In-Hospital Outcomes and Mortality of Pediatric Asthma Exacerbations in Thailand: A Nationwide Study (2015–2022)

Introduction

Asthma is a chronic respiratory disorder that is prevalent among children worldwide, putting a significant strain on both healthcare systems and afflicted families.¹ Despite substantial breakthroughs in diagnostic and management measures, juvenile asthma remains associated with negative outcomes such as frequent hospitalizations, poor quality of life, and, in severe cases, death.² In Thailand, asthma affects approximately 7–8% of school-age children based on national data from the International Study of Asthma and Allergies in Childhood (ISAAC), with higher rates reported in urban areas.³ Pediatric asthma exacerbations represent one of the leading causes of acute hospitalization in Thailand’s public health system.⁴

Childhood asthma prevalence varies across the globe, affected by genetic predisposition, environmental exposures, and access to healthcare.⁵ Several studies have found that hospitalizations for asthma increase the burden on health-care systems, not only via direct expenses but also through indirect consequences such as missed school days and parental work absences.^6,7 Asthma exacerbations have been extensively studied, and numerous investigations have identified various risk factors associated with these acute episodes across diverse populations.^8–13 However, comparatively few studies have investigated the factors associated with mortality among patients hospitalized from asthma exacerbation, leaving a critical gap in the literature. Understanding the determinants of mortality in hospitalized asthma patients is crucial for improving clinical outcomes, yet evidence in this area remains limited. To address this gap, the present study leverages nationwide hospitalization data from Thailand to identify predictors of in-hospital mortality in asthma. This novel approach provides a comprehensive population-level perspective and offers new insights into mortality risk factors, which can inform targeted strategies to reduce asthma-related deaths.

To our knowledge, this is the first nationwide study in Thailand to characterize the epidemiology, in-hospital outcomes, and predictors of intubation and mortality among pediatric patients hospitalized for asthma exacerbations over an eight-year period, providing population-level evidence to guide clinical practice and health policy. This study aims to determine the epidemiological trends and identify factors associated with adverse outcomes.

Materials and Methods

Study Setting and Participants

This study provided an observational retrospective study conducted on pediatric patients aged under 18 years. Data were sourced from the National Health Security Office (NHSO) of Thailand, specifically focusing on children who were hospitalized due to asthma exacerbations between January 2015 and December 2022. Thailand’s healthcare system encompasses multiple hospital levels: primary, secondary, tertiary, and private. The study included all hospitals in the NHSO system to enable a comprehensive analysis of healthcare services across different hospital types and levels in the country. The NHSO database undergoes a formal governmental auditing process prior to hospital reimbursement, which serves as a quality control mechanism; however, the possibility of ICD coding errors or inconsistencies between hospitals cannot be entirely excluded.

Each hospitalization episode is recorded as a distinct encounter in the NHSO database; patients with multiple admissions during the study period appear as separate records. Individual-level linkage across admissions was not possible due to the anonymized nature of the dataset. Patients managed exclusively in emergency department settings without subsequent inpatient admission are not captured. Important clinical confounders, including socioeconomic status, pre-admission asthma severity, controller medication use, and medication adherence, were unavailable and could not be adjusted for. While seasonal admission patterns were described, the dataset did not include individual-level environmental exposure data; therefore, causal attribution of seasonality to specific triggers was not possible.

The International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Thai Modification (ICD-10-TM) was utilized for the extraction of the data of patients with asthma exacerbations, identifying principal diagnoses as follows: J45.9 (acute asthmatic attack), and J46 (status asthmaticus). Data on children hospitalized through healthcare systems not affiliated with the NHSO of Thailand were excluded from this study. The STROBE (Strengthening the Reporting of Observational studies in Epidemiology) guideline for observational studies was utilized to report this study.¹⁴

Data Collections

Demographic data, including age, gender, month and year of admission, hospital level, hospital region, complications, length of stay (LOS), and discharge status, were collected. Participants were categorized into three age groups: under 6 years, from 6 to under 12 years, and from 12 to under 18 years. The prevalence of asthma exacerbation was presented by sex, age group, region, hospital-level differences, and month of hospitalization within a given year.

The study used ICD-10-TM to defined comorbidities as follows: 1) J18.9, J69.0, and J69.8 defined as pneumonia; 2) J96.0 defined as acute respiratory failure; 3) J30 defined as vasomotor and allergic rhinitis; 4) K21 defined as gastroesophageal reflux disease; 5) J01 defined as acute sinusitis; 6) J32 defined as chronic sinusitis; 7) E66 defined as obesity; 8) J93 defined as pneumothorax; 9) E87.6 defined as hypokalemia. The treatment outcomes of children hospitalized due to asthma exacerbation in this study encompassed requirements for intubation and in-hospital mortality. Patients needing endotracheal intubation were identified using the International Statistical Classification of Diseases and Related Health Problems 9th Revision, Thai Modification (ICD-9-TM) codes 9671, 9672, and 9604.

Several methodological limitations inherent to this retrospective administrative database study must be acknowledged. First, ICD-10-TM coding relied on clinical documentation practices that vary across hospitals and coders; miscoding or under-coding of diagnoses or complications may result in underestimation of the true burden of disease. Second, important potential confounders, including socioeconomic status, pre-admission asthma severity, controller medication use, and medication adherence, were not available in this administrative dataset and cannot be adjusted for in our regression models. Third, while seasonal admission patterns were described and attributed to environmental and epidemiological factors (monsoon season, viral triggers, and air pollution), the dataset did not include individual-level environmental exposure data; therefore, causal attribution of seasonality to specific triggers was not possible in this analysis.

Statistical Analyses

Descriptive data were summarized using counts and percentages. Chi-square or Fisher’s exact tests were applied for categorical variables as appropriate. Continuous variables were assessed for distributional normality using the Shapiro–Wilk test; non-normally distributed variables were summarized as medians with interquartile ranges and compared using the Mann–Whitney U-test. Annual mortality rates were calculated based on national population estimates and expressed per 100,000 person-years.

Univariate and multivariate logistic regression analyses were conducted to identify factors associated with endotracheal intubation. Variables for inclusion in the multivariable logistic regression model were selected based on clinical relevance and statistical significance in univariate analysis (p < 0.20 threshold), with results reported as crude and adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Mortality predictors were not modeled multivariably due to the small number of deaths, which would risk overfitting; comparisons between survivors and non-survivors are therefore descriptive. Hospital-level clustering was not adjusted for in the regression model; this represents a limitation that may affect the precision of hospital-level effect estimates. Statistical significance was defined as a p-value <0.05. All analyses were performed using Stata version 18 (StataCorp LLC, College Station, Texas, USA).

Ethics Approval

This study was approved by the Institutional Review Board of the Khon Kaen University Human Research Ethics Committee, in accordance with the Helsinki Declaration and Good Clinical Practice Guidelines (approval number HE681057). Informed consent was waived by the Ethics Committee because the dataset was fully anonymized prior to analysis; individual patients could not be identified from the data provided.

Results

Incidence of Hospitalization from Asthma Exacerbation

A total of 283,014 pediatric patients were hospitalized for asthma exacerbations in Thailand between January 2015 and December 2022. Of these, 178,061 (62.9%) were male, and 176,211 (62.3%) were younger than 6 years old. Most children received treatment at secondary-level hospitals (197,736; 69.9%), followed by tertiary hospitals (58,242; 20.6%), primary hospitals (22,314; 7.9%), and private hospitals (4,722; 1.7%). The median duration of hospitalization was 4 days with IQR of 3–5 (Table 1).

Table 1 Baseline Characteristics and Hospitalization Outcomes of Pediatric Patients Admitted for Asthma Exacerbations in Thailand, 2015–2022

Admission rates for asthma exacerbation demonstrated notable spikes in most years during the month of September, followed by August. Importantly, in 2021, overall admissions declined compared to prior years, corresponding with the extensive healthcare disruptions experienced during that period (Figure 1).

Figure 1 Monthly pediatric asthma exacerbation admissions in Thailand from 2015 to 2022.

The incidence rate of pediatric asthma exacerbation admissions ranged from 1.4 to 3.5 per 1000 population annually. During the eight-year period, the total number of hospitalizations from asthma exacerbation showed year-to-year variability, reflecting seasonal patterns and possibly changes in healthcare-seeking behavior (Table 2).

Table 2 Annual Hospitalization Incidence and In-Hospital Mortality Rates for Pediatric Asthma Exacerbations in Thailand, 2015–2022

Outcome of Asthma Exacerbation in Children

Out of the total 283,014 patients, 6452 (2.3%) required endotracheal intubation. Figure 2 depicts the distribution of intubation cases stratified by age group. Although children under 6 years accounted for the largest absolute number of intubations due to their predominance in the cohort, the adjusted odds of intubation were significantly lower in the 6–<12-year age group compared to the under-6 reference group (aOR: 0.70; 95% CI: 0.64–0.77; p<0.001), indicating that younger children carry a disproportionately higher per-admission risk of intubation. Comorbidity association with the need for intubation were pneumonia (aOR: 2.39; 95% CI: 2.21–2.59; p<0.001), pneumothorax (aOR: 101.91; 95% CI: 50.49–205.71; p<0.001), and hypokalemia (aOR: 2.78; 95% CI: 2.52–3.06; p<0.001). Children admitted to tertiary hospitals displayed significantly higher adjusted odds of intubation (aOR: 11.13; 95% CI: 9.15–13.54; p<0.001) compared to those in primary hospitals (Table 3).

Table 3 Factors Associated with Endotracheal Intubation Among Pediatric Asthma Hospitalizations in Thailand

Figure 2 Number of endotracheal intubations among hospitalized children due to asthma exacerbation in Thailand during 2015–2022 stratified by age group.

Mortality of Asthma Exacerbation in Children

Among 283,014 pediatric admissions due to asthma exacerbations, 195 in-hospital deaths were recorded, corresponding to an overall mortality rate of 0.1%. Annual mortality rates ranged from 0.11 to 0.26 per 100,000 population over the study period (Table 2). Given the small absolute number of deaths, comparisons between survivors and non-survivors should be interpreted as exploratory and hypothesis-generating.

Clinical characteristics of children who died differed significantly from those who survived. Adolescents aged 12 to <18 years accounted for a disproportionately higher proportion of deaths compared with younger age groups (23.6% vs 8.8%, p<0.001). Fatal cases were predominantly treated at tertiary-level hospitals (58.5%), which most likely reflects severity-based referral bias—patients with the most severe exacerbations are preferentially transferred to or directly admitted to tertiary centers—rather than inferior quality of care. Severe clinical complications were markedly more frequent among non-survivors, including pneumonia (45.6%), pneumothorax (8.7%), hypokalemia (39.0%), gastroesophageal reflux disease (6.2%), and obesity (4.6%) (all p<0.001). These findings indicate that fatal outcomes were significantly associated with the presence of complications, although a causal relationship cannot be established from administrative data alone (Table 4).

Table 4 Clinical Characteristics and in-Hospital Mortality Among Pediatric Asthma Exacerbation Hospitalizations

Discussion

This nationwide study provides a comprehensive overview of pediatric asthma exacerbations requiring hospitalization in Thailand and offers important insights into in-hospital outcomes, including rare but serious mortality. To our knowledge, this is the first nationwide study in Thailand to characterize these outcomes across an eight-year period using government-audited administrative data, addressing a critical gap in the LMIC pediatric asthma literature. Although the overall in-hospital mortality rate was low (0.1%), each asthma-related death represents a potentially preventable outcome and a significant public health concern. Fatal cases were characterized by severe clinical presentations and a high burden of complications, underscoring the need for early recognition and aggressive management of high-risk exacerbations.¹⁵

A key observation from this study is the disproportionate representation of adolescents among fatal asthma cases. While younger children accounted for the majority of hospitalizations, adolescents aged 12 to <18 years constituted nearly one-quarter of all deaths. Previous studies have suggested that adolescents may experience worse outcomes due to poor medication adherence, reduced caregiver supervision, delayed care-seeking behavior, and underestimation of symptom severity.¹⁶ In Thailand specifically, the absence of dedicated adolescent asthma management programs in most public hospitals, combined with peer influence and reluctance to seek medical care promptly, may further compound this risk. This pattern has been consistently observed across diverse populations, where adolescents have been identified as particularly vulnerable to fatal asthma events despite lower hospitalization rates.^17,18 These findings emphasize the importance of adolescent-focused asthma education, adherence support, and structured transition of care. Although unmeasured confounders, including socioeconomic status, medication adherence, and pre-admission asthma severity, preclude definitive causal conclusions, the large sample size and government-audited data source support the internal validity of our associations. The core risk factor patterns identified (adolescent age, severe complications, tertiary-level care) were consistent with findings from international studies across diverse healthcare settings, suggesting that our results have broader applicability to pediatric asthma management in LMICs with comparable healthcare systems.

Mortality in this cohort was strongly characterized by the presence of severe complications, including pneumonia, pneumothorax, hypokalemia, obesity, and gastroesophageal reflux disease. Pneumothorax, although rare overall, was notably overrepresented among fatal cases and reflects extreme airflow obstruction and barotrauma during severe asthma exacerbations.¹⁹ Similarly, hypokalemia—likely related to high-dose β₂-agonist therapy and critical illness—was frequently observed among non-survivors and may serve as a marker of severe disease and intensive treatment requirements. Collectively, these complications indicate that fatal outcomes occurred predominantly in the setting of life-threatening asthma exacerbations requiring advanced care.²⁰ These associations are hypothesis-generating rather than definitively causal, given that our analysis is based on administrative ICD coding without physiological severity measures such as vital signs, oxygenation parameters, or ventilation requirements. Causal statements about why these complications led to death cannot be made from these data alone. Allergic rhinitis (AR) was documented in 3.4% of surviving patients and was inversely associated with endotracheal intubation (aOR: 0.54; 95% CI: 0.43–0.67). This protective association may reflect that children with a known AR diagnosis are more likely to be engaged in regular asthma care and receive controller therapy, attenuating exacerbation severity.²¹ However, the low coding frequency of AR in this administrative dataset likely underestimates the true prevalence of atopic comorbidity, as AR is frequently managed in outpatient settings and may not be systematically recorded during acute inpatient hospitalizations.

Airway remodeling in pediatric asthma encompasses a range of structural alterations within the airways. These changes include an increase in the mass of airway smooth muscle, which may result in significant exacerbations and incomplete reversibility of airway narrowing.²² This remodeling is associated with chronic inflammation, particularly Th2-mediated responses, and may impair normal lung maturation.²³ Severe asthma in children is characterized by multiple allergen sensitizations, eosinophilic inflammation, and steroid resistance.²⁴ Current treatments, such as inhaled steroids, may not effectively address remodeling, necessitating adjunctive therapies in severe cases.²⁵ Biological therapies targeting Th2 cytokines show promise in reducing exacerbations and potentially suppressing remodeling.²³ However, the heterogeneity of pediatric severe asthma underscores the need for personalized approaches and further research using age-appropriate models to identify novel therapeutic targets.²⁶

The marked decline in asthma admissions in 2021 most likely reflects COVID-19 pandemic-related disruptions, including reduced healthcare-seeking behavior, school closures, lockdown measures that decreased respiratory virus transmission, and reduced environmental allergen exposure. While these factors may have paradoxically reduced acute exacerbation triggers, they may also have led to unmet healthcare needs and potentially worsened long-term asthma control in some patients. Regarding COVID-19 co-infection and Multisystem Inflammatory Syndrome in Children (MIS-C), our administrative dataset does not capture concurrent COVID-19 diagnoses coded separately, and MIS-C (coded as U10.9 in Thailand) was not included among the admission diagnoses in our cohort; therefore, we are unable to quantify the proportion of patients with concurrent COVID-19 or MIS-C in this study. The seasonal peaks in August and September are consistent with Thailand’s monsoon season, during which increased humidity, mold proliferation, respiratory virus circulation, and secondary aerosol formation from agricultural burning activities are recognized triggers for asthma exacerbations in Southeast Asia.^4,27,28 These environmental factors represent important modifiable targets for public health interventions aimed at reducing seasonal asthma burden, and have been associated with air pollution-related respiratory disease in the Thai context.

International guidelines established by the Global Initiative for Asthma (GINA) underscore the critical necessity of achieving not only optimal control of asthma symptoms but also working toward remission, especially within pediatric populations.²⁹ While many high-income countries report declining asthma mortality rates, a global disparity persists, with resource-limited regions still encountering avoidable deaths.³⁰ Socioeconomic factors, such as inadequate medication insurance and poor access to preventive care, amplify risks and can undercut efforts at patient and caregiver education.^2,10–12 Managing asthma in low- and middle-income countries (LMICs) presents significant challenges, particularly due to limited access to essential pharmacological treatments, especially inhaled corticosteroids (ICS).³¹ Underdiagnosis, undertreatment, and poor control are common due to poverty, air pollution, and inadequate healthcare infrastructure.³² Implementing evidence-based guidelines tailored to local needs is crucial.²¹ Strategies to improve asthma care in LMICs include enhancing access to affordable medications, educating healthcare providers and patients, and addressing socioeconomic barriers.³³ Socioeconomic disadvantage, rural residence with limited specialist access, and health literacy gaps likely contribute to the observed disparities and represent important targets for policy intervention.

This study has several important limitations. First, its retrospective observational design relies on administrative ICD-10-TM coding, which introduces the risk of diagnostic miscoding or under-coding of comorbidities and complications; this may result in underestimation of the true burden of specific conditions. Second, the NHSO database captured only inpatient hospitalizations within the NHSO network; patients managed exclusively in emergency department settings without subsequent admission, those receiving care at non-NHSO facilities, or those who died prior to hospital arrival are not captured. As a result, we were unable to assess the number of prior hospitalizations, pre-admission asthma control, or medication adherence, which are important risk factors for severe outcomes. Consequently, both hospitalization incidence and in-hospital mortality rates likely underestimate the true population-level burden of pediatric asthma exacerbations. Third, the anonymized nature of the NHSO database precluded individual-level patient linkage across admissions; therefore, we were unable to quantify prior hospitalization frequency, and patients with multiple admissions during the study period appear as independent records. Fourth, important clinical confounders, including socioeconomic status, pre-admission asthma severity, controller medication use, medication adherence, and spirometric data, were unavailable in this administrative dataset and could not be adjusted for in our analyses; unmeasured confounding may therefore influence the observed associations. Fifth, laboratory biomarkers at admission, including blood eosinophil counts, serum IgE, blood gas parameters, and inflammatory markers, were not available in the NHSO database, limiting our ability to characterize admission-level disease severity. Sixth, individual-level COVID-19 diagnosis and MIS-C status could not be identified in this cohort, as these conditions were coded separately and were not among the primary admission diagnoses included in our study population. Seventh, hospital-level clustering was not formally accounted for in the regression model, which may affect the precision of hospital-level estimates. Eighth, the small absolute number of in-hospital deaths (n=195) limits the statistical power for subgroup analyses and increases the risk of type II error; mortality comparisons should be interpreted as exploratory and hypothesis-generating. Finally, the study period includes the COVID-19 pandemic years (2020–2022), during which healthcare-seeking behavior and admission patterns were substantially altered, particularly in 2021; pandemic-era data should therefore be interpreted with this contextual caveat in mind.

Conclusion

This nationwide eight-year analysis of pediatric asthma hospitalizations in Thailand revealed a low but clinically meaningful overall in-hospital mortality rate, with fatal outcomes significantly associated with adolescent age, tertiary-level care, and severe complications including pneumonia, pneumothorax, and hypokalemia, which functioned as both markers of disease severity and potential contributors to death. Adolescents represented a particularly vulnerable subgroup requiring age-specific adherence support and dedicated transition-of-care programs. Thailand’s near-universal NHSO health coverage infrastructure offers an important structural platform for delivering equitable, risk-stratified asthma care across all hospital levels, and future prospective studies incorporating clinical severity measures, biomarkers, and longitudinal adherence data are needed to validate the hypothesis-generating associations identified here.