchiolitis: a decision analysis

BACKGROUND

This study evaluated the cost-effectiveness of hypertonic saline (HS) inhalations for infant bronchiolitis, compared to normal saline inhalations or standard treatment without inhalations as controls.

METHODS

The decision tree in the decision analysis was used to calculate the expected costs. Actual cost data were obtained from our retrospective case-control study on bronchiolitis treatment. The effectiveness of treatment, based on the hospitalization rate of those admitted to the emergency department and the length of stay (LOS) of those who were hospitalized, was collected from previous studies. For the effectiveness estimations, we made a meta-analysis summarizing the results of the meta-analysis of the Cochrane review in 2013 and the results of 10 studies published after it.

RESULTS

The mean hospitalization rate was 24.7% in the HS inhalation group and 32.6% in the control group [risk ratio: 0.80, 95% confidence interval (CI) 0.67-0.96] and the mean LOS was 3.736 (HS group) and 4.292 (controls) days (mean difference: - 0.55 days, 95% CI - 0.96 to - 0.15), respectively. The expected costs per patient, when both inpatients and outpatients were included, were €816 ($1111) in the HS inhalation group and €962 ($1310) in the control group. The expected costs per hospitalization, when only inpatients were included, were €2600 ($3540) in the HS inhalation group and €2890 ($3935) in the control group.

CONCLUSIONS

HS inhalations slightly reduced the expected hospitalization costs of infant bronchiolitis. However, the low effectiveness, rather than the cost, is the factor that will limit the use of HS inhalations in infant bronchiolitis.

Association between single nucleotide polymorphisms in TLR4, TLR2, TLR9, VDR, NOS2 and CCL5 genes with acute viral bronchiolitis

Background

Acute viral bronchiolitis is the leading cause of hospitalization among infants during the first year of life. Most infants hospitalized for bronchiolitis do not present risk factors and are otherwise healthy. Our objective was to determine the genetic features associated with the risk and a severe course of bronchiolitis.

Methods

We prospectively evaluated 181 infants with severe bronchiolitis admitted at three hospitals over a 2-year period, who required oxygen therapy. The control group consisted of 536 healthy adults. Patients were evaluated for the presence of comorbidities (premature birth, chronic respiratory disease, and congenital heart disease), underwent nasopharyngeal aspirate testing for virus detection by multiplex-PCR, and SNPs identification in immune response genes. Patient outcomes were assessed.

Results

We observed association between SNP rs2107538*CCL5 and bronchiolitis caused by respiratory syncytial virus(RSV) and RSV-subtype-A, and between rs1060826*NOS2 and bronchiolitis caused by rhinovirus. SNPs rs4986790*TLR4, rs1898830*TLR2, and rs2228570*VDR were associated with progression to death. SNP rs7656411*TLR2 was associated with length of oxygen use; SNPs rs352162*TLR9, rs187084*TLR9, and rs2280788*CCL5 were associated with requirement for intensive care unit admission; while SNPs rs1927911*TLR4, rs352162*TLR9, and rs2107538*CCL5 were associated with the need for mechanical ventilation.

Conclusions

Our findings provide some evidence that SNPs in CCL5 and NOS2 are associated with presence of bronchiolitis and SNPs in TLR4, TLR2, TLR9, VDR and CCL5 are associated with severity of bronchiolitis.

•

SNPs in CCL5 and NOS2 genes are associated with presence of bronchiolitis.

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SNPs in TLR4, TLR2 and TLR9, genes are associated with severity of bronchiolitis.

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SNPs in VDR and CCL5 genes are associated with severity of bronchiolitis.

Respiratory syncytial virus in Brazilian infants - Ten years, two cohorts

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There was 33.1% and 70.3% of RSV patients, respectively, in 2004 and 2014.

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The month of incidence was different between the cohorts.

•

First cohort: higher age at attendance and number of co-morbidities.

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Second cohort: lower birth weight and gestational age.

Background

Each year, a considerable amount of children will experience at least one episode of acute viral bronchiolitis (AVB) during their first year of life. About 10% of them will be hospitalized, with significant physical and economic burdens.

Objectives

To compare two cohorts of infants with AVB, from same region, in a ten-year interval, regarding epidemiologic factors and viral etiology.

Study design

Cohorts: 142 (2004) and 172 (2014) infants at ages zero to 12 months; clinical diagnosis of AVB; medical care in hospital and genetic screening of nasopharyngeal secretion for respiratory viruses.

Results

The comparative analysis showed a difference in the percentage of respiratory syncytial virus (RSV) positive patients [2004 (33.1%); 2014 (70.3%)] (p < 0.01). No differences were noted regarding gender, breastfeeding, tobacco exposure, crowding and maternal education. There was a difference as to the month of incidence (seasonality) of AVB (higher in April 2014). There was a higher age at attendance in the first cohort, and lower birth weight and gestational age ratios in the second cohort (p < 0.05). There were no differences in hospitalization time, need of mechanical ventilation and number of deaths, however a difference regarding co-morbidities was noted (higher in 2004) (p < 0.001).

Conclusion

None of the analyzed variables had an impact on severity features. Virology and immunology must be considered in this kind of situation, by studying genetic variants and the maturation of the immune system in AVB by RSV or other viruses.

[Validation study of an acute bronchiolitis severity scale to determine admission to a Paediatric Intensive Care Unit]

INTRODUCTION

At present, there are few validated scoring tests for assessing acute bronchiolitis (AB) severity, and limited information on their test power. The aim of the present study is to evaluate the validity of an acute bronchiolitis severity score (ABSS) to help in deciding PICU admission.

PATIENTS AND METHOD

Prospective, descriptive, observational study of previously healthy infants under 1 year of age with AB, where the ABSS was used to compare severity as regards the need for PICU admission. The sample size was estimated as at least 175 patients. The research team was trained in the use of ABSS. All patients in the study were evaluated with ABSS daily, as well as in the case of clinical deterioration. The initial and maximum ABSS scores were contrasted to the need for PICU admission. A receiver operative curve was constructed, and the area under the curve was calculated, and the optimum point of sensitivity / specificity was estimated.

RESULTS

The study included a total of 190 patients (male / female: 58% / 42%). PICU was required in 11 (6%). The mean± SD ABSS-maximal score for patients who required and did not require PICU was 10.55± 1.12 and 6.35± 2.3, respectively (P<.001). The AUC for ABSS-maximal was 0.94 (P<.001, 95% CI: 0.90-0.98). The optimal cut-off point was set at ≥10 points for a sensitivity of 82% and a specificity of 91%.

CONCLUSIONS

ABSS estimates the severity of AB regarding the need for PICU admission, with a sensitivity and specificity of clinical usefulness.

Epidemiology of bronchiolitis: a description of emergency department visits and hospitalizations in Puerto Rico, 2010-2014

BACKGROUND

Little is known about the epidemiology of bronchiolitis as a clinical diagnosis and its impact on emergency department visits and hospitalizations in tropical and semitropical regions. We described the epidemiology of bronchiolitis emergency visits and hospitalizations, its temporal trend and geographic distribution in Puerto Rico between 2010 and 2014.

METHODS

We performed a retrospective descriptive analysis of a representative sample of privately insured children with bronchiolitis from January 2010 to December 2014. Data was provided by the largest private health insurer in Puerto Rico and identified children < 24 months of age with bronchiolitis by International Classification of Diseases, Ninth Revision code 466, 466.11, and 466.19. Chi-square and one-way ANOVA compared sex, age, diagnosis, and severity across the years. Joinpoint Poisson regression analysis evaluated the temporal trend distribution of bronchiolitis hospitalizations per calendar year. A P value less than 0.05 was statistically significant.

RESULTS

During the study period, the annual proportion of emergency department visits and hospitalizations due to bronchiolitis increased from 3 to 5%, and 26 to 38%, respectively. The annual incidence rate of hospitalizations was 3.2 per 1000 privately insured children < 24 months. Non-RSV bronchiolitis was the most frequent diagnosis (51%). Hospitalizations occurred year-round, but increased significantly from August through December. Most children hospitalized resided in the metropolitan San Juan (35%) and surrounding urban areas. Total hospital charges decreased from $3.78 to $3.74 million, with an average cost per hospitalization of $4320.12 (11.3% increase; P = 0.0015).

CONCLUSIONS

This is the first study that evaluates the epidemiological characteristics of bronchiolitis in a primarily Hispanic population, living in a tropical country, and using data from a privately insured population. We found a small but significant increase in proportion of emergency visits and hospitalizations. Temporal trend shows year-round hospitalizations with an earlier seasonal peak and longer duration, consistent with Puerto Rico's seasonal rainfall throughout the study period. Further studies are needed to elucidate whether this epidemiologic pattern can also be seen in publicly insured children and whether Hispanic ethnicity is a risk factor for increased hospitalizations or is related to health disparities in the US healthcare system.

The Burden and Long-term Respiratory Morbidity Associated with Respiratory Syncytial Virus Infection in Early Childhood

INTRODUCTION

The REGAL (RSV Evidence-a Geographical Archive of the Literature) series provide a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. The objective of this fifth publication was to determine the long-term respiratory morbidity associated with RSV lower respiratory tract infection (RSV LRTI) in early life.

METHODS

A systematic review was undertaken for articles published between January 1, 1995 and December 31, 2015. This was supplemented by inclusion of papers published whilst drafting the manuscript. Studies reporting data on the incidence and long-term wheezing and asthma following RSV LRTI in early life were included. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULTS

A total of 2337 studies were identified of which 74 were included. Prospective, epidemiologic studies consistently demonstrated that RSV LRTI is a significant risk factor for on-going respiratory morbidity characterized by transient early wheezing and recurrent wheezing and asthma within the first decade of life and possibly into adolescence and adulthood (high SOE). RSV LRTI was also associated with impaired lung function in these children (high SOE). Respiratory morbidity has been shown to result in reduced quality of life and increased healthcare resource use (moderate SOE). The mechanisms through which RSV contributes to wheezing/asthma development are not fully understood, but appear to relate to the viral injury, preexisting abnormal lung function and/or other factors that predispose to wheezing/asthma, including genetic susceptibility, altered immunology, eosinophilia, and associated risk factors such as exposure to environmental tobacco smoke (high SOE).

CONCLUSION

There is growing evidence that RSV LRTI in early childhood is associated with long-term wheezing and asthma and impaired lung function. Future research should aim to fully elucidate the pathophysiological mechanisms through which RSV causes recurrent wheezing/asthma.

Efficacy of palivizumab prophylaxis on the frequency of RSV-associated lower respiratory tract infections in preterm infants: determination of the ideal target population for prophylaxis

Respiratory syncytial virus (RSV) prophylaxis in high-risk infants is an effective intervention for the prevention of severe disease. The aim of this study was to determine the ideal target preterm population that might benefit from palivizumab prophylaxis by establishing the main risk factors for acute RSV-related infections. Former premature infants born with a gestational age ≤37 weeks and ≤1 year of age at the beginning of the RSV season and admitted with respiratory infection were included. RSV status was evaluated by RSV strip test in all infants. RSV-positive and -negative infants were compared in terms of demographic features, risk factors, requirement of hospitalisation and palivizumab administration. A total of 202 preterm infants under 1 year of age were enrolled. The RSV test was positive in 34 (16.8%) infants. Maternal age was significantly lower in RSV-positive infants compared with RSV-negative infants (p = 0.03). RSV-positive infants were found to be significantly discharged during the RSV season (p = 0.03). RSV-positive infants required significantly higher rates of hospitalisation and need for mechanical ventilation. Of the RSV-positive infants, 28 (82%) had a gestational age ≥29 weeks. Seventeen (77%) RSV-positive infants that required hospitalisation were ≥29 weeks of gestation. All infants with a gestational age ≥29 weeks and without palivizumab prophylaxis developed RSV infection. Palivizumab prophylaxis should be implemented into guidelines to cover preterm infants with a gestational age >29 weeks. Palivizumab prophylaxis should also be considered in high-risk infants ≤6 months of age during the RSV season.

Defining the Risk and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Infants with Congenital Heart Disease

Introduction

The REGAL (RSV Evidence—a Geographical Archive of the Literature) series provide a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This fourth publication covers the risk and burden of RSV infection in infants with congenital heart disease (CHD).

Methods

A systematic review was undertaken for articles published between January 1, 1995 and December 31, 2015 across PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov. Studies reporting data for hospital visits/admissions for RSV infection among children with CHD as well as studies reporting RSV-associated morbidity, mortality, and healthcare costs were included. The focus was on children not receiving RSV prophylaxis. Study quality and strength of evidence (SOE) were graded using recognized criteria.

Results

A total of 1325 studies were identified of which 38 were included. CHD, in particular hemodynamically significant CHD, is an independent predictor for RSV hospitalization (RSVH) (high SOE). RSVH rates were generally high in young children (<4 years) with CHD (various classifications), varying between 14 and 357/1000 (high SOE). Children (<6 years) with RSV infection spent 4.4–14 days in hospital, with up to 53% requiring intensive care (high SOE). Infants (<2 years) with CHD had a more severe course of RSVH than those without CHD (high SOE). Case fatality rates of up to 3% were associated with RSV infection in children with CHD (high SOE). RSV infection in the perioperative period of corrective surgery and nosocomial RSV infection in intensive care units also represent important causes of morbidity (moderate SOE).

Conclusion

CHD poses a significant risk for RSVH and subsequent morbidity and mortality. RSV infection often complicates corrective heart surgery. To reduce the burden and improve outcomes, further research and specific studies are needed to determine the longer-term effects of severe RSV infection in young children with CHD.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-016-0142-x) contains supplementary material, which is available to authorized users.

Respiratory syncytial virus infection: an innate perspective

Respiratory syncytial virus (RSV) is a common cause of upper respiratory tract infection in children and adults. However, infection with this virus sometimes leads to severe lower respiratory disease and is the major cause of infant hospitalisations in the developed world. Several risk factors such as baby prematurity and congenital heart disease are known to predispose towards severe disease but previously healthy, full-term infants can also develop bronchiolitis and viral pneumonia during RSV infection. The causes of severe disease are not fully understood but may include dysregulation of the immune response to the virus, resulting in excessive recruitment and activation of innate and adaptive immune cells that can cause damage. This review highlights recent discoveries on the balancing act of immune-mediated virus clearance versus immunopathology during RSV infection.

High-flow oxygen therapy is more cost-effective for bronchiolitis than standard treatment-A decision-tree analysis

We evaluated the cost-effectiveness of high-flow nasal cannula (HFNC) to provide additional oxygen for infants with bronchiolitis, compared to standard low-flow therapy. The cost-effectiveness was evaluated by decision analyses, using decision tree modeling, and was based on real costs from our recently published retrospective case-control study. The data on the effectiveness of HFNC treatment were collected from earlier published retrospective studies, using admission rates to pediatric intensive care units (PICU). The analyses in the study showed that the expected treatment costs of each episode of infant bronchiolitis varied between €1,312-2,644 ($1,786-3,600) in the HFNC group and €1,598-3,764 ($2,175-5,125) in the standard treatment group. The PICU admission rates and consequential costs were lower for HFNC than for standard treatment. HFNC treatment proved more cost-effective than standard treatment in all the baseline analyses and was also more cost-effective in the sensitivity analyses, except for in the worst-case scenario analysis. In conclusion, our modeling demonstrated that HFNC was strongly cost-effective for infant bronchiolitis, compared to standard treatment because it was both more effective and less expensive. Thus, if children hospitalized for bronchiolitis need oxygen, it should be delivered as HFNC treatment. Pediatr Pulmonol. 2016;51:1393-1402. © 2016 Wiley Periodicals, Inc.

Clinical Utility of On-Demand Multiplex Respiratory Pathogen Testing among Adult Outpatients

Multiplex tests for respiratory tract infections include up to 20 targets for common pathogens, predominantly viruses. A specific therapeutic intervention is available for individuals testing positive for influenza viruses (oseltamivir), and it is potentially beneficial to identify non-influenza viruses to avoid unnecessary antibiotic use. We evaluated antimicrobial prescriptions following respiratory pathogen testing among outpatients at a large Veterans Administration (VA) medical center. Results of the FilmArray respiratory panel (BioFire, Salt Lake City, UT) from 15 December 2014 to 15 April 2015 were evaluated among 408 outpatients, and patient medical records were reviewed. Differences in antibiotic and oseltamivir prescription rates were analyzed. Among 408 patients tested in outpatient centers (emergency departments, urgent care clinics, and outpatient clinics), 295 (72.3%) were managed as outpatients. Among these 295 outpatients, 105 (35.6%) tested positive for influenza virus, 109 (36.9%) tested positive for a non-influenza virus pathogen, and 81 (27.5%) had no respiratory pathogen detected. Rates of oseltamivir and antibiotic prescriptions were significantly different among the three test groups (chi-squared values of 167.6 [P < 0.0001] and 10.48 [P = 0.005], respectively), but there was no significant difference in antibiotic prescription rates between the non-influenza virus pathogen group and those who tested negative (chi-square value, 0; P = 1.0). Among adult outpatients, testing positive for influenza virus was associated with receiving fewer antibiotic prescriptions, but no such effect was seen for those who tested positive for a non-influenza virus. These data suggest that testing for influenza viruses alone may be sufficient and more cost-effective than multiplex pathogen testing for outpatients.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

FUNDING

AbbVie.

Defining the Epidemiology and Burden of Severe Respiratory Syncytial Virus Infection Among Infants and Children in Western Countries

INTRODUCTION

The REGAL (RSV [respiratory syncytial virus] Evidence-a Geographical Archive of the Literature) series provides a comprehensive review of the published evidence in the field of RSV in Western countries over the last 20 years. This first of seven publications covers the epidemiology and burden of RSV infection.

METHODS

A systematic review was undertaken for articles published between Jan 1, 1995 and Dec 31, 2015 across PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov. Studies reporting data for hospital visits/admissions for RSV infection among children (≤18 years of age), as well as studies reporting RSV-associated morbidity, mortality, and risk factors were included. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULT

2315 studies were identified of which 98 were included. RSV was associated with 12-63% of all acute respiratory infections (ARIs) and 19-81% of all viral ARIs causing hospitalizations in children (high SOE). Annual RSV hospitalization (RSVH) rates increased with decreasing age and varied by a factor of 2-3 across seasons (high SOE). Studies were conflicting on whether the incidence of RSVH has increased, decreased, or remained stable over the last 20 years (moderate SOE). Length of hospital stay ranged from 2 to 11 days, with 2-12% of cases requiring intensive care unit admission (moderate SOE). Case-fatality rates were <0.5% (moderate SOE). Risk factors associated with RSVH included: male sex; age <6 months; birth during the first half of the RSV season; crowding/siblings; and day-care exposure (high SOE).

CONCLUSION

RSV infection remains a major burden on Western healthcare systems and has been associated with significant morbidity. Further studies focusing on the epidemiology of RSV infection (particularly in the outpatient setting), the impact of co-infection, better estimates of case-fatality rates and associated risk factors (all currently moderate/low SOE) are needed to determine the true burden of disease.

FUNDING

Abbvie.

A randomized trial of nebulized 3% hypertonic saline with salbutamol in the treatment of acute bronchiolitis in hospitalized infants

OBJECTIVE

Acute bronchiolitis is a common disorder of infants that often results in hospitalization. Apart from supportive care, no therapy has been shown to influence the course of the disease, except for a possible effect of nebulized hypertonic saline (HS). To determine whether this does have beneficial effects on length of stay in hospital or on severity scores, we undertook a double-blind, randomized, controlled trial in a pediatric department of a Portuguese hospital.

METHODS

Previously healthy infants, younger than 12 months, hospitalized with mild-to-moderate acute viral bronchiolitis were randomized to receive either nebulized 3% (hypertonic, HS) or 0.9% (normal, NS) saline during their entire hospital stay. Primary endpoints were: length of hospital stay and severity scores on each day of hospitalization. Need for supplemental oxygen, further add-on medications and adverse effects were also analyzed.

RESULTS

Sixty-eight patients completed the study (HS: 33; NS: 35). The median length of hospital stay did not differ between groups: HS: 5.6 ± 2.3 days; NS: 5.4 ± 2.1 days (P = 0.747). We found no difference between groups in severity scores from day 1 to day 4. There were no differences in need for supplemental oxygen or add-on medications. Patients in HS group had significantly more cough (46% vs. 20%, P = 0.025) and rhinorrhoe (58% vs. 31%, P = 0.30).

CONCLUSION

This study does not support the use of nebulized HS over NS in therapy of hospitalized children with mild-to-moderate acute viral bronchiolitis.

Risk of Respiratory Syncytial Virus Infection in Cyanotic Congenital Heart Disease in a Subtropical Area

OBJECTIVE

To compare the risk of respiratory syncytial virus (RSV)-associated hospitalization and analyze the epidemiology of RSV infection in patients with cyanotic and acyanotic congenital heart disease (CHD), we analyzed the nationwide health insurance database from 2005-2010.

STUDY DESIGN

This study included 1050 patients with cyanotic CHD and 7077 patients with acyanotic CHD. Patients with acyanotic CHD were further classified into hemodynamically significant (hs)-acyanotic and non-hs-acyanotic groups according to whether they underwent surgery or took at least 2 anticongestive medications.

RESULTS

RSV-associated hospitalization was higher in the cyanotic group than in hs-acyanotic and non-hs-acyanotic groups both before 1 year of age (4.8% vs 2.1% vs 1.5%, P < .001) and between 1 and 2 years of age (0.9% vs 0.56% vs 0.14%, P = .003). The hospitalization duration, intensive care, ventilator support prevalence, hospitalization cost, and mortality rate were significantly higher in the cyanotic group than in the other 2 groups. Logistic regression revealed that cyanotic CHD was the most significant risk factor for the ventilator support and RSV-associated mortality. In both patients with cyanotic and acyanotic CHD, RSV-associated hospitalization rate was higher in patients aged younger than 1 year and in spring and autumn in Taiwan, a subtropical country.

CONCLUSIONS

The results show that patients with cyanotic CHD have a higher risk of severe RSV infection than do those with acyanotic CHD. RSV prophylaxis is more important and may reduce costs more for patients with cyanotic CHD.

Population-based Analysis of Bronchiolitis Epidemiology in Valencia, Spain

BACKGROUND

There is a lack of European epidemiologic population-based studies on bronchiolitis and respiratory syncytial virus (RSV) bronchiolitis including both hospitalizations and primary care attendance.

METHODS

A retrospective cohort of all children born between 2009 and 2012 was followed from birth to 2 years of age using population and health databases. We searched for global bronchiolitis (International Classification of Diseases, 9th revision, Clinical Modification codes 466.1, 466.11 and 466.19) and RSV bronchiolitis (code 466.11 and code 466.19 with positive RSV test) in the first appearance either in primary care or in hospitalization databases. A preterm subcohort (International Classification of Diseases, 9th revision, Clinical Modification codes 765) was also analyzed.

RESULTS

The cohort consisted of 198,223 children of whom 41,479 were diagnosed of bronchiolitis (incidence rate 16.4/100 children <2 years per year). Of those, 5390 were hospitalized with the majority of hospitalizations occurring at <6 months of age (incidence rate of 5.2/100 children <6 months per year) and 3106 of the hospitalizations were RSV positive (incidence rate 3.2/100 children <6 months per year). RSV hospitalizations were 26% longer than non-RSV. In preterm infants, hospitalization incidence was more than double, and the mean length of hospitalization was 29% longer.

CONCLUSIONS

Most (87%) bronchiolitis cases are managed in primary care offices. Approximately 2 out of every 10 children <2 are diagnosed of bronchiolitis, 3 out of every 100 are hospitalized and 1.6 out of every 100 are hospitalized with RSV bronchiolitis in our cohort. Infants between 2 and 10 weeks constitute a risk group for severe bronchiolitis.

Trends in respiratory syncytial virus bronchiolitis hospitalizations in children less than 1 year: 2004-2012

OBJECTIVE

To analyze trends in health outcomes and the influence of risk factors in children under 1 year with acute bronchiolitis due to respiratory syncytial virus (RSV bronchiolitis). A risk-adjustment model for RSV bronchiolitis in-hospital mortality was also developed.

RESEARCH DESIGN AND METHODS

Retrospective study of hospitalizations for RSV bronchiolitis in children aged <1 year from 2004 to 2012. We used nationally representative data from the Spanish National Health Service records.

RESULTS

Over the study period, the annual hospital discharges for RSV bronchiolitis ranged between 6390 and 8637. The annual in-hospital mortality rate ranged from 120 (2004) to 69 (2012) per 100,000 hospitalizations and the mean length of stay decreased steadily from 6.5 to 5.2 days (p < 0.001); 98.3% of hospitalizations for RSV bronchiolitis were children without risk factors. The in-hospital mortality rate due to RSV bronchiolitis in children with risk factors was 18.8 times higher than non-high-risk children and, in adjusted analyses, the OR of in-hospital mortality due to RSV bronchiolitis was higher than that due to other causes.

LIMITATIONS

This study is a retrospective analysis, based on administrative data. It does not include data about pre- or in-hospital treatments, and has the limitations inherent in procedures for determining risk-adjusted mortality rates. Socioeconomic and environmental factors have not been considered in this study.

CONCLUSIONS

RSV bronchiolitis is a leading cause of hospitalizations for infants under 1 year and has not shown incidence reduction over a 9 year period. Risk factors increase the in-hospital mortality risk and it is higher if the hospitalization cause is RSV bronchiolitis than any other reason.

Blood eosinophilia is associated with unfavorable hospitalization outcomes in children with bronchiolitis

BACKGROUND

Bronchiolitis, the most common indication for hospitalization of young children, is associated with subsequent asthma. Blood eosinophilia is associated with increased severity of asthma, but it is unclear if eosinophilia is associated with severity of illness in bronchiolitis. We hypothesized that blood eosinophilia is associated with unfavorable short-term outcomes of bronchiolitis hospitalizations.

METHODS

Data from initial bronchiolitis admissions to our institution between 2010 and 2013 were extracted using Population Explorer software (Explorys, Cleveland, OH). Children were categorized as "CBC-none" (no complete blood count [CBC] data during the first 7 days of hospitalization), EOS-positive (at least one CBC with ≥300 eosinophils per microliter or ≥3% of all leukocytes identified as eosinophils) or EOS-negative (at least one CBC and no eosinophilia). The association between hospitalization duration and maximum absolute eosinophil count (AEC) was analyzed using Spearman correlation. Variables independently associated with prolonged (≥72 hr) hospitalization were identified using stepwise multivariate logistic regression.

RESULTS

In 1356 inpatients <24 months with bronchiolitis, median hospitalization duration was 2.46 days and 38.0% had prolonged hospitalization. CBC data were available in 32.4% of subjects: 20.7% were EOS-positive and 79.3% were EOS-negative. Increased maximum AEC was significantly associated with longer duration of hospitalization. Prolonged hospitalization was independently associated with EOS-positive versus EOS-negative children (OR 1.88, 95%CI: 1.12-3.17, P = 0.020). Mechanical ventilation was most common in EOS-positive subjects (24.2% of cases), versus EOS-negative (7.2%) and CBC-none (0.7%) (P < 0.001).

CONCLUSIONS

Blood eosinophilia is associated with unfavorable clinical outcomes in a large cohort of inpatients with bronchiolitis.

Decreased Incidence of Respiratory Infections in Children After Vaccination with Ten-valent Pneumococcal Vaccine

INTRODUCTION

Respiratory tract infections (RTIs) and antibiotic usage are common in children, increasing the risk of antibacterial resistance. The introduction of protein-conjugated pneumococcal vaccines has led to reduction in pneumococcal infections. In 2011, pneumococcal protein-conjugated vaccine-10 was introduced into the national childhood vaccination in Iceland, a population not earlier vaccinated against pneumococcus, with 95% vaccine uptake in the first year. The aim of the study was to evaluate the number of children visiting the Children's Hospital Iceland for RTIs before and after the introduction of the vaccine.

METHODS

Admissions and visits to the Children's Hospital because of RTIs were recorded, and children aged 3 months to 2 years in the nonvaccine eligible cohort (born 2008-2010) were compared with the vaccine eligible cohort (born in 2011). Statistical analysis was done using large sample Z test and incidence rate ratios (IRRs) were calculated.

RESULTS

A significant reduction in incidence rate was found when comparing the nonvaccine eligible cohort with the vaccine eligible cohort, both for acute otitis media (AOM) (IRR: 0.76; 95% confidence interval: 0.67-0.87; P < 0.0001) and for pneumonia (IRR: 0.77; 95% confidence interval: 0.64-0.95; P < 0.01).

CONCLUSION

A significant reduction in hospital visits because of AOM and pneumonia in children vaccinated with pneumococcal protein-conjugated vaccine-10 was established. The abrupt and significant reduction of AOM is unusually clear. This reduction was noted very early after initiation of the vaccination.

The role of Th17 and Treg responses in the pathogenesis of RSV infection

The respiratory syncytial virus (RSV) represents the leading cause of viral bronchiolitis and pneumonia in children worldwide and is associated with high morbidity, hospitalization rate, and significant mortality rates. The immune response elicited by RSV is one of the main factors contributing to the pathogenesis of the disease. Two subsets of the cellular immune response, the T helper 17 cell (Th17) and the regulatory T-cell (Treg), and more particularly the balance between these two subsets, might play a significant role in the pathogenesis of the RSV infection. The developmental pathways of Th17 and Treg cells are closely and reciprocally interconnected and plasticity has been demonstrated from Treg toward Th17. During an RSV infection, the functions of both subsets are opposed to one another regarding viral clearance and clinical severity. Th17 and Treg cells offer a promising new view on the pathogenesis of an RSV infection and deserve further exploration.

Virus Type and Genomic Load in Acute Bronchiolitis: Severity and Treatment Response With Inhaled Adrenaline

Background. Acute bronchiolitis frequently causes infant hospitalization. Studies on different viruses or viral genomic load and disease severity or treatment effect have had conflicting results. We aimed to investigate whether the presence or concentration of individual or multiple viruses were associated with disease severity in acute bronchiolitis and to evaluate whether detected viruses modified the response to inhaled racemic adrenaline.

Methods. Nasopharyngeal aspirates were collected from 363 infants with acute bronchiolitis in a randomized, controlled trial that compared inhaled racemic adrenaline versus saline. Virus genome was identified and quantified by polymerase chain reaction analyses. Severity was assessed on the basis of the length of stay and the use of supportive care.

Results. Respiratory syncytial virus (83%) and human rhinovirus (34%) were most commonly detected. Seven other viruses were present in 8%–15% of the patients. Two or more viruses (maximum, 7) were detected in 61% of the infants. Virus type or coinfection was not associated with disease severity. A high genomic load of respiratory syncytial virus was associated with a longer length of stay and with an increased frequency of oxygen and ventilatory support use. Treatment effect of inhaled adrenaline was not modified by virus type, load or coinfection.

Discussion. In infants hospitalized with acute bronchiolitis, disease severity was not associated with specific viruses or the total number of viruses detected. A high RSV genomic load was associated with more-severe disease.

Clinical Trials Registration. NCT00817466 and EudraCT 2009-012667-34.

Immunostimulatory Defective Viral Genomes from Respiratory Syncytial Virus Promote a Strong Innate Antiviral Response during Infection in Mice and Humans

Human respiratory syncytial virus (RSV) is a major cause of severe respiratory illness in children and susceptible adults. RSV blocks the development of the innate antiviral immune response and can grow to high titers in the respiratory tract. Here we demonstrate that immunostimulatory defective viral genomes (iDVGs) that are naturally generated during RSV replication are strong inducers of the innate antiviral response to RSV in mice and humans. In mice, RSV iDVGs stimulated the expression of antiviral genes, restricted viral replication, and prevented weight loss and lung inflammation. In human cells, the antiviral response to RSV iDVGs was dominated by the expression of IFN-λ1 over IFN-β and was driven by rapid intranuclear accumulation of the transcription factor IRF1. RSV iDVGs were detected in respiratory secretions of hospitalized patients, and their amount positively correlated with the level of expression of antiviral genes in the samples. Infection of explanted human lung tissue from different donors revealed that most humans can respond to RSV iDVGs and that the rate of accumulation of iDVGs during infection directly correlates with the quality of the antiviral response. Taken together, our data establish iDVGs as primary triggers of robust antiviral responses to RSV and provide the first evidence for an important biological role for naturally occurring iDVGs during a paramyxovirus infection in humans.

Neutrophils in respiratory syncytial virus infection: A target for asthma prevention

Lower respiratory tract infections by respiratory syncytial virus (RSV) are the foremost cause of infant hospitalization and are implicated in lasting pulmonary impairment and the development of asthma. Neutrophils infiltrate the airways of pediatric patients with RSV-induced bronchiolitis in vast numbers: approximately 80% of infiltrated cells are neutrophils. However, why neutrophils are recruited to the site of viral respiratory tract infection is not clear. In this review we discuss the beneficial and pathologic contributions of neutrophils to the immune response against RSV infection. Neutrophils can limit viral replication and spread, as well as stimulate an effective antiviral adaptive immune response. However, low specificity of neutrophil antimicrobial armaments allows for collateral tissue damage. Neutrophil-induced injury to the airways during the delicate period of infant lung development has lasting adverse consequences for pulmonary architecture and might promote the onset of asthma in susceptible subjects. We suggest that pharmacologic modulation of neutrophils should be explored as a viable future therapy for severe RSV-induced bronchiolitis and thereby prevent the inception of subsequent asthma. The antiviral functions of neutrophils suggest that targeting of neutrophils in patients with RSV-induced bronchiolitis is best performed under the umbrella of antiviral treatment.

Epidemiological Features of Bronchiolitis in the Pediatric Clinic of Clinical center of Sarajevo University

OBJECTIVE

To present the epidemiological features of bronchiolitis in a one-year period in patients of Pediatric Clinic, Clinical Centre of Sarajevo University.

INTRODUCTION

Bronchiolitis is the most common respiratory infection of early infant age. The disease is one the most common reason for hospitalization of children under the age of six months. The disease is characterized by occurrences in the winter season November-March. For daily diagnosing of severe forms of bronchiolitis as a clinical syndrome, often sufficient are the knowledge of the epidemiological data, age of the patient, clinical examination and insight into the risk factors.

PATIENTS AND METHODS

The history of the disease in 155 infant patients, who were clinically treated because of bronchiolitis in the period from February 2013 to February 2014 in the Department of Pediatric Pulmonary Clinic in Sarajevo was retrospectively analyzed.

RESULTS

The majority of patients were aged less than 6 months (87.7%). The monthly distribution of bronchiolitis had a peak in January and February. Almost 50% of patients had a risk factors for the development of severe forms of bronchiolitis out of which the most common were artificial diet (53.5%), low birth weight below 2500g (17%), prematurity (16.1%), congenital heart anomalies (14.2%), bronchopulmonary dysplasia (1.9%). 46,5% of patients were on natural nutrition. 46 patients (29.6%) were serologically or by respi-strip test in nasopharyngeal lavage positive on respiratory syncytial virus (RSV). There were no patients who required mechanical ventilation.

CONCLUSION

During the one-year period, bronchiolitis was the most common diagnose in the early infantile period up to 6 months, with a peak incidence in January and February. Risk factors such as prematurity, low birth weight, congenital heart anomalies and bronchopulmonary dysplasia have been less present in the studied period compared to the period before the introduction of RSV chemoprophylaxis. The epidemiological data obtained have facilitated the diagnosis, and accordingly the timely and appropriate treatment of bronchiolitis.

Respiratory Syncytial Virus Bronchiolitis in Children up to 5 Years of Age in Spain: Epidemiology and Comorbidities: An Observational Study

This epidemiological survey in Spain estimates the burden of respiratory syncytial virus (RSV) infection in children up to 5 year of age during a 15-year period (1997-2011). Observational retrospective survey was conducted by reviewing data of the National Surveillance System for Hospital Data, including >98% of Spanish hospitals. All hospitalizations related to RSV infection for children up to 5 years, reported during 1997-2011 period, were analyzed. Codes were selected by using the International Classification of Diseases 9th Clinical Modification 466.0-466.19, 480.1, and 079.6. A total of 326,175 and 286,007 hospital discharges for children up to 5 and 2 years of age were reported during the study period. The annual incidence was 1072 and 2413 patients per 100,000, respectively. The average length of hospital stay was 5.7 (standard deviation 8.2) days. Four hundred forty-six deaths were reported; of those, 403 occurred in children <2 years and 355 (80%) occurred in children <12 months of age. Hospitalization and mortality rates were significantly higher in boys and decrease significantly with age. The higher rate of hospitalization and mortality rates were found in the first year of life. Annual average cost for National Health Care System was € 47 M with a mean hospitalization cost of €2162. The average length of hospitalization and costs were significantly higher in high-risk children. RSV infections in children up to 5 year of age still pose a significant health threat in Spain, especially in the infants. The development of preventive, diagnostic, and therapeutic guidelines focused in children with comorbidities may help reduce the hospital and economic burden of the disease.

Leukotriene inhibitors for bronchiolitis in infants and young children

BACKGROUND

Bronchiolitis is an acute inflammatory illness of the bronchioles common among infants and young children. It is often caused by the respiratory syncytial virus (RSV). Management of bronchiolitis varies between clinicians, reflecting the lack of evidence for a specific treatment approach. The leukotriene pathway has been reported to be involved in the pathogenesis of bronchiolitis. Leukotriene inhibitors such as montelukast have been used in infants and young children with bronchiolitis. However, the results from limited randomised controlled trials (RCTs) are controversial and necessitate a thorough evaluation of their efficacy for bronchiolitis in infants and young children.

OBJECTIVES

To assess the efficacy and safety of leukotriene inhibitors for bronchiolitis in infants and young children.

SEARCH METHODS

We searched CENTRAL (2014, Issue 5), MEDLINE (1946 to April week 4, 2014), EMBASE (1974 to May 2014), CINAHL (1981 to May 2014), LILACS (1982 to May 2014), Web of Science (1985 to May 2014), WHO ICTRP and ClinicalTrials.gov (6 May 2014).

SELECTION CRITERIA

RCTs comparing leukotriene inhibitors versus placebo or another intervention in infants and young children under two years of age diagnosed with bronchiolitis. Our primary outcomes were length of hospital stay and all-cause mortality. Secondary outcomes included clinical severity score, percentage of symptom-free days, percentage of children requiring ventilation, oxygen saturation, recurrent wheezing, respiratory rate and clinical adverse effects.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Collaboration methodological practices. Two authors independently assessed trial eligibility and extracted data, such as general information, participant characteristics, interventions and outcomes. We assessed risk of bias and graded the quality of the evidence. We used Review Manager software to pool results and chose random-effects models for meta-analysis.

MAIN RESULTS

We included five studies with a total of 1296 participants under two years of age hospitalised with bronchiolitis. Two studies with low risk of bias compared 4 mg montelukast (a leukotriene inhibitor) daily use from admission until discharge with a matching placebo. Both selected length of hospital stay as a primary outcome and clinical severity score as a secondary outcome. However, the effects of leukotriene inhibitors on length of hospital stay and clinical severity score were uncertain due to considerable heterogeneity between the study results and wide confidence intervals around the estimated effects (hospital stay: mean difference (MD) -0.95 days, 95% confidence interval (CI) -3.08 to 1.19, P value = 0.38, low quality evidence; clinical severity score on day two: MD -0.57, 95% CI -2.37 to 1.23, P value = 0.53, low quality evidence; clinical severity score on day three: MD 0.17, 95% CI -1.93 to 2.28, P value = 0.87, low quality evidence). The other three studies compared montelukast for several weeks for preventing post-bronchiolitis symptoms with placebo. We assessed one study as low risk of bias, whereas we assessed the other two studies as having a high risk of attrition bias. Due to the significant clinical heterogeneity in severity of disease, duration of treatment, outcome measurements and timing of assessment, we did not pool the results. Individual analyses of these studies did not show significant differences between the leukotriene inhibitors group and the control group in symptom-free days and incidence of recurrent wheezing. One study of 952 children reported two deaths in the leukotriene inhibitors group: neither was determined to be drug-related. No data were available on the percentage of children requiring ventilation, oxygen saturation and respiratory rate. Finally, three studies reported adverse events including diarrhoea, wheezing shortly after administration and rash. No differences were reported between the study groups.

AUTHORS' CONCLUSIONS

The current evidence does not allow definitive conclusions to be made about the effects of leukotriene inhibitors on length of hospital stay and clinical severity score in infants and young children with bronchiolitis. The quality of the evidence was low due to inconsistency (unexplained high levels of statistical heterogeneity) and imprecision arising from small sample sizes and wide confidence intervals, which did not rule out a null effect or harm. Data on symptom-free days and incidence of recurrent wheezing were from single studies only. Further large studies are required. We identified one registered ongoing study, which may make a contribution in the updates of this review.

Hospitalisation costs for infant bronchiolitis are up to 20 times higher if intensive care is needed

AIM

Up to 3% of infants with bronchiolitis under 12 months of age are hospitalised, and up to 9% require intensive care. We evaluated the costs of bronchiolitis hospitalisation, with a special focus on whether infants needed intensive care.

METHODS

Baseline and cost data were retrospectively collected, using electronic hospital files, for 80 infants under 12 months old who were treated in the paediatric intensive care unit (PICU) for bronchiolitis during a 13-year period. We calculated the daily costs for patients admitted to the PICU and compared them with 104 admitted to inpatient wards and 56 outpatients treated in the emergency department.

RESULTS

The mean hospitalisation cost for PICU patients was €8061 (95% CI 6193-9929), compared to €1834 (1649-2020) for other inpatients and €359 (331-387) for the outpatients. The hospitalisation cost per patient was associated with length of hospital stay, but not gender, age on admission or gestational age. There was no constant increase or decrease in hospitalisation costs during the study period.

CONCLUSION

The hospitalisation costs of infants treated in the PICU for bronchiolitis at <12 months of age were approximately four times more than for other inpatients and over 20 times more than for outpatients. Strategies are needed to reduce the need for intensive care.

Respiratory syncytial virus (RSV) and its propensity for causing bronchiolitis

Infants and young children with acute onset of wheezing and reduced respiratory airflows are often diagnosed with obstruction and inflammation of the small bronchiolar airways, ie bronchiolitis. The most common aetological agents causing bronchiolitis in young children are the respiratory viruses, and of the commonly encountered respiratory viruses, respiratory syncytial virus (RSV) has a propensity for causing bronchiolitis. Indeed, RSV bronchiolitis remains the major reason why previously healthy infants are admitted to hospital. Why RSV infection is such a predominant cause of bronchiolitis is the subject of this review. By reviewing the available histopathology of RSV bronchiolitis, both in humans and relevant animal models, we identify hallmark features of RSV infection of the distal airways and focus attention on the consequences of columnar cell cytopathology occurring in the bronchioles, which directly impacts the development of bronchiolar obstruction, inflammation and disease. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Bronchiolitis associated with Mycoplasma pneumoniae in infants in Suzhou China between 2010 and 2012

Viruses cause most cases of bronchiolitis in infants; consequently the importance of other agents such as Mycoplasma pneumoniae (MP) in the etiology of bronchiolitis may not be fully recognized. We investigated the prevalence and seasonal distribution of bronchiolitis caused by MP in 674 children admitted to the Children's Hospital affiliated with Soochow University from January 2010 to December 2012. The presence of MP was confirmed by real-time PCR. During the 3 years, we identified MP in 17.2% of the children with bronchiolitis. The annual MP detection rates were 16.6% in 2010, 17.8% in 2011, and 17.2% in 2012. MP was detected throughout the year, with a peak from July to September. The median age of MP-positive children was 10 months. Common clinical manifestations included cough, wheezing, and high fever. Moist and/or wheezing rales were frequent, and pulmonary interstitial infiltration was seen in 66.4% of chest X-rays. Patients with MP infection were older, were more likely to have pulmonary interstitial infiltration, and had shorter hospital stays than those with respiratory syncytial virus infection. Our study revealed MP as an important cause of bronchiolitis, with peaks of occurrence during the summer and early autumn. Pulmonary interstitial infiltrations were a common event.

Virologic testing in bronchiolitis: does it change management decisions and predict outcomes?

The aim of this study was to evaluate the clinical, therapeutic, laboratory, and radiological differences between respiratory syncytial virus (RSV) and non-RSV bronchiolitis in order to assess if the prior knowledge of viral etiology changed management decisions and would be able to predict outcomes. Medical charts of children <1 year admitted to the emergency department with bronchiolitis during two RSV seasons (2010-2012) were reviewed. We analyzed 221 episodes of bronchiolitis. The percentage of exams performed (95 % confidence interval (CI) 0.74-2.52), abnormal laboratory and radiological findings (95 % CI 0.53-16.89) did not differ between groups. RSV bronchiolitis had a more severe clinical course. However, virologic testing for RSV had low specificity in identifying at-risk patients for hospitalization, longer hospital length of stay, and need of oxygen therapy and nasogastric tube (44, 40, 42, and 35 %, respectively), and while statistically significant, the positive likelihood ratios were only slightly greater than 1.

CONCLUSION

Although RSV bronchiolitis has a more severe clinical course, virologic testing does not help in management decisions, and at an individual level, as a performance test, it seems insufficient to precisely predict outcomes.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Surfactant deficiency in infants with severe acute viral bronchiolitis

OBJECTIVES

To evaluate surfactant content and function through the lamellar body count (LBC) and stable microbubble test (SMT) in mechanically ventilated infants with severe acute viral bronchiolitis.

STUDY DESIGN

Controlled cross-sectional study of 32 infants receiving mechanical ventilation: 16 with a diagnosis of acute viral bronchiolitis and 16 with normal lungs. Tracheal fluid was collected and LBC was performed in an automated cell counter. Samples were kept frozen and thawed for testing. At the time of analysis, samples were diluted in a dithiothreitol solution, vortexed for 10 seconds, and aspirated by the cell counter. SMT was performed using the Pattle technique.

RESULTS

In the bronchiolitis group, the median (IQR) LBC was significantly lower than in the control group: 130,000 (61,250-362,250) vs. 518,000 (180,250-896,000) lamellar bodies/μL; P = .003. Median (IQR) SMT values were also significantly lower in the bronchiolitis group: 10 (2-13) vs. 400 (261-615) microbubbles/mm2; P < .001.

CONCLUSIONS

Infants with acute viral bronchiolitis have reduced surfactant content and function. We speculate that these simple tests may be useful to identify infants with bronchiolitis who would benefit from surfactant replacement therapy.

RSV-encoded NS2 promotes epithelial cell shedding and distal airway obstruction

Respiratory syncytial virus (RSV) infection is the major cause of bronchiolitis in young children. The factors that contribute to the increased propensity of RSV-induced distal airway disease compared with other commonly encountered respiratory viruses remain unclear. Here, we identified the RSV-encoded nonstructural 2 (NS2) protein as a viral genetic determinant for initiating RSV-induced distal airway obstruction. Infection of human cartilaginous airway epithelium (HAE) and a hamster model of disease with recombinant respiratory viruses revealed that NS2 promotes shedding of infected epithelial cells, resulting in two consequences of virus infection. First, epithelial cell shedding accelerated the reduction of virus titers, presumably by clearing virus-infected cells from airway mucosa. Second, epithelial cells shedding into the narrow-diameter bronchiolar airway lumens resulted in rapid accumulation of detached, pleomorphic epithelial cells, leading to acute distal airway obstruction. Together, these data indicate that RSV infection of the airway epithelium, via the action of NS2, promotes epithelial cell shedding, which not only accelerates viral clearance but also contributes to acute obstruction of the distal airways. Our results identify RSV NS2 as a contributing factor for the enhanced propensity of RSV to cause severe airway disease in young children and suggest NS2 as a potential therapeutic target for reducing the severity of distal airway disease.

Epidemiological and clinical data of hospitalizations associated with respiratory syncytial virus infection in children under 5 years of age in Spain: FIVE multicenter study

BACKGROUND

Respiratory syncytial virus (RSV) is an important pathogen in lower respiratory tract infections (LRTI) in infants, but there are limited data concerning patients with underlying conditions and children older than 2 years of age.

METHODS

We have designed a prospective observational multicenter national study performed in 26 Spanish hospitals (December 2011-March 2012). Investigational cases were defined as children with underlying chronic diseases and were compared with a group of previously healthy children (proportion 1:2). Clinical data were compared between the groups.

RESULTS

A total of 1763 children hospitalized due to RSV infection during the inclusion period were analyzed. Of them, 225 cases and 460 healthy children were enrolled in the study. Underlying diseases observed were respiratory (64%), cardiovascular (25%), and neurologic (12%), as well as chromosomal abnormalities (7·5%), immunodeficiencies (6·7%), and inborn errors of metabolism (3·5%). Cases were statistically older than previously healthy children (average age: 16·3 versus 5·5 months). Cases experienced hypoxemia more frequently (P < 0·001), but patients with respiratory diseases required oxygen therapy more often (OR: 2·99; 95% CI: 1·03-8·65). Mechanical ventilation was used more in patients with cardiac diseases (OR: 3·0; 95% CI: 1·07-8·44) and in those with inborn errors of metabolism (OR: 12·27; 95% CI: 2·11-71·47). This subgroup showed a higher risk of admission to the PICU (OR: 6·7, 95% CI: 1·18-38·04). Diagnosis of pneumonia was more frequently found in cases (18·2% versus 9·3%; P < 0·01).

CONCLUSIONS

A significant percentage of children with RSV infection have underlying diseases and the illness severity is higher than in healthy children.

Predictors of severity and mortality in children hospitalized with respiratory syncytial virus infection in a tropical region

INTRODUCTION

Respiratory syncytial virus (RSV) is one of the leading causes of acute lower respiratory infection (ALRI) in infants and young children. Although ALRI is a major public health problem in developing countries located in tropical areas, studies about RSV epidemiology in these regions are scarce.

METHODS

In a retrospective cohort study, we investigated the epidemiology and predictive variables that reflect disease severity and mortality in young children hospitalized with ALRI due to RSV in Colombia, South-America, during a 2-year period (2009-2011).

RESULTS

Of a total of 6,344 children with a diagnosis of ALRI, we selected 2,147 (33.8%) that were positive for RSV. After controlling for pre-existing conditions, we found that independent predictors of severe disease in our population included age <6 months (RR 2.01; CI 95% 1.70-2.38; P < 0.001), prematurity (RR 1.61; CI 95% 1.20-2.17; P = 0.001), congenital heart disease (RR 2.03; CI 95% 1.16-3.54; P = 0.013), and mixed RSV-adenovirus infection (RR 2.09; CI 95% 1.60-2.73; P < 0.001). Multivariate analysis identified that cancer (RR 31.60; CI 95% 5.97-167.13; P < 0.001) is a predictor of mortality in our RSV-infected pediatric population independently of age and other co-morbidities.

CONCLUSIONS

RSV is an important cause of ALRI in infants and young children living in tropical regions, especially during the rainy season. The identified predictors of severe disease and mortality should be taken into account when planning interventions to reduce the burden of ALRI in young children living in these regions.

Mortality attributable to influenza in England and Wales prior to, during and after the 2009 pandemic

Very different influenza seasons have been observed from 2008/09-2011/12 in England and Wales, with the reported burden varying overall and by age group. The objective of this study was to estimate the impact of influenza on all-cause and cause-specific mortality during this period. Age-specific generalised linear regression models fitted with an identity link were developed, modelling weekly influenza activity through multiplying clinical influenza-like illness consultation rates with proportion of samples positive for influenza A or B. To adjust for confounding factors, a similar activity indicator was calculated for Respiratory Syncytial Virus. Extreme temperature and seasonal trend were controlled for. Following a severe influenza season in 2008/09 in 65+yr olds (estimated excess of 13,058 influenza A all-cause deaths), attributed all-cause mortality was not significant during the 2009 pandemic in this age group and comparatively low levels of influenza A mortality were seen in post-pandemic seasons. The age shift of the burden of seasonal influenza from the elderly to young adults during the pandemic continued into 2010/11; a comparatively larger impact was seen with the same circulating A(H1N1)pdm09 strain, with the burden of influenza A all-cause excess mortality in 15-64 yr olds the largest reported during 2008/09-2011/12 (436 deaths in 15-44 yr olds and 1,274 in 45-64 yr olds). On average, 76% of seasonal influenza A all-age attributable deaths had a cardiovascular or respiratory cause recorded (average of 5,849 influenza A deaths per season), with nearly a quarter reported for other causes (average of 1,770 influenza A deaths per season), highlighting the importance of all-cause as well as cause-specific estimates. No significant influenza B attributable mortality was detected by season, cause or age group. This analysis forms part of the preparatory work to establish a routine mortality monitoring system ahead of introduction of the UK universal childhood seasonal influenza vaccination programme in 2013/14.

Respiratory syncytial virus--a comprehensive review

Respiratory syncytial virus (RSV) is amongst the most important pathogenic infections of childhood and is associated with significant morbidity and mortality. Although there have been extensive studies of epidemiology, clinical manifestations, diagnostic techniques, animal models and the immunobiology of infection, there is not yet a convincing and safe vaccine available. The major histopathologic characteristics of RSV infection are acute bronchiolitis, mucosal and submucosal edema, and luminal occlusion by cellular debris of sloughed epithelial cells mixed with macrophages, strands of fibrin, and some mucin. There is a single RSV serotype with two major antigenic subgroups, A and B. Strains of both subtypes often co-circulate, but usually one subtype predominates. In temperate climates, RSV infections reflect a distinct seasonality with onset in late fall or early winter. It is believed that most children will experience at least one RSV infection by the age of 2 years. There are several key animal models of RSV. These include a model in mice and, more importantly, a bovine model; the latter reflects distinct similarity to the human disease. Importantly, the prevalence of asthma is significantly higher amongst children who are hospitalized with RSV in infancy or early childhood. However, there have been only limited investigations of candidate genes that have the potential to explain this increase in susceptibility. An atopic predisposition appears to predispose to subsequent development of asthma and it is likely that subsequent development of asthma is secondary to the pathogenic inflammatory response involving cytokines, chemokines and their cognate receptors. Numerous approaches to the development of RSV vaccines are being evaluated, as are the use of newer antiviral agents to mitigate disease. There is also significant attention being placed on the potential impact of co-infection and defining the natural history of RSV. Clearly, more research is required to define the relationships between RSV bronchiolitis, other viral induced inflammatory responses, and asthma.

Epidemiological and genetic characteristics associated with the severity of acute viral bronchiolitis by respiratory syncytial virus

OBJECTIVE

to assess the epidemiological and genetic factors associated with severity of acute viral bronchiolitis (AVB) by respiratory syncytial virus (RSV).

DATA SOURCE

the key words "bronchiolitis", "risk factor", "genetics" and "respiratory syncytial virus", and all combinations among them were used to perform a search in the PubMed, SciELO, and Lilacs databases, of articles published after the year 2000 that included individuals younger than 2 years of age.

DATA SYNTHESIS

a total of 1,259 articles were found, and their respective summaries were read. Of these, 81 were selected, which assessed risk factors for the severity of AVB, and were read in full; the 60 most relevant studies were included. The epidemiologic factors associated with AVB severity by RSV were prematurity, passive smoking, young age, lack of breastfeeding, chronic lung disease, congenital heart disease, male gender, ethnicity, viral coinfection, low weight at admission, maternal smoking during pregnancy, atopic dermatitis, mechanical ventilation in the neonatal period, maternal history of atopy and/or asthma during pregnancy, season of birth, low socioeconomic status, Down syndrome, environmental pollution, living at an altitude > 2,500 meters above sea level, and cesarean section birth. Conversely, some children with severe AVB did not present any of these risk factors. In this regard, recent studies have verified the influence of genetic factors on the severity of AVB by RSV. Polymorphisms of the TLRs, RANTES, JUN, IFNA5, NOS2, CX3CR1, ILs, and VDR genes have been shown to be associated with more severe evolution of AVB by RSV.

CONCLUSION

the severity of AVB by RSV is a phenomenon that depends on the varying degrees of interaction among epidemiological, environmental, and genetic variables.

Respiratory syncytial virus infections in infants and children with congenital heart disease: update on the evidence of prevention with palivizumab

PURPOSE OF REVIEW

Lower respiratory tract infections multiply morbidity and mortality within patients with significant congenital heart disease (CHD). For respiratory syncytial virus (RSV), one of the most important pathogens, immunoprophylaxis with palivizumab has successfully been introduced. The question is which patients will benefit most from this costly preventive treatment.

RECENT FINDINGS

The era after the introduction of palivizumab has revealed a steep decrease in mortality. The markers of success - hospital stays, admission to the intensive care unit, days on mechanical ventilation, and death - consistently favor immunoprophylaxis. The key point of treatment success remains in all cases a careful patient selection, adherence to a time limit of 30 days between the injections and early use after cardiac surgery with cardiopulmonary bypass, as well as avoidance of nosocomial-acquired infections. Preventive therapy with palivizumab in patients with CHD has been investigated in terms of operating efficiency - with the lowest costs per quality-adjusted life years compared with preterm infants with or without bronchopulmonary dysplasia.

SUMMARY

The burden of RSV disease will decline, once a vaccine is available. Meanwhile, immunoprophylaxis with palivizumab is a useful tool for high-risk patients to reduce comorbidity and fatal outcome. Pharmacoeconomic considerations measuring quality-adjusted life years indicate important information about cost-effectiveness.