Risk Factors For Severe Bronchiolitis Research Articles

Does weight influence the course of RSV bronchiolitis in hospitalized infants?

Acute bronchiolitis is among the most common causes of hospitalizations in infants worldwide. Associations between weight and severity of respiratory syncytial virus (RSV) bronchiolitis remain unclear. The aim of this study was to evaluate this association. A single-center, retrospective cohort study of infants aged under 24 months, who were hospitalized between 2018 and 2022 for RSV bronchiolitis. Data from computerized medical records were extracted using the MDclone platform. Participants were divided into three groups according to weight percentiles: underweight (below 5th percentile), normal-weight, and overweight (above 85th percentile). A total of 1936 infants (mean age 6.3 months, 55% males) were included, comprising 274 infants who were underweight, 1470 with normal weight, and 192 with overweight. Underweight infants had a higher rate of admission to the pediatric intensive care unit (PICU) (9.1% vs. 3.5%, P < 0.005) and prolonged length of stay (LOS) in the hospital (3.13 vs. 2.79 days P < 0.001) compared to those with normal weight. Hyponatremia was also more common in the underweight group (23% vs. 15%, P < 0.001). A multivariable model accounting for prematurity and birthweight predicted a relative risk of 2.01 (95% CI 1.13-3.48, P = 0.015) for PICU admission and 1.42 (95% CI 1.17-1.7, P < 0.001) for a prolonged LOS. Being overweight was not associated with a more severe disease. Conclusion: Underweight infants, hospitalized for RSV bronchiolitis, had a more severe disease course with a higher complication rate, including PICU admission and prolonged LOS. Thus, careful attention and supervision should be given to this subgroup of infants. What is Known: • Established risk factors for severe bronchiolitis include prematurity, BPD, CHD, and compromised immunity. • Abnormal weight status has been associated with an increased risk for morbidity and mortality from infectious diseases, proposedly due to the effects on endocrine and immunologic systems. What is New: • Underweight infants hospitalized with RSV bronchiolitis face an independent risk of PICU admission and prolonged hospital stay. • Conversely, overweight infants did not display associations with severity measures in our study.

Overweight Infants Hospitalized for Bronchiolitis Associated With Severe Disease.

Overweight negatively affects pediatric respiratory function. In this study, we evaluate if overweight is associated with more severe bronchiolitis in hospitalized infants. This retrospective cohort study analyzed infants aged 30 to 365 days hospitalized for bronchiolitis from September 2019 to April 2020. Exclusion criteria included known risk factors for severe bronchiolitis, asthma treatment, or bacterial pneumonia. Weight-for-length z-score was categorized per the World Health Organization's growth assessments as overweight (z-score >2), underweight (z-score <-2), and standard weight (between -2 and ≤2). Primary outcomes included respiratory support, ICU stay, and local bronchiolitis score. Secondary outcomes included supplemental interventions. After exclusion criteria, 385 of 644 infants were categorized as overweight (n = 24), standard (n = 335), or underweight (n = 26). There were differences in need for respiratory support (overweight, 100%; standard weight, 81.8%; underweight, 76.9%; P = .03), highest support of high-flow nasal cannula (overweight, 75%; standard weight, 48%; underweight, 42%; P = .03), admission to ICU (overweight, 54.2%; standard weight, 21.5%; underweight, 34.7%; P < .001), and median bronchiolitis score (overweight, 8 [interquartile range 5-10]; standard weight, 4 [3-7]; underweight, 4 [3-7]; P = .01). Findings remained significant after age adjustments. Additionally, overweight experienced higher frequency of certain treatments. This study suggests overweight is associated with more severe bronchiolitis in hospitalized infants supported by increased respiratory support level, bronchiolitis scores, and interventions. Higher need for ICU admission may be related to high-flow nasal cannula limitations on the acute care floor.

Clinical Epidemiological Characteristics and Risk Factors for Severe Bronchiolitis Caused by Respiratory Syncytial Virus in Vietnamese Children.

Introduction Bronchiolitis is the most prevalent cause of hospitalization in infants under the age of 12 months. The disease is caused by respiratory syncytial virus (RSV) infection, which can cause breathing difficulties and respiratory failure. Therefore, it is necessary to discover the risk factors of severe bronchiolitis to diagnose and treat promptly. This study is aimed at describing the epidemiological characteristics and clinical features of acute bronchiolitis caused by RSV and assessing the related factors to severe acute bronchiolitis in studied patients. Methods A descriptive cross-sectional study was carried out in Haiphong Children's Hospital, Haiphong, Vietnam, for one year, from October 1, 2016, to September 30, 2017. All bronchiolitis admissions < 2 years were included. Results 377 children were evaluated, including 261 boys and 116 girls; children under 6 months accounted for the highest proportion (57%), and 47 (12.5%) of all patients had severe disease. Wheezing was the main reason to be taken to the hospital 261 (69.2%). Clinical symptoms of acute bronchiolitis such as cough, tachypnea, and runny nose were found in all patients. Bronchiolitis cases increased in the winter-spring season, and the highest registered number of patients was 42 in March. Image of bronchiolitis on chest X-ray was found in all patients, and air trapping lung was found in 124 (32.9%) patients. The risk factors included age (≤6 months), low birth weight, preterm birth, nonbreastfeeding for the first six months, early weaning, and exposition to cigarette smoke increased the severe disease (p < 0.05). Conclusion The number of hospitalized infants with bronchiolitis caused by RSV has an upward trend during the winter-spring season (from October to March). This study confirms that age, preterm birth, breastfeeding under 6 months, history of exposure to cigarette smoking, low birth weight, having sibling(s) under five years old going to kindergarten, history of undergoing cesarean section, history of mechanical ventilation, poor living condition, and maternal education are 10 risk factors of severe bronchiolitis caused by RSV.

Determination of predictive risk factors for severe bronchiolitis.

The aim of this study was to determine the predictive risk factors for development of severe bronchiolitis in patients with acute bronchiolitis with no previous chronic disease. Four hundred forty children aged 1-24months hospitalised with acute bronchiolitis, were examined between February 2018 and February 2019 in this prospective study. Eighty-five cases were regarded as severe bronchiolitis and 355 as mild-moderate bronchiolitis. Statistically significant differences were observed between the severe and mild-moderate bronchiolitis groups in terms of weight-for-age z-scores, history of bronchiolitis, haemoglobin levels, and time elapsed between the onset of symptoms and admission. Weight-for-age z-scores, the mean time interval between the onset of symptoms and admission, and mean haemoglobin values were lower in the severe bronchiolitis group while the mean number of bronchiolitis attacks was higher than in the mild-moderate bronchiolitis group. Logistic regression analysis determined that a low weight-for-age z-score increased the risk of severe bronchiolitis development 0.56-fold (CI: 0.409-0.760), a short duration between the onset of symptoms and admission increased the risk 0.62-fold (CI: 0.519-0.735), a frequent history of bronchiolitis increased the risk 1.81-fold (CI: 1.135-2.968) and low haemoglobin levels increased the risk 0.72-fold (CI: 0.537-0.969). Low weight-for-age z-scores, a short duration between the onset of symptoms and admission, a high number of previous attacks and low haemoglobin levels were identified as independent parameters of severe bronchiolitis development.

Risk factors for severe bronchiolitis in Colombia.

High medical costs of treatment of severe bronchiolitis in infants impose a severe economic burden, especially in tropical middle-income countries. There is a critical need therefore to explore the risk factors concerned. In our retrospective cohort study, we included all infants younger than two years admitted in Rionegro, Colombia, owing to bronchiolitis. We used log-binomial regression and estimate prevalence ratios. Out of a total of 417 included, 300 (72.12%) had severe bronchiolitis, with respiratory syncytial virus and current exposure to cigarette smoking being independent predictors.

Risk factors for severe bronchiolitis in children less than 2 years old: a retrospective cohort study

Background: Bronchiolitis is the most common reason for hospitalization and frequent cause of viral infection. This study aimed to determine the risk factors for severe bronchiolitis in children admitted through the emergency department at Sultan Qaboos University Hospital in Oman. Methods: A retrospective chart review was conducted among children

Risk factors for severe bronchiolitis among children in the emergency department at Sultan Qaboos University Hospital

Background and Aim: Bronchiolitis is an acute viral lower respiratory tract infection. It is a common disease among children below 2 years old, resulting in frequent presentation to the emergency department and occasionally admission1 . For proper management of such patients, studying the disease spectrum and the risk factors is important2 . The aim of this study was to investigate the demographics and risk factors for severe bronchiolitis in children (0–2 years old), in the emergency department (ED) at Sultan Qaboos University Hospital (SQUH). Methods: We conducted a retrospective cohort study, including children ( < 2 years old), who came to the ED with a presentation suggestive of bronchiolitis. We reviewed the charts for a two-year period (January 2015–December 2016). Demographic and baseline characteristics were gathered from electronic medical records and then analyzed. We categorized patients into severe and non-severe bronchiolitis according to the guidelines set by the New South Wales (NSW) Ministry of Health in Australia in 2012 for the “Acute Management of Bronchiolitis in Infants and Children”3 . Therefore, in our study children who were considered to have severe bronchiolitis had one of the following: unwell appearance, apneas, severe tachypnea (>70 breaths/min), bradypnea ( < 30 breaths/min), moderate to severe grunting, cyanosis, pallor, oxygen saturation < 90% in air (or < 92% in O2), tachycardia (>180 beats/min) and difficulty in feeding (taking less than 50% of normal feed).We investigated the following risk factors to predict severe bronchiolitis: maternal age, birth weight, prematurity ( < 37 weeks of gestational age), age < 12 weeks, congenital heart defects, congenital respiratory diseases, immunodeficiency, and global developmental delay. We described the cohort using descriptive statistics and performed a logistic regression analysis to determine the risk factors for severe bronchiolitis. Results: Of the 235 children with bronchiolitis, 133 had severe bronchiolitis while 102 had the non-severe form of the disease, with a greater percentage of males than females in both groups. The majority of children with severe bronchiolitis were in the age < 3 months group (32%), while the least was in the ≥ 12 months age group (10%). There was a trend toward statistically significant results for the following factors: chronological age < 12 weeks (OR = 2.67, 95% CI = 0.89–2.67), congenital cardiac diseases (OR = 2.12, 95% CI = 0.85–5.30) and congenital respiratory diseases (OR = 1.86, 95% CI = 0.80–4.27).The following factors were associated with severe bronchiolitis using stepwise logistic regression: increased heart rate (OR = 1.046, 95% CI = 1.026 – 1.066), decreased SpO2 (OR = 0.890, 95% CI = 0.827 - 0.957), male gender (OR = 2.248, 95% CI = 1.105 – 4.573), irritability (OR = 2.209, 95% CI = 1.024 – 4.769) and global developmental delay (OR = 3.5, 95% CI = 1.0 – 12.537). Conclusion: Multiple factors were associated with severe bronchiolitis and three were trending toward significant association including the younger age group, presence of congenital heart and respiratory diseases4. Low saturation, tachycardia and irritability were both part of the diagnostic criteria for severity and risk factors which confirms the clinical importance of these factors. Further investigations with a prospective study and a bigger sample size are required to confirm our findings and find other associated factors.

New therapies for acute RSV infections: where are we?

Respiratory syncytial virus (RSV) infection is one of the main causes of infant hospitalization and mortality. The single-stranded RNA virus codes for 11 proteins of which the F protein, a surface epitope responsible for RSV fusion, is the most targeted for developing antiviral medicines and vaccines. The peak of symptoms occurs around day 4 to 6 of illness and the airway obstruction is merely caused by the host immune inflammatory response. Risk factors for severe bronchiolitis are prematurity, comorbidity, and/or being immunocompromised. At present, there are no curative therapies available for RSV infections and treatment is supportive only. Development of new antiviral medicines is however promising. The aim of this review is to give a summary of the most important new antiviral therapies in clinical development for RSV infection and to explain their mode of action. We therefore performed a literature search on this topic.Conclusion: There are currently at least eight antivirals being investigated in clinical trials. They all use different approaches to either focus on preventing viral fusion with host cells or inhibiting virus replication. Some target RSV surface epitopes like the F protein to halt fusion, others aim for RNA chain termination, while small interfering RNAs downregulate viral protein production. What is known: • RSV bronchiolitis is a very important pediatric disease as it is one of the main causes of infant hospitalization and mortality. By the age of 2years, 95% of all the infants worldwide will have been infected. • The only recommended therapy is supportive since there are no existing curative therapies yet. What this study adds: • This review gives an overview of the current progress in the research field of RSV antivirals with background information on their mode of action.

Prenatal and postnatal tobacco smoke exposure and risk of severe bronchiolitis during infancy.

Maternal prenatal smoking has adverse effects on the growing fetus including those of respiratory nature. Although postnatal smoke exposure is a risk factor for respiratory infections, the effects of prenatal smoking independent of postnatal smoke exposure are less established. We hypothesized that both maternal prenatal smoking, and postnatal smoke exposure are risk factors for severe bronchiolitis during infancy. We performed a case-control study of 1353 children born between 1996 and 2011 at a single teaching hospital. Cases were admitted to the same hospital for bronchiolitis during infancy. Maternal prenatal smoking was collected from birth records. Postnatal smoke exposure was collected from review of electronic health records. Multivariable logistic regression was used to evaluate the independent associations of the two smoking variables with severe bronchiolitis. 6% of cases were exposed to maternal prenatal smoking, compared with 4% of controls (P = 0.10). Postnatal smoke exposure was present in the households of 17% of cases compared with 3% of controls (P < 0.001). In a multivariable model with both smoking variables and adjustment for 10 covariates, maternal prenatal smoking was not a significant risk factor for severe bronchiolitis (adjusted OR = 1.02, 95%CI 0.56-1.84). By contrast, postnatal smoke exposure was associated with >300% increased odds (adjusted OR 4.19, 95%CI 2.51-6.98). Although maternal prenatal smoking has many known adverse effects, it was not associated with increased odds of severe bronchiolitis in either unadjusted or multivariable analyses. Postnatal smoke exposure was a consistently strong risk factor. Our findings support ongoing efforts to decrease infant exposure to ambient smoke.

Interleukin-13 associates with life-threatening rhinovirus infections in infants and young children.

Delineate risk factors associated with severe hypoxemia (O2 sat ≤87%) in infants and children younger than 2 years hospitalized with single pathogen HRV infection. Prospective study in a yearly catchment population of 56 560 children <2 years old between 2011 and 2013 in Argentina. All children with respiratory signs and O2 sat <93% on admission were included. HRV infections were identified by reverse transcriptase-polymerase chain reaction. Epidemiologic, clinical, viral, and immunological risk factors were assessed. Among 5012 hospitalized patients, HRV was detected as a single pathogen in 347 (6.92%) subjects. Thirty-two (9.2%) had life-threatening disease. Traditional risk factors for severe bronchiolitis did not affect severity of illness. HRV viral load, HRV groups, and type II and III interferons did not associate with severe hypoxemia. Interleukin-13 Levels in respiratory secretions at the time of admission (OR = 7.43 (3-18.4); P < 0.001 for IL-13 >10 pg/mL) predisposed to life-threatening disease. Targeted interventions against IL-13 should be evaluated to decrease severity of HRV illness in infancy and early childhood.

Risk factors for severe bronchiolitis caused by respiratory virus infections among Mexican children in an emergency department.

Severe bronchiolitis is the most common reason for hospitalization among children younger than 2 years. This study analyzed the prevalence of community-acquired respiratory virus infection and the risk factors for hospitalization of Mexican children with severe bronchiolitis treated in an Emergency department.This retrospective study included 134 children 2 years or younger with severe viral bronchiolitis, and 134 healthy age-matched controls. The study period was September 2012 to January 2015. We determined the viral etiology and coinfections with multiple viruses and compared the risk factors detected in children with severe viral bronchiolitis with those in the control group.A total of 153 respiratory viruses in these 134 patients, single or mixed infections, were identified: respiratory syncytial virus (RSV) type A or B was the most frequently detected (23.6% and 17.6%, respectively), followed by rhinovirus (RV; 16.3%) and parainfluenza virus (PIV) type 3 (12.4%). Coinfections of 2 respiratory viruses were found in 14.2% of cases; all cases had either RSV type A or B with another virus, the most common being parainfluenza virus or rhinovirus. Exposure to cigarette smoking was independently associated with hospitalization for severe bronchiolitis (OR, 3.5; 95% CI, 1.99–6.18; P = .0001), and having completed the vaccination schedule for their age was a protective factor against adverse outcome (OR, 0.55; 95% CI, 0.35–0.87; P = .010).RSV is a common infection among young children with severe bronchiolitis; thus, developing a vaccine against RSV is essential. Campaigns to reinforce the importance of avoiding childhood exposure to cigarette smoke are also needed.

Pre-birth cohort study of atopic dermatitis and severe bronchiolitis during infancy.

Infants hospitalized for bronchiolitis (i.e. severe bronchiolitis) are at increased risk of childhood asthma. There are many known risk factors for severe bronchiolitis, including cardiac and pulmonary diseases. Less is known about the association between atopic diseases and risk of severe bronchiolitis. We sought to further examine risk factors for severe bronchiolitis, focusing on atopic dermatitis (AD). We conducted a nested cohort study within the Massachusetts General Hospital Obstetric Maternal Study (MOMS), a prospective cohort of pregnant women enrolled during 1998-2006. Children of mothers enrolled in MOMS were included in the analysis if they received care within our health system (n = 5407). Potential risk factors for bronchiolitis and hospitalization data were extracted from the children's electronic health records; we also examined pregnancy and perinatal risk factors collected from the underlying MOMS data. During the first year of life, 125 infants (2.3%) had severe bronchiolitis. Eighteen of these patients had AD; 11 (61%) were diagnosed with AD prior to bronchiolitis hospitalization. In unadjusted analyses, AD was associated with severe bronchiolitis (χ(2) 14.6; p < 0.001). In multivariable analyses adjusting for nine known risk factors for severe bronchiolitis, including demographics, birth season, disposition at birth, cardiac disease, maternal parity, and delivery mode, AD was associated with increased odds of severe bronchiolitis (odds ratio 2.72, 95% confidence interval 1.60-4.63). Atopic dermatitis is significantly associated with severe bronchiolitis in infancy. The mechanism of the AD-bronchiolitis association is unclear and merits further study; this research may shed light on the pathogenesis of asthma.

Pre-Birth Cohort Study of Atopic Dermatitis and Severe Bronchiolitis during Infancy

BACKGROUND Infants hospitalized for bronchiolitis (i.e. severe bronchiolitis) are at increased risk of childhood asthma. There are many known risk factors for severe bronchiolitis, including cardiac and pulmonary diseases. Less is known about the association between atopic diseases and risk of severe bronchiolitis. We sought to further examine risk factors for severe bronchiolitis, focusing on atopic dermatitis (AD). METHODS We conducted a nested cohort study within the Massachusetts General Hospital Obstetric Maternal Study (MOMS), a prospective cohort of pregnant women enrolled during 1998-2006. Children of mothers enrolled in MOMS were included in the analysis if they received care within our health system (n = 5407). Potential risk factors for bronchiolitis and hospitalization data were extracted from the children's electronic health records; we also examined pregnancy and perinatal risk factors collected from the underlying MOMS data. RESULTS During the first year of life, 125 infants (2.3%) had severe bronchiolitis. Eighteen of these patients had AD; 11 (61%) were diagnosed with AD prior to bronchiolitis hospitalization. In unadjusted analyses, AD was associated with severe bronchiolitis (χ(2) 14.6; p < 0.001). In multivariable analyses adjusting for nine known risk factors for severe bronchiolitis, including demographics, birth season, disposition at birth, cardiac disease, maternal parity, and delivery mode, AD was associated with increased odds of severe bronchiolitis (odds ratio 2.72, 95% confidence interval 1.60-4.63). CONCLUSIONS Atopic dermatitis is significantly associated with severe bronchiolitis in infancy. The mechanism of the AD-bronchiolitis association is unclear and merits further study; this research may shed light on the pathogenesis of asthma.

Effect of Previously Administered Medication on Length of Hospital Stay in Patients with Moderate Acute Bronchiolitis

Background: Bronchiolitis is a leading cause of hospitalization in infants and the most common lower respiratory infection of infancy, yet optimal treatment is still debated. Most inpatients with bronchiolitis have been referred to hospitals by their primary care providers, and are usually prescribed inhaled bronchodilators and/or oral corticosteroids despite current recommendations. Aim: To assess the efficacy of inhaled salbutamol and oral corticosteroids received prior to admission in patients with acute bronchiolitis. Methods: Prospective study in the context of a randomized, controlled, double-blind clinical trial. In total, 185 patients with moderate bronchiolitis were included and categorized into 4 groups: patients who received 1) no medication, 2) inhaled salbutamol, 3) oral corticosteroids or 4) a combination of these therapies, prior to admission for more than 24 hours. Patients who received corticosteroids during hospitalization and patients with risk factors for severe bronchiolitis were excluded. Length of stay (LOS) was recorded as the main variable. Secondary variables were clinical status, respiratory rate, and oxygen saturation on admission. Results: Demographic and clinical data were similar in all 4 groups except age, which was lower in the groups that received no medication (p<0.0001). The group that received combined therapy with salbutamol and corticosteroids before admission had a shorter mean LOS compared to the group that did not receive any medication at all (3.76 ± 1.6 vs. 4.66 ± 2.1; p=0.007). There were, however, no differences in any secondary outcomes: clinical severity score, respiratory rate or oxygen saturation. Conclusion: Hospital stay is shorter in outpatients with moderate acute bronchiolitis receiving oral corticosteroids and inhaled salbutamol for more than 1 day before admission than in untreated patients. More studies are needed to confirm these results and to help identify which groups benefit from this treatment.

PO-0183 Role Of Oral Corticosteroids Before Admission In Infants With Acute Moderately Ill Bronchiolitis

<h3>Background and aims</h3> Current evidence does not support a clinically relevant effect of systemic glucocorticoids in reducing length of hospitalisation (LOS) in acute bronchiolitis. To evaluate whether treatment with oral corticosteroids prior to admission (CO) decreases LOS in patients admitted for acute moderate bronchiolitis (MB). <h3>Material and methods</h3> In a context of a randomised, controlled, double-blind clinical trial, 185 patients with MB were included and grouped in receiving CO before admission for more than 24 h or not. Patients who received corticosteroids during hospitalisation and patients with risk factors for severe bronchiolitis were excluded. LOS as the main variable was recorded. Secondary: clinical scale, respiratory rate and oxygen saturation on admission. <h3>Results</h3> 26.5% received corticosteroids before to admission. Demographic and clinical data were similar (p &gt; 0.05): Males (47% vs 51%), exclusively breastfeeding (51% vs 56%), or RSV positive (61% vs 60%), parental smoking (45% vs 39%) and atopy (38% vs 28%). There were statistically significant differences in mean age (3.5 vs 1.7 months, p = 0.000), severity clinical scale (5,37 vs 4.93 points, p = 0.021) and in receiving salbutamol (85.7% vs 19.1%, p = 0.000). There was no difference in respiratory rate (p = 0.584) or oxygen saturation on admission (p = 0.07). The LOS was 2.43 vs 3.22 days, p = 0.004. <h3>Conclusions</h3> In our series, CO administration before admission to BA decreases LOS significantly. The CO group was older but more severe; both can be a confusion factor.

Association of Respiratory Viral Infection and Atopy with Severity of Acute Bronchiolitis in Infants

Purpose: We investigated the influence of respiratory virus and atopic characteristics on the severity of bronchiolitis. Methods: Four hundred and eighteen infants <2-years-old and hospitalized at Daegu Fatima Hospital with bronchiolitis from March 2007 to February 2010 were evaluated. They were detected for specific respiratory viruses in nasopharyngeal aspirates by multiplex reverse transcription-polymerase chain reaction. Clinical severity score, based on respiratory rate, wheezing, chest retraction, and oxygen saturation was assessed at admission. According to the scores, all patients were divided into a mild to moderate bronchiolitis group and a severe group. Clinical data related to host factors, including atopic characteristics and respiratory viruses, were compared among individual groups. Multivariate logistic regression analyses were performed to identify independent risk factors for severe bronchiolitis. Results: A single virus was identified in 365 infants (87%) and multiple viruses in 53 (13%). Respiratory syncytial virus (RSV) was the most common virus detected (51%). RSV and rhinovirus were the viruses most frequently identified in mixed infections in infants hospitalized with bronchiolitis. Infants with coinfections were 3.28 times (95% confidence interval, 1.36 to 7.89) more risk for severe bronchiolitis than those with a single infection. Host factors associated with more severe bronchiolitis included male gender, younger age, prematurity, and chronic cardiorespiratory illness. Type of viruses, personal and family history of atopy, and passive smoking were not significantly associated with bronchiolitis severity. Conclusion: Viral coinfections and host factors, including male gender, younger age, prematurity, and chronic cardiorespiratory illness are relevant risk factors for infants with severe bronchiolitis. (Pediatr Allergy Respir Dis(Korea) 2011;21:302-312)

Risk Factors in Children Hospitalized With RSV Bronchiolitis Versus Non–RSV Bronchiolitis

The trends in hospitalization rates and risk factors for severe bronchiolitis have not been recently described, especially after the routine implementation of prophylaxis for respiratory syncytial virus (RSV) infections. To define the burden of hospitalizations related to RSV and non-RSV bronchiolitis in a tertiary-care children's hospital from 2002 to 2007 and to identify the risk factors associated with severe disease. Medical records of patients hospitalized for bronchiolitis were reviewed for demographic, clinical, microbiologic, and radiologic characteristics as well as the presence of underlying medical conditions. Differences were evaluated between children with RSV and non-RSV bronchiolitis, and multivariable logistic regression analyses were performed to identify independent risk factors for severe disease. Bronchiolitis hospitalizations in children younger than 2 years old (n = 4800) significantly increased from 536 (3.3%) in 2002 to 1241 (5.5%) in 2007, mainly because of RSV infections. Patients with RSV bronchiolitis (n = 2840 [66%]) were younger at hospitalization and had a lower percentage of underlying medical conditions than children hospitalized with non-RSV bronchiolitis (27 vs 37.5%; P < .001). However, disease severity defined by length of hospitalization and requirement of supplemental oxygen, intensive care, and mechanical ventilation was significantly worse in children with RSV bronchiolitis. RSV infection and prematurity, regardless of the etiology, were identified as independent risk factors for severe bronchiolitis. There was a significant increase in hospitalizations for RSV bronchiolitis from 2002 to 2007. A majority of the children with RSV bronchiolitis were previously healthy, but their disease severity was worse compared with those hospitalized with non-RSV bronchiolitis.