Severity of illness models for respiratory syncytial virus-associated hospitalization

Six-monthly palivizumab prophylaxis effectively reduced RSV-associated hospitalization rates of preterm infants in a subtropical area: a population-based cohort study

BACKGROUND

To evaluate the effects of 6-monthly palivizumab on respiratory syncytial virus-associated hospitalization (RSVH) in preterm infants in an area without RSV seasonality.

METHODS

RSV prophylaxis with 6-monthly palivizumab in infants born at gestational age (GA) ≤28 weeks or those born at GA 29-35 weeks with bronchopulmonary dysplasia (BPD) was implemented in Taiwan since 2010. RSVH, use of mechanical ventilation (MV), admission to intensive care unit (ICU), length of hospital stay, and annual mortality were compared between the historical control group (no prophylaxis, 2008-2009) and the prophylaxis group (2011-2013).

RESULTS

The annual RSVH rates decreased in the target population and in subgroups of infants who received prophylaxis (all target infants: odds ratio [OR], 0.43; 95% confidence interval [CI], 0.29-0.65). No difference was observed in MV and ICU usage and 1-year mortality in the ≤28 weeks subgroup. In the GA 29-35 weeks with BPD subgroup, ICU usage and 1-year mortality rates were significantly reduced with palivizumab prophylaxis regimen. A significant decrease was noted in the annual mortality and ICU admission rates of infants who received prophylactic treatment.

CONCLUSION

Six-monthly palivizumab treatment reduced the RSVH rate, ICU usage, and annual mortality rates of target infants in an area without RSV seasonality.

Predictors of prolonged length of hospital stay for infants with bronchiolitis

Among inpatients suffering from bronchiolitis, approximately a quarter may undergo a prolonged length of stay (LOS) for the treatment of their respiratory condition. However, there have been few research studies that have evaluated variables that may be associated with a prolonged LOS in these patients, especially in low-income and middle-income countries, where the clinical and economic burden of the disease is the greatest. In an analytical single-center cross-sectional study, we included a population of patients with acute bronchiolitis hospitalized between March and June 2016. We collected demographic and clinical information and the LOS of each patient. Prolonged LOS for bronchiolitis was defined as at least one hospital stay of 5 or more days. A total of 303 patients were included, with 176 (58.1%) male and a median (IQR) age of 3.0 (1.0-7.0) months. After controlling for gender, history of bronchopulmonary dysplasia, number of days with respiratory symptoms, the presence of apnea as an initial manifestation of bronchiolitis, and other underlying disease conditions, we found that the independent predictors of prolonged LOS for bronchiolitis in our study population included age (OR 0.92; 95% CI 0.84 to 0.99; p=0.049), history of prematurity (OR 6.34; 95% CI 1.10 to 36.46; p=0.038), respiratory syncytial virus isolation (OR 1.92; 95% CI 1.02 to 3.73; p=0.048), and initial oxygen saturation (OR 0.94; 95% CI 0.88 to 0.98; p=0.048). The factors identified should be taken into account when planning policies to reduce the duration of hospital stay in infants with bronchiolitis.

Prospective observational study in two Dutch hospitals to assess the performance of inflammatory plasma markers to determine disease severity of viral respiratory tract infections in children

INTRODUCTION

Respiratory viruses causing lower respiratory tract infections (LRTIs) are a major cause of hospital admissions in children. Since the course of these infections is unpredictable with potential fast deterioration into respiratory failure, infants are easily admitted to the hospital for observation. The aim of this study was to examine whether systemic inflammatory markers can be used to predict severity of disease in children with respiratory viral infections.

METHODS

Blood and nasopharyngeal washings from children <3 years of age with viral LRTI attending a hospital were collected within 24 hours (acute) and after 4-6 weeks (recovery). Patients were assigned to a mild (observation only), moderate (supplemental oxygen and/or nasogastric feeding) or severe (mechanical ventilation) group. Linear regression analysis was used to design a prediction rule using plasma levels of C reactive protein (CRP), serum amyloid A (SAA), pentraxin 3 (PTX3), serum amyloid P component and properdin. This rule was tested in a validation cohort.

RESULTS

One hundred and four children (52% male) were included. A combination of CRP, SAA, PTX3 and properdin was a better indicator of severe disease compared with any of the individual makers and age (69% sensitivity (95% CI 50 to 83), 90% specificity (95% CI 80 to 96)). Validation in 141 patients resulted in 71% sensitivity (95% CI 53 to 85), 87% specificity (95% CI 79 to 92), negative predictive value of 64% (95% CI 47 to 78) and positive predictive value of 90% (95% CI 82 to 95). The prediction rule was not able to identify patients with a mild course of disease.

CONCLUSION

A combination of CRP, SAA, PTX3 and properdin was able to identify children with a severe course of viral LRTI disease, even in children under 2 months of age. To assess the true impact on clinical management, these results should be validated in a prospective randomised control study.

Nasopharyngeal gene expression, a novel approach to study the course of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) causes mild infections in the vast majority of children. However, in some cases, it causes severe disease, such as bronchiolitis and pneumonia. Development of severe RSV infection is determined by the host response. Therefore, the main aim of this study was to identify biomarkers associated with severe RSV infection. To identify biomarkers, nasopharyngeal gene expression was profiled by microarray studies, resulting in the selection of five genes: ubiquitin D, tetraspanin 8, mucin 13, β-microseminoprotein and chemokine ligand 7. These genes were validated by real-time quantitative PCR in an independent validation cohort, which confirmed significant differences in gene expression between mildly and severely infected and between recovery and acute patients. Nasopharyngeal aspirate samples are regularly taken when a viral respiratory tract infection is suspected. In this article, we describe a method to discriminate between mild and severe RSV infection based on differential host gene expression. The combination of pathogen detection and host gene expression analysis in nasopharyngeal aspirates will significantly improve the diagnosis and prognosis of respiratory tract infections.

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.

Validity of respiratory scores in bronchiolitis

OBJECTIVE

The primary objective of this study was to establish the validity and reliability of 2 respiratory scores, the Respiratory Distress Assessment Instrument (RDAI) and the Children's Hospital of Wisconsin Respiratory Score (CHWRS), in bronchiolitis. A secondary objective was to identify the respiratory score components that most determine overall respiratory status.

METHODS

This was a prospective cohort study in infants aged < 1 year seen at Children's Hospital of Wisconsin for bronchiolitis. We evaluated: (1) discriminative validity (the score's ability to discriminate between 2 different outcomes) of the respiratory scores to identify emergency department (ED) disposition by using receiver operating characteristic curves; and (2) construct validity (the score's ability to measure what it is thought to measure, overall respiratory status) by using length of stay (LOS) as a proxy for disease severity and comparing correlations between changes in respiratory scores and LOS. Interrater reliability was established by using intraclass correlation. The contribution of individual respiratory score components to determine ED disposition was studied by using multivariate logistic regression.

RESULTS

A total of 195 infants were included. The area under the receiver operating characteristic curve was 0.68 for CHWRS versus 0.51 for RDAI in predicting disposition. There was no correlation between initial respiratory scores or change in respiratory scores over the first 24 hours and LOS. Item analysis revealed that oxygen delivery, subcostal retractions, and respiratory rate were independently correlated with ED disposition. The CHWRS was more reliable than the RDAI.

CONCLUSIONS

The CHWRS had modest discriminative validity in predicting ED disposition. Neither the CHWRS nor the RDAI had good construct validity. Respiratory rate, oxygen need, and presence of retractions were most useful in predicting ED disposition.

Morbidity and outcome of severe respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV) is the main cause of severe acute respiratory infection (SARI) in infants and young children. This study aimed to identify risk factors for intensive care unit (ICU) admission, prolonged length of stay (PLOS), and mortality in patients hospitalized with SARI caused by RSV.

METHODS

This prospective cohort study included children hospitalized with SARI (according to the World Health Organization definition) and whose laboratory results proved RSV infection during the period from February 2010 to May 2011.

RESULTS

Out of 240 enrolled patients, 24 patients (10%) were admitted to the ICU, 57 patients (24.3%) had a PLOS of >9 days and 12 patients (5%) died. The presence of cyanosis (P = 0.000; OR, 351.7) and lung consolidation (P = 0.006, OR, 9.3) were independent risk factors associated with ICU admission. The need for ICU admission (P = 0.000; OR, 6.1) and lung consolidation (P = 0.008, OR, 2.46) were independent risk factors associated with PLOS. The presence of an underlying congenital heart disease (P = 0.03, OR, 18.3), thrombocytopenia (P = 0.04, OR, 32.86) and mechanical ventilation (P = 0.000; OR, 449.4) were the only independent risk factors associated with mortality in our study.

CONCLUSIONS

Early recognition of risk factors for complicated RSV disease on admission prompts early interventions and early ICU admissions for these children.

Bronchiolitis: Can objective criteria predict eligibility for brief hospitalization?

OBJECTIVE

To determine if 3 objective criteria - pulse oximetry, respiratory syncytial virus (RSV) testing, and age - could be used to predict which children hospitalized with bronchiolitis will have brief (<36 hour) hospitalizations and therefore be potential candidates for admission to short-stay observation units.

METHODS

This was a retrospective medical record review of medically uncomplicated children 3 to 24 months of age with emergency department and hospital discharge diagnoses consistent with bronchiolitis who were admitted to a general pediatric ward in our university-based, tertiary care hospital between Jan. 1, 1992, and Nov. 12, 2002. Multiple logistic regression was used to assess the predictor variables.

RESULTS

Our study consisted of 225 patients (45% female) with a median age of 7 months (interquartile range [IQR], 4-11 mo; range, 3-22 mo). Median pulse oximetry value was 94% (IQR 91%-96%; range 76%-100%), and 71% of the patients tested positive for RSV. Thirty children (13%) had brief hospitalizations <36 hours, and the median hospital length of stay for the entire study group was 70 hours (IQR 46-108 h; range 6-428 h). None of the 3 predictor variables were independently associated with brief hospitalization.

CONCLUSIONS

Pulse oximetry, RSV testing and age do not predict which children will have brief hospitalizations and are appropriate candidates for admission to short-stay observation units.

Factors predicting prolonged hospital stay for infants with bronchiolitis

BACKGROUND

Prior prediction models for length of stay (LOS) in bronchiolitis have focused more on birth- and disease-related risk factors than on early hospital course factors, particularly common clinical markers including respiratory status and caloric intake.

OBJECTIVES

1) Study the associations of various clinical markers and LOS; and 2) develop a LOS prediction model.

DESIGN

Retrospective cohort study.

SETTING

Children's Hospital of Wisconsin.

PATIENTS

Inclusion criteria were: age < 365 days old; admission between November 1, 2004 and April 15, 2005; final diagnosis of bronchiolitis; placement on the bronchiolitis treatment protocol; and lack of concurrent condition impacting LOS.

RESULTS

During the study period, 272/347 infants admitted with bronchiolitis met inclusion criteria. On hospital day 2, infants in the prolonged LOS group (≥ 108 hours) had a significantly greater number of hours on supplemental oxygen, maximum supplemental oxygen use, minimum supplemental oxygen use, maximum respiratory rate, mean respiratory score, and number of times suctioned. They had significantly lower minimum oxygen saturation and caloric intake. Recursive partitioning demonstrated five variables (hours of supplemental oxygen, maximum respiratory rate, minimum supplemental oxygen use, gestation, and caloric intake) to predict short or prolonged LOS with an area under the receiver-operator characteristic curve of 0.89/0.72 in the learning/test trees; sensitivity, 0.85; and specificity, 0.82.

CONCLUSIONS

There are important differences between infants with bronchiolitis having short and prolonged hospital stays, including several clinical markers identifiable on hospital day 2. This model may be a useful prediction tool for targeting early interventions for high-risk infants.

[Consensus conference on acute bronchiolitis (VI): prognosis of acute bronchiolitis. Review of scientific evidence]

We present a review of the evidence on prognosis of acute bronchiolitis, risk factors for severe forms, symptom or severity scores and risk of post-bronchiolitis asthma. Documented risk factors of long stay or PICU admission in hospitalized patients are: bronchopulmonary dysplasia and/or chronic lung disease, prematurity, congenital heart disease and age less than 3 months. Other less well documented risk factors are: tobacco exposure, history of neonatal mechanical ventilation, breastfeeding for less than 4 months, viral co-infection and other chronic diseases. There are several markers of severity: toxic appearance, tachypnea, hypoxia, atelectasis or infiltrate on chest radiograph, increased breathing effort, signs of dehydration, tachycardia and fever. Although we have some predictive models of severity, none has shown sufficient predictive validity to recommend its use in clinical practice. While there are different symptom or severity scores, none has proven to be valid or accurate enough to recommend their preferable application in clinical practice. There seems to be a consistent and strong association between admission due to bronchiolitis and recurrent episodes of wheezing in the first five years of life. However it is unclear whether this association continues in subsequent years, as there are discordant data on the association between bronchiolitis and asthma.

Predictors of respiratory failure among previously healthy children with respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV)-related disease is the leading cause of hospitalization among infants, with approximately 7% to 21% of these patients developing acute respiratory failure.

OBJECTIVE

The aim of this study was to identify clinical variables at initial presentation in the emergency department (ED) that may predict the subsequent need for mechanical ventilation among previously healthy, RSV-infected children who require pediatric intensive care unit (PICU) hospitalization.

STUDY DESIGN

This is a retrospective study of 67 previously healthy, RSV-infected patients admitted from January 1997 to March 2000 to the PICU. The primary outcome for this study was the need for mechanical ventilation. The relationship between clinical variables at initial ED presentation and the need for mechanical ventilation were explored using univariate and multiple logistic regression analysis.

RESULTS

On multivariate analysis, the presence of lethargy (odds ratio [OR], 12.2; P = .005), grunting (OR, 9.3; P = .01), and a Paco(2) 65 mm Hg or greater (OR, 11.8; P = .013) were clinical factors at initial presentation in the ED associated with the subsequent need for mechanical ventilation among the study cohort. A developmental model that included lethargy, grunting, and a Paco(2) of 65 mm Hg or greater performed well as a prediction model. The developmental model had a sensitivity of 71%, specificity of 96%, a positive predictive value of 86%, and a negative predictive value of 91%.

CONCLUSIONS

The presence of lethargy, grunting, and a Paco(2) of 65 mm Hg or greater at initial presentation in the ED were predictive for the subsequent need for mechanical ventilation in previously healthy, RSV-infected children admitted to the PICU.

Nasal continuous positive airway pressure with heliox versus air oxygen in infants with acute bronchiolitis: a crossover study

OBJECTIVE

The purpose of this work was to evaluate the effects of administering either heliox or air oxygen in combination with nasal continuous positive airway pressure in infants with refractory bronchiolitis.

PATIENT AND METHODS

We conducted a prospective, interventional, single-center, crossover study in a teaching hospital including infants 1 month to 2 years of age, consecutively admitted to the PICU from February 2004 to February 2005 for treatment of severe acute bronchiolitis unresponsive to therapy. Patients with a clinical score (Modified Wood's Clinical Asthma Score) of >5, arterial oxygen saturation of <92%, or transcutaneous CO(2) pressure of >50 mmHg despite supportive therapy, nebulized L-epinephrine, and heliox therapy through a nonrebreathing reservoir face mask were eligible. During the study period, 40 infants with bronchiolitis were admitted to the PICU; 12 fulfilled inclusion criteria. A predetermined balanced sequential allocation to either 30 minutes of treatment with nasal continuous positive airway pressure with heliox or to air-oxygen nasal continuous positive airway pressure was performed. Measurements were taken at baseline and after 30 minutes of each treatment.

RESULTS

Baseline mean values were as follows: nasal continuous positive airway pressure of 7.2 cmH(2)O; clinical score of 7.7 points; transcutaneous CO(2) pressure of 61.6 mmHg; and arterial oxygen saturation of 88.6%, with the fraction of inspired oxygen at 35.4%. Clinical score, transcutaneous CO(2) pressure, and arterial oxygen saturation improved during the study time with both heliox-nasal continuous positive airway pressure and air-oxygen-nasal continuous positive airway pressure: after 1 hour, the clinical score fell 1.7 points, transcutaneous CO(2) pressure decreased 8.2 mmHg, and arterial oxygen saturation increased by 7.7%. Improvement in clinical score was double with heliox-nasal continuous positive airway pressure compared with the air-oxygen-nasal continuous positive airway pressure (2.12 vs 1.08 points), and the fall in the transcutaneous CO(2) pressure was greater with heliox-nasal continuous positive airway pressure compared with air-oxygen-nasal continuous positive airway pressure (9.7 vs 5.4 mm Hg). There was no difference in arterial oxygen saturation between groups. No patients required endotracheal intubation. No adverse effects attributable to either of the study interventions were detected.

CONCLUSIONS

Nasal continuous positive airway pressure improves the clinical score and the CO(2) elimination of infants with refractory bronchiolitis. These positive effects are significantly enhanced when nasal continuous positive airway pressure is combined with heliox instead of air oxygen. Both techniques are noninvasive, seem safe, and may reduce the need for endotracheal intubation.

Neutrophil but not eosinophil inflammation is related to the severity of a first acute epidemic bronchiolitis in young infants

Acute bronchiolitis is the main cause of emergency visits and hospitalizations in infants. Recent data suggest that neutrophil- and eosinophil-mediated inflammations were part of bronchiolitis pathophysiology. Apart from the defined risk factors, few was known on the underlying pathophysiology, which might point out the differences observed in the severity of the disease. The aim of this study was to assess whether the clinical severity of acute epidemic bronchiolitis in young infants might be related to a specific underlying inflammatory process. Total and differential cell counts, IL-8, eotaxin, eosinophil cationic protein (ECP) and albumin levels were assessed at the time of admission in bronchial secretions from 37 infants (median age 17 wk) with acute bronchiolitis. Outcome severity variables were: hypoxemia, Silverman score, tachypnea, feeding alteration, and duration of hospitalization. Neutrophils predominated, and eosinophils were present in 54% of the infants. IL-8 levels strongly correlated with ECP and albumin levels. Albumin levels were correlated with ECP and eotaxin levels. IL-8 levels were higher in infants with hypoxemia and inversely related with SaO(2) levels. IL-8 and albumin levels significantly rose with respiratory rate, and Silverman score. IL-8, albumin and ECP levels were significantly higher in infants hospitalized >/=7 days. Furthermore, IL-8 levels were correlated with the duration of hospitalization. Neither cell counts nor eotaxin levels were related to the severity criteria studied. This study suggests that IL-8-associated airway inflammation significantly contributed to the severity of acute epidemic bronchiolitis.

Nasal continuous positive airway pressure with heliox in infants with acute bronchiolitis

This is the first study aiming to assess the effects of heliox in combination with nasal continuous positive airway pressure (Hx-nCPAP) as a rescue treatment in infants with refractory acute bronchiolitis. Fifteen out of 78 infants with acute bronchiolitis consecutively admitted to PICU fulfilled the inclusion criteria: clinical score>or=5 or arterial oxygen saturation (SatO2)<or=92% or PCO2>50 mmHg, despite supportive therapy, nebulized L-epinephrine, and heliox therapy through non-rebreathing reservoir facemask. Hx-nCPAP was added as a rescue treatment. Baseline mean (standard deviation) values were: clinical score of 7.4 (1.2) points; PCO2 of 63.8 (12) mmHg; respiratory rate (RR) of 66.4 (9.9); and SatO2 of 88.6 (4.7)%. Clinical score, PCO2, RR and SatO2 improved during the study time (P<0.05). After 1 h the mean clinical score decreased by 1.5 points, with a total average decrease of 3.5 points at the end of the study period. The mean PCO2 diminished by 9 and 25 mmHg, after 1 and 48 h, respectively. The mean RR decreased 13 rpm after 1 h and 30 rpm after 48 h. The Hx-nCPAP total duration ranged from 2 to 14 days. Only one patient required endotracheal intubation. No adverse effects were detected. All patients recovered fully. In conclusion, Hx-nCPAP improved the clinical score, decreased the tachypnea and enhanced the CO2 elimination of infants with refractory acute bronchiolitis within 1h of administration, in a safe and non-invasive manner. Hx-nCPAP might reduce the need for endotracheal intubation. Further studies are needed.

A validated clinical model to predict the need for admission and length of stay in children with acute bronchiolitis

OBJECTIVE

To develop and validate a logistic regression model to predict need for admission and length of hospital stay in children presenting to the Emergency Department with bronchiolitis.

SETTING

Two children's hospitals in Dublin, Ireland.

METHODS

We reviewed 118 episodes of bronchiolitis in 99 children admitted from the Emergency Department. Those discharged within 24 h by a consultant/attending paediatrician were retrospectively categorized as suitable for discharge. We then validated the model using a cohort of 182 affected infants from another paediatric Emergency Department in a bronchiolitis season 2 years later. In the validation phase actual admission, failed discharge, and age less than 2 months defined the need for admission.

RESULTS

The model predicted admission with 91% sensitivity and 83% specificity in the validation cohort. Age [odds ratio (OR) 0.86, 95% confidence interval (CI) 0.76-0.97], dehydration (OR 2.54, 95% CI 1.34-4.82), increased work of breathing (OR 3.39, 95% CI 1.29-8.92) and initial heart rate above the 97th centile (OR 3.78, 95% CI 1.05-13.57) predicted the need for admission and a longer hospital stay.

CONCLUSION

We derived and validated a severity of illness model for bronchiolitis. This can be used for outcome prediction in decision support tools or severity of illness stratification in research/audit.

Severity of respiratory syncytial virus bronchiolitis is affected by cigarette smoke exposure and atopy

OBJECTIVE

Respiratory syncytial virus (RSV) bronchiolitis is a common cause of hospitalizations in children and has been increasingly identified as a risk factor in the development of asthma. Little is known about what determines the severity of RSV bronchiolitis, which may be helpful in the initial assessment of these children.

DESIGN

We evaluated a variety of environmental and host factors that may contribute to the severity of RSV bronchiolitis in the RSV Bronchiolitis in Early Life prospective cohort study. Severity of bronchiolitis was based on the quantization of lowest O(2) saturation and the length of stay. These factors included the child's and family's demographics, presence of household allergens (dust mite, cat, dog, and cockroach), peripheral blood eosinophil count, immunoglobulin E level, infant feeding, prior illnesses, exposure to intrauterine and postnatal cigarette smoke, and family history of atopy.

PATIENTS

We prospectively enrolled 206 hospitalized infants, all under 12 months old (4.0 +/- 3.3 months old), with their first episode of severe RSV bronchiolitis (mean O(2) saturation: 91.6 +/- 7.3%; length of stay: 2.5 +/- 2.5 days; presence of radiographic opacities: 75%). Patients were excluded for a variety of reasons including previous wheezing, regular use of bronchodilator or antiinflammatory medications, any preexisting lung disease including asthma, chronic lung disease of prematurity/bronchopulmonary dysplasia, or cystic fibrosis; gastroesophageal reflux disease on medical therapy; or congenital anomalies of the chest or lung.

RESULTS

Age was found to be a significant factor in the severity of infection. The younger an infant was, the more severe the infection tended to be as measured by the lowest oxygen (O(2)) saturation. We also found that infants exposed to postnatal cigarette smoke from the mother had a lower O(2) saturation than those not exposed. However, there was no significant difference in RSV bronchiolitis severity between infants exposed only to intrauterine smoke and those infants never exposed to cigarette smoke. Infants with a family history of atopy, especially a maternal history of asthma or hay fever, had a higher O(2) saturation. Although a history of maternal atopy seemed to be protective, there was no association between allergens and bronchiolitis severity, although 25% of households had elevated allergen levels. Black infants demonstrated less severe RSV bronchiolitis than their white counterparts. Multivariate analysis revealed age, race, maternal atopy, and smoking to be associated with severity of RSV bronchiolitis.

CONCLUSION

The severity of RSV bronchiolitis early in life seems modified by postnatal maternal cigarette smoke exposure and atopy and age of the infant, not by levels of allergens in the home environment.

Cardiac troponin i as a predictor of respiratory failure in children hospitalized with respiratory syncytial virus (RSV) infections: a pilot study

This pilot study was performed to assess the use of cardiac troponin I to predict respiratory failure in children admitted to the hospital with respiratory syncytial virus (RSV) infections. We enrolled a prospective convenience sample of children under 5 years of age who were admitted to our university-based, tertiary care children's hospital from December 1, 2000, to February 1, 2002, with RSV infections. A cardiac troponin I was drawn at admission. We assessed the test characteristics for positive cardiac troponin I (defined as >0.3 ng/mL, the manufacturer's upper limit of normal) in correctly identifying children who had respiratory failure as evidenced by the need for endotracheal intubation. Twenty-five children from 9 days to 38 months of age were included. Ten children had a positive cardiac troponin I and 3 of these children had respiratory failure. A positive cardiac troponin I demonstrated a sensitivity of 100%, specificity 68%, positive predictive value of 30%, negative predictive value of 100%, and accuracy of 72%. The area under the receiver operating characteristic curve was 0.939 (95% confidence interval, 0.820-1.0), suggesting a high degree of discriminatory power in selecting children with respiratory failure. A sample size calculation revealed that a follow-up study of 359 patients is needed before the clinical use of cardiac troponin I for this purpose.

Differences in admission rates of children with bronchiolitis by pediatric and general emergency departments

OBJECTIVE

It is uncertain whether pediatric and general emergency departments have different admitting practices regarding children with bronchiolitis. The objective of this study was to quantify the differences in admission practices between pediatric and general emergency departments of children with bronchiolitis in 1 North American metropolitan area, controlling for various factors such as clinical severity, comorbid conditions, and socioeconomic status.

DESIGN

Retrospective cohort review of emergency department visits from April 1992 to March 1997.

SETTING

Five emergency departments (1 pediatric and 4 general) serving the Calgary Health Region, which encompasses approximately 850 000 people.

PATIENTS

All children residing within the region who visited a regional emergency department and were diagnosed to have bronchiolitis (International Classification of Diseases, Ninth Revision code 466.1, primary or secondary diagnosis).

MAIN OUTCOME MEASURE

Population-standardized estimates of admission rates.

RESULTS

The medical charts of 3091 children diagnosed to have bronchiolitis during the study period were reviewed. Of this number, 2496 children were evaluated at the pediatric emergency department, and 629 (25%) were admitted. The remaining 595 (19%) were evaluated at the general emergency departments, and 221 (37%) were admitted. Controlling for age, gender, estimated family income based on postal code, medical comorbidity, and clinical severity estimated by presenting respiratory rate and room air oxygen saturation, population-standardized estimates for admission rates at the pediatric and general emergency departments were 24% (standard error: 1%) and 43% (standard error: 2%), respectively.

CONCLUSION

Children diagnosed to have bronchiolitis at the Calgary Health Region's pediatric emergency department were about half as likely to be admitted to the hospital as children diagnosed at the region's general emergency departments.

Prediction of duration of hospitalization in respiratory syncytial virus infection

Identification of variables that predict duration of RSV-associated hospitalization may be useful in the identification of preventive and therapeutic strategies. A recently published prediction model (Michigan model) for the duration of hospitalization in RSV infection demonstrated good discrimination between children with and without an increased likelihood of a hospital stay >or= 7 days, based on variables such as log weight, congenital heart disease, failure to thrive, premature birth, bronchopulmonary dysplasia, other pulmonary diseases, miscellaneous conditions, early mechanical ventilation, and early ribavirin treatment (receiver operating characteristic (ROC) area, 0.89). Validation of this model is of particular interest for Europe, since the mean duration of hospitalization in The Netherlands is approximately twice that in the USA. The objective of the current study was 1) to validate the Michigan model for RSV hospitalized patients in a large university hospital in The Netherlands, and 2) to develop our own prediction model for a prolonged hospital stay. Data from 177 children younger than 12 months of age admitted with confirmed RSV infection to the Sophia Children's Hospital Rotterdam between 1992-1995, were used for valiation of the Michigan model and derivation of the Rotterdam model. Mean duration of hospitalization for the Rotterdam database was 10.3 (+/-6.3) days, with a median of 9 days; 138 (78%) patients had a hospital stay >or= 7 days. The Michigan model performed poorly when applied to the Rotterdam database, with an ROC area of 0.65 (95% CI, 0.57-0.73). The Rotterdam prediction model (hospital stay >or= 9 days, the median in our database) considered weight and need for oxygen supplementation. The ROC area was 0.65 (95% CI, 0.57-0.73). When using data from patients for the 1995-1996 season, the ROC area was 0.52 (95% CI, 0.34-0.72). The Michigan and the Rotterdam models failed to identify a considerable number of patients who had a prolonged hospital stay, with a low false-positive rate. We conclude that neither the Michigan, nor the Rotterdam model reliably predicted the duration of hospitalization based on demographic and clinical variables.

[Prospective regional study of an epidemic of respiratory syncytial virus (RSV) bronchiolitis]

This prospective study was designed to identify risk factors associated with admission in pediatric intensive care units (PICU) among infants hospitalized for treatment of RSV induced bronchiolitis. This study was population-based and was conducted in Burgundy, a French region with 1,800,000 inhabitants where passive immunoprophylaxis for RSV bronchiolitis was not set up at the time of the study.

RESULTS

From December 1st 1999 to April 30th 2000, 484 infants were hospitalized for RSV bronchiolitis in Burgundy: 19.6% were born prematurely (gestational age [GA] below 37 weeks) and at admission, 68.3% had a postnatal age below six months (mean = 5 +/- 5.9 months; median value = 3 months). The duration of hospitalization was 7.3 +/- 12.4 days (median value = 6 days). Among the 484 infants, 31 (6.4%) needed admission in PICU, eight needed mechanical ventilation (1.7%) and one died (0.2%). Univariate analysis identified anamnestic risk factors associated with admission in PICU: prematurity; low birth weight; past history of neonatal respiratory distress syndrome (RDS); mechanical ventilation for RDS treatment; bronchopulmonary dysplasia (BPD) and congenital heart disease. Multivariate analysis identified three independent factors associated with an increased risk for admission in PICU: GA below 32 weeks; RDS and congenital heart disease.

CONCLUSION

This study suggests that population at risk for severe RSV bronchiolitis with PICU admission should include all very preterm infants with RDS whatever the outcome of RDS (with or without BPD). These epidemiological data could be helpful to set up indications for passive immunoprophylaxis of RSV induced bronchiolitis.