Admission trends, associated factors and the outcomes for children hospitalised to paediatric intensive care unit for asthma – A population based longitudinal study

INTRODUCTION

Asthma is one of the most prevalent non-communicable diseases in paediatric age group globally.^[1] It carries a significant risk of morbidity and mortality, especially among children and adolescents.^[2-4] Severe acute asthma is defined as an asthma exacerbation refractory to the usual therapy and accounts for up to 20% of all admissions to the paediatric intensive care unit (PICU) worldwide.^[5,6] Over the past years, the frequency of PICU admissions for acute severe asthma has shown a significant rise in many countries.^[5,6] Hospitalisation due to asthma is one of the most common ambulatory care-sensitive preventable admissions in children.^[7-9] This may reflect the failure of appropriate, timely treatment, which is a predictor of the general management of asthma in the community.

Barbados, one of the countries in the Caribbean region of the Americas, has a population of 301,865 (2021 est.), with 17.5% of the inhabitants below 15 years of age (2021 est.). The infant mortality rate is 10.23/1,000 live births; life expectancy at birth, at 78.3 years, is amongst the highest of the Caribbean islands.^[10] The literacy rate in this country is nearly 100%.^[10] The health care indicators of Barbados are at par with the developed world. The country provides free health care for all residents.^[11-13]

Barbados has one of the highest prevalences of asthma in the world, with a mean of 10,348 cases seen at the emergency clinic per year, as reported by Depradine and Lovell in 2015, and a 31.1% prevalence of recurrent wheezing amongst toddlers, as reported by Kumar et al. in 2021 for an estimated population of 284,000, including 53,000 children under the age of 16 years.^[14-16] Asthma carries significant morbidity and risk of hospitalisation in this country.^[14-19] Despite the substantial disease burden, there is no published data regarding sick asthmatic children requiring intensive care admissions from the region. A better understanding of the epidemiology and healthcare utilisation by sick asthmatic children may be useful in devising strategies to help reduce the frequency, severity, and mortality from acute severe asthma. The aim of the present study was to examine the trends in PICU admissions from acute severe asthma in Barbados and to describe the associated factors and outcome of PICU admissions from acute severe asthma.

MATERIAL AND METHODS

RESULTS

There were a total of 12708 children who presented to the emergency room (ER) at the QEH during the 5 years study period. Of those presenting to the ER, 1748 children (13.8%; 95% CI = 13.2%, 14.4%) were admitted to the paediatric wards and 101 (0.7%; 95% CI = 0.6%, 0.9%) required PICU admission due to acute asthma. During the same period there were a total of 539 admissions to the PICU. The PICU admissions for acute severe asthma accounted for 18.7% (95% CI = 15.6%, 22.3%) of the total PICU admissions. Of those requiring PICU admissions, 24 (23.8%; 95% CI = 16.1%, 33.5%) were admitted directly from the ER while the remaining 77 (76.2%; 95% CI = 66.5%, 83.9%) were transferred from the ward after worsening of their clinical condition.

Trends in the proportion of children visiting the ER for acute asthma who required PICU admission are shown in Figure 1. Analysis of the trends in the PICU admissions rate (children with acute severe asthma requiring admission to PICU/total number of children with acute asthma presenting to the emergency care service) over the 5 year study period by Chi-square test returned a value of 0.1353 (non-direction) which was not significant. Trends in the proportion of the total PICU admissions that were from acute severe asthma (PICU admissions from acute severe asthma/total number of PICU admissions) as shown in Figure 2 were also not significant (P = 0.9513).

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Figure 1:

Trends in the proportion of childhood asthma emergency room (ER) visits admitted to the paediatric general ward and the paediatric intensive care unit during 2015 through 2019 in Barbados. PICU: Paediatric intensive care unit.

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Figure 2:

Trends in the proportion of paediatric intensive care unit admissions from acute severe asthma during 2015–2029 in Barbados. PICU: Paediatric intensive care unit.

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The demographic characteristics of the study population are shown in Figure 3. Of the 101 children admitted to the PICU for acute severe asthma, 49 (48.5%; 95% CI = 38.5%, 58.6%) were children younger than 5 years and 66 (65.3%; 95% CI = 55.2%, 74.4%) were males. Amongst the 49 under-5 children admitted to the PICU for acute severe asthma, 26 (53.1%; 95% CI = 38.4%, 67.2%) children had an additional diagnosis of pneumonia. Whereas of the 24 children in the age group 10 to <15 years who were admitted to the PICU with acute severe asthma, 6 (25%; 95% CI = 10.6%, 47.1%) had an additional diagnosis of pneumonia.

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Figure 3:

Demography of children admitted to the paediatric intensive care unit and those presenting to the emergency room (ER) in Barbados. PICU: Paediatric intensive care unit.

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Past asthma history of children admitted to the PICU for acute severe asthma is shown in Table 1. Overall 22 (21.8%; 95% CI = 14.4%, 31.3%) children were previously not known to have asthma but were prescribed bronchodilator medication in the past, and 18 (17.8%; 95% CI = 11.2%, 27.0%) were previously not known to have asthma and never prescribed bronchodilator medication in the past. Past treatment characterisation of 101 children admitted to the PICU for acute severe asthma is shown in Table 2. Overall 51 (50.5%; 95% CI = 40.4%, 60.5%) were non-compliant with their inhaled corticosteroid medication, and 21 (20.8%; 95% CI = 13.6%, 30.2%) were not prescribed any inhaled corticosteroids medication.

Over all eight patients required intubation and ventilator support and there was one death in a 4-year-old child with asthma and bilateral bronchopneumonia and sepsis. Remaining 100 children admitted to the PICU for acute severe asthma during the study period were discharged from the PICU.

DISCUSSION

In this population-based study, we found that <1% of all children presenting to the ER for acute asthma required PICU admissions and a little over 5% of all hospital admissions for acute severe asthma were to the PICU. The reported proportion of the children admitted to the hospital for severe acute asthma that required PICU admission ranged from 5% to 25%.^[5,6,20] However, a more recent 2023 study from the USA reported that 1.6% of children presenting with acute asthma required PICU admission and 5.6% of all asthma admissions in children were to the PICU.^[21] These figures are similar to those of our findings in this study. Asthma being a common condition in this population, its management in the health care setting of this country is standardised and the standard of care is rigorously adhered to. Adequate standard care of children in our settings may be the reason for a lower rate of PICU admissions of children with severe acute asthma (SAA). We did not notice any trend in the PICU admissions for SAA in children in this study over the 5-year period. Increasing trends of PICU admissions for asthma as reported in some studies.^[6,20,22]

The majority of the children who required PICU admissions for the SAA were in the age group 0–<5 years and nearly two-thirds were males. Similar observations have been made in other studies.^[6,21,22] Of note nearly two third of these children had an additional diagnosis of bronchopneumonia. The role of viral respiratory infections in the exacerbation and severity of acute asthma has been well documented.^[23,24] Lung infection in children could be a trigger for acute attack of asthma and may also exaggerate the impact of the acute asthma by further compromising oxygenation and overall well-being of these children. Furthermore, infectious conditions are more common in male children compared to females.

Another notable finding from this study was that over a fifth of the children admitted to the PICU for SAA were not known to be asthmatic to their parents, although they have had medications typically used to treat asthma. Diagnosis of asthma in young children is problematic and there are distinctly different asthma phenotypes in children. Due to the complexities surrounding asthma diagnosis in young children, physicians often do not provide asthma diagnosis to younger children. However, this may have compromised the adequacy of asthma management in these children and predisposed them for SAA. This may have reflected in the finding of over half of all the children admitted to the PICU for SAA in this study were non-compliant with their inhaled corticosteroids (ICS) inhalers and history of previous hospitalisation for SAA in the past in nearly half the cases. Similar findings have been reported in other studies.^[6,25] However, recent studies have failed to support the lack of inhaled corticosteroids in the treatment or non-adherence to ICS as a risk factor for PICU admissions for SAA in children.^[25,26]

CONCLUSION

A very small proportion of children with acute asthma who present to the emergency care facility are found to have severe acute exacerbation and require paediatric intensive care support. The majority of these children are under-5 males, have had inadequate asthma treatment in the past and have been hospitalised for asthma previously. The salient findings from this seminal study of PICU admission for SAA in children make a strong case for more comprehensive study of the risk factors for the SAA in children that necessitate PICU admission and how this could be prevented.