Long-term effects of respiratory syncytial virus (RSV) bronchiolitis in infants and young children: a quantitative review

One of the major questions regarding long-term side effects of bronchiolitis by respiratory syncytial virus (RSV) is whether or not it induces asthma in later life. In this quantitative review, the data of 10 controlled studies are analysed. METHODS: Follow-up studies of RSV bronchiolitis published between January 1978 and December 1998 were identified through a MEDLINE search. Studies were selected if (i) postnatal age at the time of the initial illness was below 12 mo, (ii) all children were hospitalized for RSV bronchiolitis, (iii) the diagnosis RSV was virologically confirmed in all cases, and (iv) a control group was used. RESULTS: Six studies met all selection criteria. Up to 5 y of follow-up after RSV bronchiolitis in infancy, 40% of children reported wheezing as compared to only 11% in the control group (p <0.001). Between 5 and 10 y of follow-up 22% of the bronchiolitis group reported wheezing against 10% of the control group (p = 0.19). The incidence of recurrent wheezing as defined by three or more wheezing episodes also decreased with increasing years of follow-up: at 5 or more years of follow-up the difference between the RSV group and the control group was no longer significant. Furthermore, the presence of either a personal and/or a family history of either atopy and/or asthma did not differ between the two groups. CONCLUSIONS: Wheezing is common after RSV bronchiolitis in infancy. It may persist for > or = 5 y of follow-up. However, no significant difference between the RSV bronchiolitis and the control group was observed regarding recurrent wheezing by 5 y of follow-up. No significant difference between the RSV bronchiolitis and the control group were found regarding a personal history of atopy, a family history of atopy and/or asthma. Therefore it seems unlikely that RSV bronchiolitis is a cause of atopic asthma in later life.     

Urine leukotriene E4 and eosinophil cationic protein in nasopharyngeal aspiration from young wheezy children

Respiratory syncytial virus (RSV) infection is a risk factor for the development of asthma. It is very hard to distinguish bronchiolitis with respiratory virus infection from allergic asthma at first wheezing attack in early childhood. To distinguish wheezing children with RSV bronchiolitis from asthmatic children, we measured leukotriene E(4)(LTE(4)) in urine and ECP in nasopharyngeal aspiration (NPA) at first day of admission with wheezing attack. Thirty-two non-atopic children younger than the age of 3 yr with RSV induced bronchiolitis, 35 atopic asthmatic children with/without respiratory viral infection, and 23 children who exhibited no evidence of atopy, asthma, or virus infections as controls were selected in this study. We measured urinary LTE(4) and ECP level in NPA from subjects. Urinary LTE(4) concentrations in children with asthma were significantly higher than urinary LTE(4) in bronchiolitis and in controls (240.8 +/- 129.8 vs. 162.8 +/- 73.9 vs. 85.1 +/- 31.6 pg/ml). Children with RSV infection demonstrated higher urinary LTE(4) levels compared to children without RSV infection among asthmatic children. ECP in NPA was significantly correlated with urinary LTE(4) (r = 0.57, p < 0.01) in children entered this study who had detectable levels for both LTE(4) and ECP. In summary, Urinary LTE(4) concentrations may be suggested to useful mediators for differential diagnosis of wheezy diseases in early childhood. RSV infection also is associated with synergizing LT biosynthesis and this study demonstrated ECP in NPA was significantly correlated with urinary LTE(4) and may suggest that cysteinyl leukotriene initiate the production of ECP in early childhood, which could contribute to the development of wheeze.     

Lung function and bronchial hyper-responsiveness 11 years after hospitalization for bronchiolitis

AIM: Atopic infants hospitalized for wheezing not caused by respiratory syncytial virus (RSV) carry the highest risk for later asthma. In the present paper, early risk factors for later lung function abnormalities and for bronchial hyper-responsiveness (BHR) were evaluated in 81 children, hospitalized for bronchiolitis in infancy, at the median age of 12.3 years. METHODS: The basic data, including data on atopy in children and viral aetiology of bronchiolitis, had been collected on entry to the study at less than 2 years of age. Lung function was studied by flow-volume spirometry (FVS), and BHR by methacholine and exercise challenge tests 11.4 years after hospitalization during infancy. RESULTS: RSV aetiology of bronchiolitis was associated with reduced forced vital capacity (FVC; 93.65% of predicted +/- 11.05 vs. 99.57%+/- 12.59, p = 0.009). Early sensitization to inhalant allergens (OR 12.59, 95% CI 2.30-68.77) and maternal smoking during pregnancy (OR 4.58, 95% CI 1.28-16.39) were associated with BHR to exercise, and early atopic dermatitis (OR 3.48, 95% CI 1.09-11.10) was associated with BHR to methacholine. CONCLUSIONS: RSV bronchiolitis was associated with a restrictive pattern of lung function. Early atopy and maternal smoking during pregnancy may play a role in the development and persistence of BHR.     

Association between pronounced IgA response in RSV bronchiolitis and development of allergic sensitization

Forty-five children who had heen hospitalized with bronchiolitis caused by respiratory syncytial virus (RSV) at a mean age of 4 months, and 90 matched control children, were tested for occurrence of RSV antibodies at one year of age. Of the children who had suffered from bronchiolitis. forty had demonstrable IgG antibodies, whereas the remaining five only had IgA antibodies against RSV. In the control group. 42% were RSV seropositive. The anti-RSV IgA antibody titres tended to be higher in patients with bronchiolitis ihan in controls and a larger proportion of the seropositive children in the former than in the latter group had demonstrable IgG antibodies. These fmdings suggest that RSV infections causing bronchiolitis are more often associated with a strong antibody response than are mild cases of the infection.
Follow-up of the children at 3 years of age showed that allergic sensitization and development of asthma had occurred much more frequently in children with past RSV bronchiolitis than in controls. Children with past RSV bronchiolitis who later developed allergic sensitization had elevated RSV IgA antibody titres at one year of age more frequently than children with past RSV-bronchiolitis. who were not sensitized (p=0.015). No significant differences regarding IgG antibody titres were observed. Since IgA, similarly a. s IgE. antibody formation is strongly Th2 cell dependent, the results are compatible with other fmdings suggesting that RSV has an unusual propensity to activate the Th2 cell system. This may contribute to the pathological picture of bronchiolitis in small children and at the same lime render the infected child predisposed for later development of allergic sensitization. RSV bronchiolitis may thus be an important risk factor for later development of atopic disease although it cannot be excluded that the bronchiolitis simply serves as a marker that predicts later development of atopy.     

Hospitalization for RSV bronchiolitis before 12 months of age and subsequent asthma, atopy and wheeze: A longitudinal birth cohort study

Several epidemiological studies have reported recurrent wheezing and asthma in children after respiratory syncytial virus (RSV) bronchiolitis in infancy. The relationship with allergic sensitization is less clear and recent evidence suggests an interaction between atopy and RSV infection in the development of asthma. Data from a large, population-based, birth-cohort (Avon Longitudinal Study of Parents and Children) were used to compare outcomes of children according to whether or not they had been admitted to hospital in the first 12 months with RSV-proven bronchiolitis. Outcomes considered were 12-month prevalence of wheeze at two ages (between 30-42 and 69-81 months), cumulative prevalence of doctor-diagnosed asthma at 91 months and skin prick test defined atopy at 7 yr. Multivariable logistic regression models were used to calculate odds ratios for outcomes adjusted for potential confounders. A total of 150 infants (1.1% of the cohort) were admitted to hospital within 12 months of birth with RSV bronchiolitis. The prevalence of wheezing was 28.1% in the RSV group and 13.1% in controls at 30-42 months and 22.6% vs. 9.6% at 69-81 months. The cumulative prevalence of asthma was 38.4% in the RSV group and 20.1% in controls at 91 months. Atopy was found in 14.6% of the RSV group and in 20.7% of controls at 7 yr. RSV bronchiolitis was associated with subsequent wheezing between 30-42 (Odds ratio [95% CI] 2.3 [1.3, 3.9]) and 69-81 months (OR 3.5 [1.8, 6.6]) and with the cumulative prevalence of asthma at 91 months (OR 2.5 [1.4, 4.3]) but not with atopy (OR 0.7 [0.2, 1.7]). In a population-based birth cohort, RSV bronchiolitis was associated with subsequent wheezing and asthma but not with the development of atopy by age 7 yr.     

Adult asthma after non-respiratory syncytial virus bronchiolitis in infancy: Subgroup analysis of the 20-year prospective follow-up study

BACKGROUND: Recent studies have stressed the influence of other viruses than respiratory syncytial virus (RSV) in the development of asthma in later childhood after bronchiolitis in infancy. However, the virus-specific prognosis until adulthood has remained obscure, due to lack of sufficiently long follow-up studies. The aim of the present study was to evaluate adult respiratory morbidity after bronchiolitis in infancy, focused on cases not caused by RSV. METHODS: A total of 54 children hospitalized for bronchiolitis at age <2 years were re-studied at median age 19 years; 22 with RSV bronchiolitis and 22 with non-RSV bronchiolitis outside RSV epidemic were included. RSV etiology was studied by antigen and antibody assays on admission. Adult asthma was defined by two ways, based on written questionnaire, clinical examination and home peak expiratory flow monitoring. Lung function was evaluated by flow-volume spirometry (FVS), bronchial reactivity by methacholine inhalation challenge (MIC), and atopy by skin prick tests (SPT). RESULTS: In the non-RSV group, asthma by two definitions was present in 41-50% (vs 18-27% in RSV group). In logistic regression, adjusted for gender, age on admission, current atopy and smoking, non-RSV etiology of bronchiolitis, compared with RSV etiology, increased asthma risk by both strict (odds ratio [OR], 8.34; 95% confidence interval [CI], 1.18-58.69) and less strict (OR, 7.93; 95% CI, 1.14-55.41) criteria. An abnormal result in FVS was present in 32-41% and in MIC in 48-52% of cases in non-RSV and RSV groups, respectively. CONCLUSIONS: Infants with non-RSV bronchiolitis requiring treatment in hospital are at an increased risk for subsequent asthma in adulthood.     

Wheezy babies--wheezy adults? Review on long-term outcome until adulthood after early childhood wheezing.

Population-based birth cohort studies have documented that about 30% of children suffer from wheezing during respiratory infection before their third birthday. Recurrent wheezing is common in early childhood, but most patients outgrow their symptoms by school age. However, recent long-term postbronchiolitis follow-up studies from Sweden and Finland have revealed that asthma is present in about 40% of young adults and over half of the cases are relapses after many symptom-free years. In population studies, the principal predictors for later asthma have been parental asthma, recurrent wheezing, atopy and eosinophilia. In the Swedish postbronchiolitis study, atopic diathesis through the development of clinical atopy, and early passive smoking through bronchial hyper-reactivity or later active smoking led to adult asthma. The Finnish postbronchiolitis follow-up stressed early recurrence of wheezing, wheezing induced by less invasive viruses than respiratory syncytial virus (RSV), early-life atopy and eosinophilia and parental asthma as predictors for adult asthma. CONCLUSION: The majority of wheezing infants and children outgrow their symptoms by school age, but based on recent long-term follow-up studies, asthma relapses are common in young adults. These studies have highlighted parental asthma, maternal smoking and wheezing induced by other viruses than RSV as predictive factors for later asthma.     

Wheezy babies—wheezy adults? Review on long-term outcome until adulthood after early childhood wheezing

Population-based birth cohort studies have documented that about 30% of children suffer from wheezing during respiratory infection before their third birthday. Recurrent wheezing is common in early childhood, but most patients outgrow their symptoms by school age. However, recent long-term postbronchiolitis follow-up studies from Sweden and Finland have revealed that asthma is present in about 40% of young adults and over half of the cases are relapses after many symptom-free years.
In population studies, the principal predictors for later asthma have been parental asthma, recurrent wheezing, atopy and eosinophilia. In the Swedish postbronchiolitis study, atopic diathesis through the development of clinical atopy, and early passive smoking through bronchial hyper-reactivity or later active smoking led to adult asthma. The Finnish postbronchiolitis follow-up stressed early recurrence of wheezing, wheezing induced by less invasive viruses than respiratory syncytial virus (RSV), early-life atopy and eosinophilia and parental asthma as predictors for adult asthma.
Conclusion: The majority of wheezing infants and children outgrow their symptoms by school age, but based on recent long-term follow-up studies, asthma relapses are common in young adults. These studies have highlighted parental asthma, maternal smoking and wheezing induced by other viruses than RSV as predictive factors for later asthma.     

The outcome after severe bronchiolitis is related to gender and virus

The association between bronchiolitis in the first year of life and subsequent asthma, atopy, airway obstruction and bronchial hyper-responsiveness (BHR) is unsettled. Genetic predispositions, pre-morbid lung function, environmental interactions and altered immunological responses are risk factors that have been studied. The aim of this study was to assess lung function, BHR and the occurrence of asthma and atopy 11 yr after hospitalization for bronchiolitis in the first year of life, particularly focusing on the role of gender and virus involved. The study included 121 of 131 (92%) children hospitalized for bronchiolitis, 90 (74%) respiratory syncytial virus (RSV)-positive children and 141 children in an age-matched and unselected control group. At follow-up, current asthma was more common after RSV-negative bronchiolitis compared to controls (35.5% vs. 9.2%; p < 0.001), but not after RSV bronchiolitis (15.6%; p = 0.144). Higher BHR and an obstructive lung function pattern were observed after bronchiolitis, the latter most prominent after RSV-negative bronchiolitis. Higher BHR was confined to boys, but present in both the RSV-positive and RSV-negative groups (p = 0.007 and 0.003, respectively). Asthma after bronchiolitis was not associated with atopy. Atopy was similarly distributed between the RSV-positive and RSV-negative bronchiolitis groups and the control group. This study has shown that gender and type of virus are important factors to consider when addressing later development of asthma, BHR and lung function after hospitalization for bronchiolitis in early life.     

特应性体质对毛细支气管炎患儿血清糖皮质激素受体水平的影响

目的探讨特应性体质(简称特应质)对毛细支气管炎(简称毛支)患儿糖皮质激素受体(GR)表达的影响。方法采用ELISA法测定和比较毛支组(77例,包括34例特应质患儿)和肺炎组(68例)患儿血清中GRα、GRβ水平的变化。38例同期住院的非感染性小儿外科术前患儿,且无特应性及过敏性疾病家族史的患儿作为对照组。结果与对照组比较,毛支组和肺炎组中血清GRα、GRβ水平均明显升高(P0.01);毛支组血清GRα、GRβ水平高于肺炎组(P0.01)。毛支组GRα/GRβ比值较对照组和肺炎组明显升高(P0.01)。毛支组特应质和非特应质患儿血清GRα、GRβ水平与对照组比较均明显升高(P0.01);毛支组非特应质患儿GRβ水平明显高于特应质患儿(P0.01);毛支组特应质患儿GRα/GRβ比值较对照组和毛支组非特应质患儿明显升高(P0.01)。结论毛支患儿血清GRα、GRβ表达水平增强;特应质毛支患儿表现为GRα/GRβ比值增加,提示特应质毛支患儿对糖皮质激素有较高的敏感性。     

RANTES启动子-28C/G基因多态性与呼吸道合胞病毒致细支气管炎易感性的关联

目的 探讨正常T淋巴细胞表达和分泌的活性调节蛋白RANTES的启动子-28C/G基因多态性与呼吸道合胞病毒(RSV)致细支气管炎(既往称毛细支气管炎)易感的关联性.方法 应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术,检测238例RSV细支气管炎患儿及288例正常对照者的RANTES-28C/G多态性,ELISA法检测血清总IgE浓度,全自动血细胞计数仪计数嗜酸性粒细胞,并搜集受检者的特应性体质史、特应性家族史及临床相关资料.结果 RANTES-28C/G基因型分布在RSV细支气管炎组和对照组均符合Hardy-Weinberg平衡.与对照组比较,RANTES-28C/G基因型及等位基因频率在RSV细支气管炎组中的分布差异均有统计学意义(G=10.22,P＜0.01;x2=9.708,P＜0.01);与CC基因型个体相比,携带G等位基因的个体发生RSV细支气管炎的风险增加了2.09倍(OR:2.09,95% CI=1.32～3.30,P＜0.01).在RSV细支气管炎组,携带G等位基因个体具有特应性体质和特应性家族史的风险分别比CC基因型个体增加了1.85倍(OR=1.85,95% CI=1.01～3.38,P＜0.05)和1.91倍(OR=1.91,95% CI=1.03～3.54,P＜0.05),其嗜酸性粒细胞计数亦显著升高(Z=-2.303,P＜0.05).结论 RANTES启动子-28C/G基因多态性与RSV细支气管炎易感性相关联,并且-28G等位基因与RSV细支气管炎患儿的特应性体质及特应性家族史相关联.     

Ribavirin for respiratory syncytial virus bronchiolitis reduced the risk of asthma and allergen sensitization

Respiratory syncytial virus (RSV) bronchiolitis in early life is a risk factor for later development of asthma and atopy. Ribavirin is the only effective drug currently available against acute RSV bronchiolitis. However, the long-term effects of ribavirin remain unclear. We investigated a cohort of children hospitalized with RSV bronchiolitis from when they were under 2 yr old until they reached a mean age of 6.2 yr. In total, we enrolled 175 children in this study. Both the group treated with ribavirin and the group not treated with ribavirin included high-risk young children with congenital heart disease or chronic lung disease. Their respective age-matched controls, that we labeled groups A and B, both without ribavirin treatment, consisted of previously healthy subjects. Wheezing was either verified by physicians or estimated by a questionnaire. Allergen sensitization was judged by serum allergen-specific IgE levels. The cumulative incidence of physician-diagnosed asthma or recurrent wheezing in the ribavirin group (15%) was significantly lower than its incidence in the non-ribavirin-treated group (34%, p = 0.049), and in the control A group (43%, p = 0.005). Allergen sensitization was also least frequent in the ribavirin group. Ribavirin therapy was an independent factor in reducing the risk of developing asthma, asthma/recurrent wheezing, and sensitization to D. pteronyssinus / D. farinae. The long-term value of ribavirin for acute RSV bronchiolitis and its underlying mechanisms deserves further research.     

Multiple viral respiratory pathogens in children with bronchiolitis

Aim: The aim of the study was to describe the frequency of viral pathogens and relative frequency of co-infections in nasal specimens obtained from young children with bronchiolitis receiving care at a children's hospital.
Methods: We conducted a study of nasal wash specimens using real-time PCR and fluorescent-antibody assay results from children less than two with an ICD-9-CM code for bronchiolitis. All specimens were collected for clinical care at Children's Hospital in Seattle, WA, USA, during the respiratory season from October 2003 to April 2004.
Results: Viruses were detected in 168 (93%) of the 180 children with bronchiolitis. A single virus was identified in 127 (71%) children and multiple viruses in 41 (23%). Respiratory syncytial virus (RSV) was the most common virus detected (77%), followed by adenovirus (15%), human metapneumovirus (11%), coronavirus (8%), parainfluenza (6%) and influenza (1%). Of the 139 samples with RSV detected, 34 (24%) were co-infected with another viral pathogen.
Conclusion: Molecular diagnostic techniques identified a high frequency of viruses and viral co-infections among children evaluated for bronchiolitis. Further study of the role of viral pathogens other than RSV and co-infections with RSV in children with bronchiolitis appears warranted.     

A cohort of children hospitalised with acute RSV bronchiolitis: impact on later respiratory disease

This paper reviews the results from a cohort study in which 47 children hospitalised with respiratory syncytial virus (RSV) bronchiolitis and their 93 controls, matched for age, sex and place of living, were prospectively followed-up at the mean ages of 1, 3 and 7.5. Asthma was significantly more common in the RSV bronchiolitis group at all times. Asthma during the year prior to follow-up at age 7.5 was seen in 23% of the RSV children and in 2% of the controls (P < 0.001). Allergic sensitisation was found in 41% of the RSV children and in 22% of the controls (P = 0.039). When comparing these results with findings from other studies it is obvious that the rate of asthma and other bronchial obstructive symptoms are increased after RSV bronchiolitis but the various results concerning allergic sensitisation are not conclusive. Prospective studies are needed with some kind of randomised intervention against RSV before the mechanisms behind the post-bronchiolitic symptoms and the possibly increased risk for IgE mediated allergy can be settled.     

Inhaled corticosteroids during and after respiratory syncytial virus-bronchiolitis may decrease subsequent asthma

Respiratory syncytial virus (RSV) bronchiolitis in infancy can lead to bronchial hyper-reactivity or recurrent obstructive bronchitis. The aim of the present study was to determine whether the type of treatment has an influence on respiratory status after RSV bronchiolitis. The study involved 117 infants (mean age 2.6 months), who needed hospital treatment because of RSV bronchiolitis. The patients were divided randomly into three groups. All received the same symptomatic treatment. Group I children received symptomatic treatment only, group II children were treated for 7 days with inhaled budesonide, 500 µg three times per day, administered via a nebulizer. Group III children received nebulized budesonide, 500 µg twice per day for two months. Follow-up consisted of out-patient check-ups 2 and 6 months after the infection, and telephone contact two years after the infection. Statistically significant differences were seen between the groups. In group I 37% of the children had asthma, in group II 18%, and in group III 12%. According to the present study it seems that inhaled corticosteroid treatment during and after the acute phase of infant RSV bronchiolitis may have a beneficial effect on subsequent bronchial wheezing tendency.     

Eosinophil degranulation in the respiratory tract during naturally acquired respiratory syncytial virus infection.

Eosinophil cationic protein (ECP), a cytotoxic protein contained in the granules of eosinophils, has been suggested as having an important role in the pathogenesis of asthma. To determine whether ECP plays a similar role in bronchiolitis, we tested samples of nasopharyngeal secretions, obtained from a group of 47 children with various forms of illness related to respiratory syncytial virus (RSV) and from 26 children with non-RSV upper respiratory tract illness or bacterial pneumonia, for the presence of ECP by means of a double-antibody radioimmunoassay. Concentrations of ECP in children with RSV bronchiolitis were significantly higher (166.8 ng/ml) than the mean concentration of ECP in both groups of children with RSV upper respiratory tract illness (43.5 ng/ml, p less than 0.002) and RSV lower respiratory tract disease without wheezing (29.1 ng/ml; p less than 0.0002). Children with non-RSV upper respiratory tract illness or bacterial pneumonia had levels of ECP in nasopharyngeal secretions similar to those of children with RSV upper respiratory tract illness or RSV pneumonia. High ECP levels in nasopharyngeal secretions (greater than 50 ng/ml) were predictive of the development of bronchiolitis at the time of RSV infection (p less than 0.001), and the individual ECP levels correlated with severity of the disease as determined by the initial PaO2 concentrations (p less than 0.05). These data suggest that eosinophil degranulation in the respiratory tract occurs during RSV bronchiolitis and may play a significant role in the development of virus-induced airway obstruction.     

Asthma and lung function 20 years after wheezing in infancy: results from a prospective follow-up study

OBJECTIVE: To determine the outcome until adulthood after wheezing in infancy, compared with pneumonia in infancy and with controls. DESIGN: An 18- to-20-year prospective cohort study. SETTING: Pediatric department at a university hospital, providing primary hospital care for a defined population.Patients Fifty-four children hospitalized for bronchiolitis and 34 for pneumonia at younger than 2 years, and 45 controls with no early-life wheezing or hospitalization, were studied at median age 19 years. MAIN OUTCOME MEASURES: A questionnaire on asthma symptoms and medication, physical examination, flow volume spirometry (FVS), methacholine inhalation challenge (MIC), home peak expiratory flow (PEF) monitoring, and skin prick testing (SPT) to common inhalant allergens. The 2 asthma definitions were physician-diagnosed asthma and previously diagnosed asthma with recent asthmatic symptoms (physician-diagnosed asthma included). RESULTS: By the 2 definitions, asthma was present in 30% (odds ratio [OR], 3.37; 95% confidence interval [CI], 1.12-10.10) and in 41% (OR 1.38; 95% CI, 0.37-5.21) in the bronchiolitis group, in 15% (OR, 5.50; 95% CI, 1.87-16.14) and in 24% (OR, 2.07; 95% CI, 0.59-7.22) in the pneumonia group, and in 11% in the control group. After bronchiolitis, the FVS values were forced vital capacity (FVC), 108% (SD, 13%) of predicted; forced expiratory volume in 1 second, 98% (SD, 12%); forced expiratory volume in 1 second divided by FVC, 91% (SD, 7.6%); midexpiratory flow at 50% of the FVC, 74% (SD, 19%); and midexpiratory flow at 25% of the FVC, 74% (SD, 22%). Bronchial reactivity by MIC was present in 25 (48%) of 52 subjects in the bronchiolitis group, in 13 (42%) of 31 in the pneumonia group, and in 14 (32%) of 44 in the control group. The prevalence of atopy (positive SPTs) was 48% to 63% in the 3 groups. In a logistic regression adjusted for atopy and smoking, infantile bronchiolitis was an independent risk factor for asthma by both definitions. CONCLUSION: The increased risk for asthma persists until adulthood after bronchiolitis in infancy.     

Severe bronchiolitis and respiratory syncytial virus among young children in Hawaii

BACKGROUND: Lower respiratory tract infections are a leading cause of hospitalization and mortality among children worldwide. Our objective was to describe the incidence and epidemiology of severe bronchiolitis, respiratory syncytial virus (RSV), and pneumonia among children in Hawaii. METHODS: Retrospective analysis of the patient-linked hospital discharge data associated with bronchiolitis, RSV, and pneumonia among Hawaii residents younger than 5 years of age during 1997 through 2004 using the Hawaii State Inpatient Database. RESULTS: During 1997 through 2004, the average annual incidence rates for bronchiolitis, RSV, and pneumonia were 3.8, 2.7, and 6.8 per 1000 children younger than 5 years, respectively. The incidence of each condition was higher for infants younger than 1 year (15.1, 9.8, and 15.9 per 1000 infants, respectively) than the incidence for children 1-4 years of age, and higher for boys compared with girls. The incidence of each condition was highest among Native Hawaiian and other Pacific Islander children compared with children of other race groups living in Hawaii. Most hospitalizations occurred during the months of October through February. Estimated median hospital charges were $4806 (bronchiolitis), $5465 (RSV) and $5240 (pneumonia), with overall average annual charges of $11.5 million. CONCLUSION: The incidence and hospitalization rates for bronchiolitis, RSV, and pneumonia among children younger than 5 years of age in Hawaii were low; the corresponding hospitalization rates were lower than those for the general U.S. population. However, the hospitalization rates for each condition among Hawaiian and other Pacific Islander children were much higher than those for other race groups or for the U.S. population.