Risk factors associated with RSV hospitalisation in the first 2 years of life, among different subgroups of children in NSW: a whole-of-population-based cohort study

Maternal Risk Factors for Respiratory Syncytial Virus Lower Respiratory Tract Infection in Otherwise Healthy Preterm and Term Infants: A Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

To date, there is no published, formal assessment of all maternal risk factors for respiratory syncytial virus lower respiratory tract infection (RSV-LRTI) in infants. A systematic literature review and meta-analysis were undertaken to ascertain: What maternal risk factors are associated with an increased risk of RSV-LRTI in infants?

METHODS

The systematic literature review used explicit methods to identify, select and analyze relevant data. PubMed, Embase and the Cochrane Library were searched (November 2022) using terms regarding: (1) RSV/LRTI; (2) risk factors; (3) pregnant/postpartum population. Bayesian meta-analysis compared RSV hospitalization (RSVH) risk in infants born to mothers with or without certain risk factors.

RESULTS

A total of 2353 citations were assessed and 20 were included in the final review (10 individual studies; 10 pooled analyses). In 10 studies examining infants (<1 year) without comorbidities (primary outcome), 10 maternal risk factors were associated with RSV-LRTI/RSVH in multivariate analyses. Meta-analysis revealed smoking while pregnant increased infant RSVH risk by 2.01 (95% credible interval: 1.52-2.64) times, while breast-feeding was protective (0.73, 95% credible interval: 0.58-0.90). Risk scoring tools have reported that maternal risk factors contribute between 9% and 21% of an infant's total risk score for RSVH.

CONCLUSIONS

A greater understanding of maternal risk factors and their relative contribution to infant RSV-LRTI will enable more accurate assessments of the impact of preventive strategies.

Clinical Impact of Serious Respiratory Disease in Children Under the Age of 2 Years During the 2021-2022 Bronchiolitis Season in England, Scotland, and Ireland

BACKGROUND

Interventions introduced to reduce the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to a widespread reduction in childhood infections. However, from spring 2021 onwards the United Kingdom and Ireland experienced an unusual out-of-season epidemic of respiratory disease.

METHODS

We conducted a prospective observational study (BronchStart), enrolling children 0-23 months of age presenting with bronchiolitis, lower respiratory tract infection, or first episode of wheeze to 59 emergency departments across England, Scotland, and Ireland from May 2021 to April 2022. We combined testing data with national admissions datasets to infer the impact of respiratory syncytial virus (RSV) disease.

RESULTS

The BronchStart study collected data on 17 899 presentations for 17 164 children. Risk factors for admission and escalation of care included prematurity and congenital heart disease, but most admissions were for previously healthy term-born children. Of those aged 0-11 months who were admitted and tested for RSV, 1907 of 3912 (48.7%) tested positive. We estimate that every year in England and Scotland 28 561 (95% confidence interval, 27 637-29 486) infants are admitted with RSV infection.

CONCLUSIONS

RSV infection was the main cause of hospitalizations in this cohort, but 51.3% of admissions in infants were not associated with the virus. The majority of admissions were in previously healthy term-born infants.

Risk Factors and Clinical Prognosis Associated With RSV-ALRI Intensive Care Unit Admission in Children <2 Years of Age: A Multicenter Study

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections (ALRIs) in children <2 years of age. Currently, there are limited data on risk factors for very severe RSV-ALRI requiring intensive care unit (ICU) admission.

METHODS

We conducted a case-control study of children <2 years old admitted with RSV-ALRI to the Sydney Children's Hospital Network, comprising 2 large tertiary pediatric hospitals. Cases were children with laboratory-confirmed RSV-ALRI admitted to ICU, and controls were (1:2, matched on date of admission) children hospitalized with RSV-ALRI but not requiring ICU transfer. Data on risk factors were retrieved from the electronic medical record system. Adjusted odds ratios (aORs) with 95% confidence intervals (95% CI) associated with risk factors for ICU admission and the association with clinical and treatment factors were determined from logistic regression models.

RESULTS

A total of 44 (44%) of 100 cases and 90 (48.1%) of 187 controls were male. Age <6 months and preterm births were associated with a 2.10-fold (95% CI: 1.14-3.79) and 2.35-fold (95% CI: 1.26-4.41) increased risk in ICU admissions, respectively. The presence of any chronic health condition was a significant risk factor for ICU admission. The clinical presentations on admission more commonly seen in cases were apnea (aOR: 5.01, 95% CI: 1.50-17.13) and respiratory distress (aOR: 15.91, 95% CI: 4.52-55.97). Cases were more likely to be hospitalized for longer duration and require respiratory support.

CONCLUSIONS

Our results can be translated into a clinical risk algorithm to identify children at risk of very severe RSV disease.

Respiratory syncytial virus disease morbidity in Australian infants aged 0 to 6 months: a systematic review with narrative synthesis

BACKGROUND

A significant proportion of the global respiratory syncytial virus (RSV) associated morbidity is accounted for by infants aged 0 to 6 months, who are particularly vulnerable to severe disease. In 2015, 44% of global hospitalisations in infants in this age group were secondary to RSV. The objective of this systematic review is to appraise and synthesise the local evidence of RSV infection morbidity among Australian infants aged 0 to 6 months and to assess the implications for future immunisation strategies.

METHODS

Electronic databases (Medline, Embase, Pubmed and Global Health) were searched for full-text articles published between 2000 and 2023 in English language. Studies that examined markers of RSV disease morbidity in infants aged 0 to 6 months in Australia who had laboratory confirmed RSV infection were eligible for inclusion. The outcomes of interest were incidence, prevalence, testing rate, positivity rate, mortality, emergency department visits, community health visits, hospitalisation, intensive care unit admission, supplementary oxygen use, mechanical ventilation, risk factors for disease severity and monoclonal antibody use.

RESULTS

The database search identified 469 studies. After removal of duplicates and full-text review, 17 articles were eligible for inclusion. This review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Synthesis without meta-analysis guidelines.

CONCLUSIONS

Qualitative analysis of the included studies showed that Australian infants aged 0 to 6 months have higher rates of RSV testing, positivity and incidence; and more likely to develop severe disease that requires hospitalisation, intensive care unit admission or respiratory support, compared to children and adults of all ages. Aboriginal and Torres Strait Islander infants aged 0 to 6 months demonstrated higher rates of RSV infection and hospitalisation, compared to non-Indigenous infants. Age-related trends persisted in geographic areas with varying seasonal transmission of RSV, and during the SARS-CoV-2 pandemic. Passive immunisation strategies targeting infants in their first 6 months of life, either via vaccination of pregnant women or administration of long-acting monoclonal antibody during infancy, could effectively reduce RSV disease burden in Australia.

Burden of paediatric hospitalisations to the health care system, child and family: a systematic review of Australian studies (1990-2022)

Background

Paediatric hospitalisations represent a significant cost to the health system and cause significant burden to children and their families. Understanding trends in hospitalisation costs can assist with health planning and support strategies across stakeholders. The objective of this systematic review is to examine the trends in costs and burden of paediatric hospitalisations in Australia to help inform policy and promote the well-being of children and their families.

Methods

Electronic data sources (Embase, Medline, Web of Science, PSYCH-Info, CINAHL and Scopus) were searched from 1990 until December 2022. Any quantitative or qualitative studies conducted in Australian tertiary hospitals were included in the review. Eligible studies were those that included paediatric (<18 years) hospitalisations and reported on economic and/or non-economic costs for the child, family unit and/or health system. Study quality and risk of bias for each study were assessed with the Joanna Briggs Critical Appraisal Tools. We present a summary of the findings of the hospitalisation burden across major diagnostic admission categories and for the child and family unit. The systematic review was registered with Prospero (ID: CRD42021276202).

Findings

The review summarises a total of 88 studies published between 1990 and December 2022. Overall, the studies identified that paediatric hospitalisations incur significant financial costs, which have not shown significant reductions over time. In-patient direct hospital costs varied depending on the type of treatment and diagnostic condition. The costs per-case were found to range from just below AUD$2000 to AUD$20,000 or more. The financial burden on the family unit included loss of productivity, transport and travel costs. Some studies reported estimates of these costs upward of AUD$500 per day. Studies evaluating 'hospital in the home' options identified significant benefits in reducing hospitalisations and costs without compromising care.

Interpretation

Increasing focus on alternative models of care may help alleviate the significant costs associated with paediatric hospitalisation.

Funding

This research was supported by Hospitals United for Sick Kids (formerly Curing Homesickness).

Epidemiology and associated factors for hospitalization related respiratory syncytial virus infection among children less than 5 years of age in Northern Thailand

BACKGROUND

Respiratory syncytial virus (RSV) is often the main problem in young children that require hospitalization. The objective of this study was to identify factors associated with RSV-related hospitalizations in young children less than five years old.

METHODOLOGY

A retrospective study was conducted for acute respiratory tract infection (ARTI) at a tertiary care hospital from January 2017 to December 2021 by using binary logistic regression analysis to detect the associated factors with RSV-related hospitalizations in children.

RESULTS

RSV-related hospitalization was detected in 293 of 410 (71.46 %) cases of RSV infection, most of which appeared in the rainy months of August to November. The most common symptoms and signs were 81.5 % rhinorrhea, 70.7 % cough, 68.5 % sore throat, 68.3 % sputum production, and 66.8 % fever. Factors associated with RSV-related hospitalization were age less than or equal to 2 years (aOR = 4.62, 95 % CI = 1.86-11.44), preterm birth (aOR = 2.61, 95 % CI = 1.05-6.10), patients with underlying disease (aOR = 3.06, 95 % CI = 1.21-10.34), and the presenting symptoms with sputum production (aOR = 16.49, 95 % CI = 3.80-71.55). Laboratory blood tests, low levels of hematocrit (aOR = 9.61, 95 % CI = 1.09-84.49) was the associated factor for hospitalization with RSV infection (p < 0.05).

CONCLUSIONS

Factors associated with RSV-related hospitalizations in children were age less than or equal to two years, preterm birth, underlying disease, symptoms of sputum production. The low level of hematocrit was also associated with RSV-related hospitalizations in these children.

Estimated incidence of respiratory hospitalizations attributable to RSV infections across age and socioeconomic groups

BACKGROUND

Surveillance for respiratory syncytial virus (RSV) likely captures just a fraction of the burden of disease. Understanding the burden of hospitalizations and disparities between populations can help to inform upcoming RSV vaccine programs and to improve surveillance.

METHODS

We obtained monthly age-, ZIP code- and cause-specific hospitalizations in New York, New Jersey, and Washington from the US State Inpatient Databases (2005-2014). We estimated the incidence of respiratory hospitalizations attributable to RSV by age and by socioeconomic status using regression models. We compared the estimated incidence and the recorded incidence (based on ICD9-CM) of RSV hospitalizations to estimate the under-recorded ratio in different subpopulations.

RESULTS

The estimated annual incidence of respiratory hospitalizations due to RSV was highest among infants < 1 year of age with low socioeconomic status (2800, 95% CrI [2600, 2900] per 100,000 person-years). We also estimated a considerable incidence in older adults (≥ 65 years of age), ranging from 130 to 960 per 100,000 person-years across different socioeconomic strata. The incidence of hospitalization recorded as being due to RSV represented a significant undercount, particularly in adults. Less than 5% of the estimated RSV hospitalizations were captured for those ≥ 65 years of age.

CONCLUSIONS

RSV causes a considerable burden of hospitalization in young children and in older adults in the US, with variation by socioeconomic group. Recorded diagnoses substantially underestimate the incidence of hospitalization due to RSV in older adults.

Epidemiological features, risk factors and disease burden of respiratory viruses among hospitalized children with acute respiratory tract infections in Xiamen, China

Well-established surveillance and monitoring system for respiratory viruses need be improved and epidemiological data about respiratory viruses is scarce in China. This study aimed to investigate epidemiological characteristics of respiratory viruses among hospitalized children ≤ 2 years old with acute respiratory tract infections (ARTIs) in Xiamen, China from October 2014 to September 2017. The clinical records of 7248 children hospitalized for ARTIs were analyzed retrospectively. Respiratory syncytial virus (RSV) (22.3%) was the most common virus among hospitalized children ≤ 2 years old, followed by parainfluenza (5.0%), adenovirus (3.5%) and influenza (1.7%). RSV-infected children possessed a higher disease burden including higher ICU admission rate (12.7%) and hospital charges ($635.36). Especially, infants < 6 months of age had the highest risk of RSV infection (OR= 2.4, 95% CI: 1.9-2.9) and higher ICU admission rate (12.1% vs. 4.5%, 4.6%) and hospital costs ($923.3 vs. $785.5, $811.7) than other age groups. Therefore, infants aged 0-6 months, especially premature infants and children with congenital diseases, should receive more concern. There is an urgent need to develop effective immunization strategies to protect these infants through the first 6 months of life or RSV season.

Incidence and risk factors of hospitalisations for respiratory syncytial virus among children aged less than two years

The study aim was to examine the incidence and risk factors of respiratory syncytial virus (RSV) bronchiolitis hospitalisations and disease severity among infants. We compared demographic and health characteristics of children aged 0–23 hospitalised for RSV bronchiolitis (cases, n = 1227) during 2008–2018 and control children (n = 554) of the same age admitted for non-respiratory disease. RSV antigen was detected in nasal swabs by immunochromatography. Multiple logistic regression models were applied. The average annual incidence of hospitalisation for RSV bronchiolitis was 12.6 per 1000 and 1.7 per 1000 (P < 0.001) among infants and toddlers, respectively, with winter seasonality (November–March). The risk of hospitalisation for RSV bronchiolitis increased among children aged 0–5 months (OR 7.66; 95% CI 5.61–10.45) and 6–11 months (OR 12.88, 95% CI 8.48–19.55), compared to those aged 12–23 months. Additional risk factors were living in low vs. higher socio-economic status towns (OR 1.49; 95% CI 1.14–1.95), having chronic medical conditions (OR 2.75; 95% CI 1.61–4.70), birth month (October–January vs. June–September) (OR 2.19; 95% CI 1.60–2.99) and history of stay in neonatal intensive care unit at birth (OR 2.37; 95% CI 1.27–4.41). Male children and those who had pneumonia were more likely to have severe RSV bronchiolitis. In conclusion, the burden of hospitalisations for RSV bronchiolitis is high, especially in young infants. Effective preventive measures such as RSV active vaccines can reduce the risk of hospitalisations for RSV bronchiolitis among these vulnerable groups.

Transplacental transfer of RSV antibody in Australian First Nations infants

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infection hospitalisations in Aboriginal infants specifically those aged <6 months. Maternally derived RSV antibody (Ab) can protect against severe RSV disease in infancy. However, the efficiency of transplacental transfer of maternal anti-RSV Ab remains unknown in Aboriginal infants. We characterised RSV Ab in Australian First Nations mother-infant pairs (n = 78). We investigated impact of covariates including low birthweight, gestational age (GA), sex of the baby, maternal age and multiparity of the mother on cord to maternal anti-RSV Ab titre ratio (CMTR) using multivariable logistic regression model. All (n = 78) but one infant was born full term (median GA: 39 weeks, interquartile range: 38-40 weeks) and 56% were males. The mean log₂ RSV Ab titre was 10.7 (SD± 1.3) in maternal serum and 11.0 (SD ± 1.3) in cord serum at birth; a ratio of 1.02 (SD ± 0.06). One-third of the pairs had a CMTR of <1 indicating impaired transfer. Almost 9% (7/78) of the term infants had cord RSV Ab levels below <log₂ 9. Covariates showed no effect on CMTR. Further mechanistic research is needed to determine the significance of these findings on RSV disease in First Nations children.

Respiratory syncytial virus subtype circulation and associated disease severity at an Australian paediatric referral hospital, 2014-2018

AIM

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections in children and the development of vaccines to protect at-risk groups is a global priority. The aim of this study was to describe RSV subtype circulation patterns and associated disease severity to inform on potential impact of an RSV-specific prevention strategy.

METHODS

Single-centre retrospective observational study of children aged <16 years with laboratory-confirmed RSV infection from 2014 to 2018 inclusive. We described the features and frequency of all RSV subtype detections. We selected a random sample of RSV-A and RSV-B cases from each year (n = 200), described demographic and clinical features of these cases, and compared indicators of disease severity between subtypes.

RESULTS

We identified 3591 RSV detections over a 5-year period and found consistent co-circulation of subtypes with alternating predominance. Demographic and clinical characteristics were similar between children presenting with RSV-A and RSV-B infections. There was no difference in indicators of severity between the subtypes except for paediatric intensive care unit length of stay which was longer in the RSV-B group (3 vs. 5 days, P = 0.006). Respiratory co-infections were more frequent in the RSV-B group (41.8% vs. 27.4%, P = 0.035). When these were excluded there was no longer a detectable difference in paediatric intensive care unit length of stay.

CONCLUSIONS

We found co-circulation of RSV subtypes and no convincing evidence of a difference in disease severity between subtypes. RSV-specific interventions will need to be equally effective against both RSV-A and RSV-B to have the greatest impact on reducing severe RSV disease in this population.

Respiratory syncytial virus and influenza hospitalizations in Danish children 2010-2016

OBJECTIVE

To pave the way for universal or risk factor-based vaccination strategies, the present study aimed to describe the epidemiology and compare risk factors for hospitalization associated with respiratory syncytial virus (RSV) and influenza virus infections in Danish children.

METHODS

National register-based cohort study among 403,422 Danish children born 2010-2016.

RESULTS

Prior asthma hospitalization, number of children in the household, chronic disease and maternal history of asthma hospitalization were the most important risk factors for both RSV and influenza hospitalization. The incidence of influenza increased at school start.

CONCLUSIONS

Our findings enable targeted vaccination programs for high-risk children with asthma-like disease, chronic disease, siblings in the household, or maternal history of asthma hospitalization.

Respiratory syncytial virus in severe lower respiratory infections in previously healthy young Ethiopian infants

BACKGROUND

Respiratory Syncytial Virus (RSV) is the commonest cause of acute lower respiratory infections (ALRI) in infants. However, the burden of RSV is unknown in Ethiopia. We aimed to determine the prevalence, seasonality and predictors of RSV infection in young infants with ALRI for the first time in Ethiopia.

METHODS

We performed RSV immuno-chromatographic assay from nasopharyngeal swabs of infants, 29 days to 6 months of age. We included the first 10 eligible infants in each month from June 2018 to May 2019 admitted in a tertiary pediatric center. Clinical, laboratory and imaging data were also collected, and chi-square test and regression were used to assess associated factors with RSV infection.

RESULTS

Among a total of 117 study children, 65% were male and mean age was 3 months. Bronchiolitis was the commonest diagnosis (49%). RSV was isolated from 26 subjects (22.2%) of all ALRI, 37% of bronchiolitis and 11% of pneumonia patients. Although RSV infection occurred year round, highest rate extended from June to November. No clinical or laboratory parameter predicted RSV infection and only rainy season (Adjusted Odds Ratio (AOR) 10.46 [95%. C.I. 1.95, 56.18]) was independent predictor of RSV infection.

CONCLUSIONS

RSV was isolated in a fifth of young infants with severe ALRI, mostly in the rainy season. Diagnosis of RSV infection in our setting require specific tests as no clinical parameter predicted RSV infection. Since RSV caused less than a quarter of ALRI in our setting, the other causes should be looked for in future studies.

Risk factors of severe hospitalized respiratory syncytial virus infection in tertiary care center in Thailand

AIM

To determine factors associated with severe hospitalized Respiratory syncytial virus (RSV)-associated LRTI and to describe management in tertiary care center.

METHODS

Retrospective medical record review was conducted among children under 5 years old hospitalized with RSV-associated LRTI at King Chulalongkorn Memorial Hospital. Severe RSV-associated LRTI was defined as death, mechanical ventilator, or positive pressure ventilation use, prolonged hospitalization >7 days. Factors associated with severe RSV were analyzed using univariate and multivariate logistic regression.

RESULTS

From January 2011 to December 2016, 427 children were hospitalized. Median age was 10 months (IQR 4.2-23.0). One hundred seventy-four (41%) patients had severe RSV (11 deaths, 56 mechanical ventilators, 19 positive pressure ventilation, and 88 prolonged hospitalization). Factors associated with severe RSV were chronic lung disease (aOR 15.16 [4.26-53.91]), cirrhosis/biliary atresia (aOR 15.01 [3.21-70.32]), congenital heart disease (aOR 5.11 [1.97-13.23]), chemotherapy (aOR 4.7 [1.34-16.56]), and pre-term (aOR 2.03 [1.13-3.67]). Oxygen therapy was mainly low flow oxygen delivery. 88% of cases received bronchodilator. Parenteral antibiotics were prescribed in 37.9% of cases.

CONCLUSIONS

Children with co-morbidities have higher risk of severe RSV-associated LRTI. More than two-third of patients received bronchodilator, of which was not recommended by American Academy of Pediatrics. The specific treatment and prevention for RSV are urgently needed.

Accuracy of diagnostic tests for respiratory syncytial virus infection within a paediatric hospital population in Kilifi County, Kenya

Background: Respiratory syncytial virus (RSV)-induced lower respiratory tract disease is a prominent cause of hospitalisation among children aged <5 years in developing countries. Accurate and rapid diagnostic tests are central to informing effective patient management and surveillance efforts geared towards quantifying RSV disease burden. This study sought to estimate the sensitivity (Se), specificity (Sp) (along with the associated factors) and predictive values of a direct immunofluorescence test (IFAT), and two real-time reverse transcription polymerase chain reaction (rRT-PCR) assays for RSV infection within a paediatric hospital population: a multiplex rRT-PCR (MPX) and Fast-Track Diagnostics ® (FTD) Respiratory Pathogens 33 (Resp-33) rRT-PCR. Methods: The study enlisted 1458 paediatrics aged ≤59 months admitted with acute respiratory illness at the Kilifi County Hospital between August 2011 and December 2013. A Bayesian latent class modelling framework was employed to infer the tests' estimates based on the patients' diagnostic data from the three tests. Results: The tests posted statistically similar Se estimates: IFAT (93.7%, [90.7; 95.0]), FTD (97.8%, [94.6; 99.4]) and MPX (97.5%, [94.2; 99.3]). As for Sp, FTD registered a lower estimate (97.4%, [96.2; 98.2]) than MPX (99.7%, [99.0; 100.0]) but similar to IFAT (99.0%, [98.2; 99.6]). The negative and positive predictive values were strong (>91%) and closely mimicked the pattern given by the Se and Sp values respectively. None of the examined covariates (age, sex and pneumonia status) significantly influenced the accuracy of the tests. Conclusions: The evaluation found little to choose between the three diagnostic tests. Nonetheless, with its relative affordability, the conventional IFAT continues to hold promise for use in patient care and surveillance activities for RSV infection within settings where children are hospitalised with severe acute respiratory illness.

Update on current views and advances on RSV infection (Review)

Respiratory syncytial virus (RSV) infection represents an excellent paradigm of precision medicine in modern paediatrics and several clinical trials are currently performed in the prevention and management of RSV infection. A new taxonomic terminology for RSV was recently adopted, while the diagnostic and omics techniques have revealed new modalities in the early identification of RSV infections and for better understanding of the disease pathogenesis. Coordinated clinical and research efforts constitute an important step in limiting RSV global predominance, improving epidemiological surveillance, and advancing neonatal and paediatric care. This review article presents the key messages of the plenary lectures, oral presentations and posters of the '5th workshop on paediatric virology' (Sparta, Greece, 12th October 2019) organized by the Paediatric Virology Study Group, focusing on recent advances in the epidemiology, pathogenesis, diagnosis, prognosis, clinical management and prevention of RSV infection in childhood.

Association of Age at First Severe Respiratory Syncytial Virus Disease With Subsequent Risk of Severe Asthma: A Population-Based Cohort Study

OBJECTIVE

In a population-based cohort study, we determined the association between the age at first severe respiratory syncytial virus (RSV) disease and subsequent asthma.

METHODS

Incidence rates and rate ratios of the first asthma-associated hospitalization after 2 years of age in children hospitalized for RSV disease at <3 months, 3 to <6 months, 6 to <12 months, and 12-24 months of age were calculated.

RESULTS

The incidence of asthma-associated hospitalization per 1000 child-years among children hospitalized for RSV disease at <3 months of age was 0.5 (95% confidence interval [CI], .2-.7); at 3 to <6 months of age, 0.9 (95% CI,.5-1.3); at 6 to <12 months of age, 2.0 (95% CI, 1.4-2.7); and at 12-24 months of age, 1.7 (95% CI, 1.0-2.5). The rate ratio of hospitalization for asthma was 2-7-fold greater among children hospitalized for RSV disease at ages ≥6 months than that among those hospitalized for RSV disease at ages 0 to <6 months.

CONCLUSIONS

Although the burden of RSV disease is highest in children aged <6 months, the burden of subsequent asthma is higher in children who develop RSV disease at ages ≥6 months.

Birth Season and Infection Risk Among Children Under 5 Years Old: A Study of Hospital Admissions and Short Message Service-reported Symptoms at Home

BACKGROUND

The season in which a child is born may affect the immune system development and thereby influence the risk of infections. In this study, we examined the associations between birth season and the risk of hospital admission or symptoms associated with a wide range of infections.

METHODS

This study is a prospective cohort study of 2434 children with an average follow-up of 3.5 years. Admission data were obtained from the Danish National Patient Registry. Via short message service (SMS) questionnaires, 1279 families reported symptoms of infections in a 1-year period.

RESULTS

Of the 2434 children, 639 (26.3%) were admitted to the hospital, and the children experienced on average 64.4 days with symptoms of infection within 1 year. There was no association between birth season and hospital admissions due to all infectious causes [incidence rate ratio (IRR) = 0.89; 95% confidence interval (CI), 0.65-1.22; P = 0.471]. However, children born in the fall had a higher IRR for admission due to all infectious causes when excluding admissions within the first year of life. Winter- and spring-born children had lower IRRs for admission due to gastrointestinal infections than summer-born children, but this association was alone present when admissions within the first year of life were included. The short message service-survey showed significantly lower IRRs for any symptom of infection among winter-born (IRR = 0.85; 95% CI, 0.75-0.96; P = 0.009) and fall-born children (IRR = 0.88; 95% CI, 0.78-0.99; P = 0.033) in comparison with summer-born children.

CONCLUSIONS

Birth season was not associated with hospital admission due to all infectious causes within the first 5 years of age; however, fall-birth was associated with a higher IRR for admissions due to all infectious causes after the first year of life. The association between birth season and admissions due to gastrointestinal infections was only seen when including children admitted under the age of one. Being born in fall or winter was associated with a decreased IRR for number of days with any symptom of infection registered at home.

Preschool respiratory hospital admissions following infant bronchiolitis: a birth cohort study

BACKGROUND

Bronchiolitis causes significant infant morbidity worldwide from hospital admissions. However, studies quantifying the subsequent respiratory burden in children under 5 years are lacking.

OBJECTIVE

To estimate the risk of subsequent respiratory hospital admissions in children under 5 years in England following bronchiolitis admission in infancy.

DESIGN

Retrospective population-based birth cohort study.

SETTING

Public hospitals in England.

PATIENTS

We constructed a birth cohort of 613 377 infants born between 1 April 2007 and 31 March 2008, followed up until aged 5 years by linking Hospital Episode Statistics admissions data.

METHODS

We compared the risk of respiratory hospital admission due to asthma, wheezing and lower and upper respiratory tract infections (LRTI and URTI) in infants who had been admitted for bronchiolitis with those who had not, using Cox proportional hazard regression. We adjusted hazard ratios (HR) for known respiratory illness risk factors including living in deprived households, being born preterm or with a comorbid condition.

RESULTS

We identified 16 288/613 377 infants (2.7%) with at least one admission for bronchiolitis. Of these, 21.7% had a further respiratory hospital admission by age 5 years compared with 8% without a previous bronchiolitis admission (HR (adjusted) 2.82, 95% CI 2.72 to 2.92). The association was greatest for asthma (HR (adjusted) 4.35, 95% CI 4.00 to 4.73) and wheezing admissions (HR (adjusted) 5.02, 95% CI 4.64 to 5.44), but were also significant for URTI and LRTI admissions.

CONCLUSIONS

Hospital admission for bronchiolitis in infancy is associated with a threefold to fivefold risk of subsequent respiratory hospital admissions from asthma, wheezing and respiratory infections. One in five infants with bronchiolitis hospital admissions will have a subsequent respiratory hospital admission by age 5 years.

Comparisons between ethnic groups in hospitalizations for respiratory syncytial virus bronchiolitis in Israel

BACKGROUND

Ethnic disparities have been shown in respiratory syncytial virus (RSV) bronchiolitis. However, it is unclear whether such differences are related to access to care. We compared demographic and clinical characteristics of Arab and Jewish children hospitalized for RSV bronchiolitis in Israel, a country with universal health insurance.

METHODS

We reviewed the medical records of all children (n = 309) aged less than 24 months who were hospitalized with RSV between 2008 and 2011 in one medical center in Israel. Demographic, clinical, laboratory and radiological data were collected. The RSV antigen was identified using immunochromatography.

RESULTS

The annual incidence of RSV hospitalization was 5.4/1000 and 6.8/1000 among Arab and Jewish children, respectively. Arab patients were significantly younger and had significantly younger parents; most lived in low socioeconomic status towns (93.7% vs. 13.3%; p<0.001) and had more siblings (median 2 vs. 1; p = 0.01) compared to Jewish patients. Disease severity did not differ between the two ethnic groups (p = 0.3). The main predictors of severe illness were having pneumonia (adjusted odds ratio [OR] 3.86; 95% confidence intervals [CI] 1.87-7.97) and history of respiratory diseases (adjusted OR 3.89; 95% CI 1.22-12.38).

CONCLUSIONS

The incidence of hospitalizations for RSV bronchiolitis tended to be higher among Jewish than Arab children, possibly due to differences in health care utilization patterns. Differences between the Jewish and Arab patients in demographic factors likely mirror differences between the groups in the general population. Pneumonia, and not ethnicity, affected the severity of RSV bronchiolitis.