Sociodemographic differences in long-term survival among children and young people with life-limiting conditions: A 10-year cohort analysis using national health insurance data

Abstract

Background

Children and young people (CYP) with life-limiting conditions (LLCs) comprise a clinically heterogeneous population with diverse disease trajectories and survival patterns. However, studies evaluating long-term survival according to disease group and sociodemographic characteristics remain limited.

Objectives

We assessed long-term survival patterns among CYP with LLCs and evaluated differences in mortality outcomes according to disease group and selected sociodemographic characteristics.

Design

Cohort study.

Methods

Using the Korean National Health Insurance database, we identified individuals aged 0–24 years who were newly diagnosed with LLCs between 2011 and 2013. Patients were followed from the date of diagnosis until death or December 31, 2020. Kaplan–Meier survival analyses and Cox proportional hazards models were used to evaluate long-term mortality outcomes according to disease groups and sociodemographic indicators, including insurance premium-based income categories and residential area.

Results

In total, 175,813 CYP with LLCs were included. Survival patterns differed significantly across disease groups, age groups, and income levels. Disease group distribution varied by age, with premature and neonatal conditions predominating in infancy. Survival probabilities were lowest among children aged < 1 year and among medical aid beneficiaries. Premature and neonatal disorders and cardiovascular diseases were associated with the shortest observed survival durations. Male patients demonstrated a higher hazard of death from cancer (hazard ratio [HR] 1.83), metabolic diseases (HR 1.61), and neurologic and neuromuscular diseases (HR 1.33) compared to female patients. Higher hazard ratios among medical aid beneficiaries were observed primarily in patients with metabolic, neurologic and neuromuscular diseases, whereas residence-related differences in survival were observed among patients with cardiovascular diseases.

Conclusion

Distinct survival trajectories exist across disease groups among CYP with LLCs. Early mortality predominates in premature and neonatal disorders and cardiovascular diseases, whereas more prolonged survival patterns are observed in cancer and neurologic disorders. These findings may inform the development of disease-specific integrated treatment strategies, long-term care planning, and supportive care policies for CYP with LLCs and their families.

Plain Language Summary

Children and young people with life-limiting conditions often live with severe illnesses that require ongoing medical care and support. These conditions include cancer, neurologic disorders, heart disease, respiratory disease, metabolic disorders, and severe neonatal conditions. Some children die soon after diagnosis, while others survive for many years with complex healthcare needs. Understanding these survival patterns is important for planning treatment, supportive care, and pediatric palliative care services. In this study, we used national health insurance data from Korea to examine long-term survival among 175,813 children and young people aged 0–24 years who were diagnosed with life-limiting conditions between 2011 and 2013. We followed patients for up to 10 years after diagnosis. Survival differed greatly depending on the type of disease. Children with premature and neonatal conditions or cardiovascular diseases had the shortest survival times, with many deaths occurring within the first year after diagnosis. In contrast, children with neurologic disorders and cancer often survived for longer periods after diagnosis. Survival was also lower among infants younger than 1 year and among children from lower-income families receiving medical aid support. In some disease groups, boys had a higher risk of death than girls. Regional differences were generally small, although children with cardiovascular diseases living outside metropolitan areas had poorer survival outcomes. These findings show that children and young people with life-limiting conditions have different healthcare and support needs depending on their disease and social circumstances. The results may help improve long-term care planning, supportive services, and healthcare policies for affected children and their families.

Introduction

Life-limiting conditions (LLCs) are characterized by a shortened life expectancy and substantial healthcare needs.^1,2 They include neonatal diseases and cancer, as well as cardiovascular, metabolic, neurological, and other chronic conditions. Children and young people (CYP) with LLCs often require intensive treatments, including advanced medical technologies, leading to frequent healthcare utilization and long-term medical support.^1,3 Even with prolonged survival, many CYP experience severe illness and persistent medical fragility. Therefore, pediatric palliative care services are often required throughout the disease trajectory, extending beyond end-of-life care.^1,4

Treatment failure or discontinuation in CYP with LLCs often results in death. However, LLCs comprise a clinically heterogeneous group of conditions characterized by shortened life expectancy and uncertain, variable disease trajectories. ⁵ Some CYP experience rapid deterioration and early death, whereas others survive for prolonged periods with complex healthcare needs, persistent medical fragility, and repeated healthcare utilization.^1–3 International pediatric palliative care frameworks emphasize that CYP with LLCs require long-term, multidisciplinary, and trajectory-informed care planning rather than services focused solely on end-of-life management. Consequently, understanding long-term survival patterns is essential to optimize prognostic assessments, pediatric palliative care delivery, direct healthcare resource allocation, and improve long-term service planning for CYP with LLCs and their families.^1,4

However, predicting outcomes in CYP with LLCs is clinically challenging. Several factors complicate survival prediction, including the rarity and heterogeneity of these conditions, advances in medical technologies that improve survival, and the presence of unexpected long-term survivors despite poor prognostic expectations, who are frequently observed in pediatric populations. ² Therefore, improved understanding of long-term survival characteristics among CYP with LLCs may support the development of evidence-based treatment strategies, integrated care pathways, and supportive healthcare policies.

A cohort study in the United Kingdom reported that children with LLCs were 75% more likely to die in the pediatric intensive care unit (PICU) compared to those without LLCs. In a previous study, the 1-year survival rate among children with LLCs was high (93%); however, 73% of all PICU deaths occurred in children with LLCs. ³ In the Republic of Korea, government policies have targeted improvements in CYPs’ health outcomes. The infant mortality rate decreased from 3.2 per 1,000 live births in 2010 to 2.5 in 2020, and has continued to decline. The mortality rate from childhood cancer was reported to be 3.43 per 100,000 person-years; however, the mortality rate among CYP with LLCs was 9.3 per 100,000 population in 2015, increasing to 82.7 per 100,000 population among children aged < 1 year.^6,7 Recent studies have emphasized socioeconomic disparities in pediatric cancer survival and critical illness outcomes. Children from socioeconomically disadvantaged backgrounds exhibit poorer survival outcomes across multiple pediatric disorders, including childhood cancer.^8,9 Previous studies imply that inequalities in pediatric health outcomes may persist across different healthcare systems; however, the magnitudes and underlying mechanisms of these differences vary according to national healthcare structures and social support systems.^9,10 To our knowledge, no study has evaluated long-term survival trends among CYP with LLCs in Korea, nor has any study assessed differences in survival outcomes according to disease characteristics and sociodemographic factors.

In our study, National Health Insurance (NHI) data were used to evaluate long-term survival patterns among CYP with LLCs in Korea. In particular, we identified differences in survival trajectories according to disease group and sociodemographic characteristics, including age, sex, income level, and residential area. By evaluating long-term survival patterns and mortality outcomes across heterogeneous LLC groups, we sought to provide population-level evidence relevant to prognostic assessment, pediatric palliative care planning, transition support, healthcare resource allocation, and the development of disease-specific supportive care strategies for CYP with LLCs.

Methods

Data source and study population

The study population was derived from CYP with LLCs as identified in the National Health Information Database from the National Health Insurance Service (NHIS), Korea’s single insurance provider. As of the end of 2022, the NHIS insured 50 million people, covering 97.1% of the population. ¹¹ Therefore, the study population was considered representative of the real-world Korean population.

Our study included LLC patients aged ≤ 24 years who received care in medical and health institutions, excluding dental clinics, traditional Korean-medicine clinics, and pharmacy-based services. Patients registered in the NHIS database with incident diagnoses between January 1, 2011, and December 31, 2013, were included. A washout period between January 1, 2008, and December 31, 2010, was applied. Participants were followed from the date of the first LLC diagnosis until death or December 31, 2020, whichever occurred first. Individuals who did not die during the study period were right-censored at the end of follow-up. To minimize incomplete follow-up, individuals without annually linked eligibility data, including date of birth, sex, age, and residential area, were excluded at cohort entry. Therefore, loss to follow-up due to insurance eligibility discontinuity was minimal. Details on the patient-selection process were provided in a previous report. ¹² The final study population consisted of 175,813 patients. Considering the use of a nationwide, retrospective cohort derived from the NHI database, all individuals meeting the predefined inclusion criteria during the study period were included. Therefore, no a priori sample size calculation was performed.

Life-limiting conditions and outcomes

The definition of a LLC was based on previously published LLC classifications by Kim et al., which were adapted from the Directory of LLCs to reflect the Korean context (Supplementary Table 1).^7,12,13 Diagnoses were coded using the Korean Standard Classification of Diseases (KCD), 6^th edition, a Korean modification of the International Classification of Diseases (ICD), 10^th revision. The KCD is a national modification of the ICD, which is part of the World Health Organization Family of International Classifications (WHO-FIC). Individuals were identified as having an LLC if an LLC-related diagnosis code was recorded in the primary diagnosis field or any of the first five additional diagnosis fields. Subsequently, eligible individuals were classified into 1 of 10 LLC diagnostic groups. Group assignment was determined according to the temporal priority of diagnoses recorded between 2011 and 2013. For claims containing multiple LLC diagnoses, diagnostic priority was assigned sequentially from the primary diagnosis to the fifth additional diagnosis code.

Variables

Age was categorized as < 1 year and 5-year intervals thereafter. Income levels, based on percentiles of the NHI premium, were categorized into four groups: medical aid beneficiaries, low income (bottom quartile), middle income (second to third quartiles), and high income (top quartile).^7,12 Medical aid beneficiaries represent individuals receiving government-supported public assistance for healthcare costs and were classified separately from premium-based income categories. Residence was classified as metropolitan or non-metropolitan, with metropolitan areas, including major cities as designated administratively by the Korean government (Seoul, Busan, Daegu, Incheon, Gwangju, Daejeon, Ulsan, and Sejong). Variables included in the analyses were selected a priori based on previous studies regarding prognostic and sociodemographic factors, as well as the availability of variables within the NHI database.^7,10,14,15

Statistics analysis

Categorical variables are presented as numbers and percentages. Kaplan–Meier survival curves and weighted log-rank tests were used to evaluate survival patterns according to cancer status, disease group, age group, and income level.^16,17 Weighted log-rank tests were selected because several survival curves exhibited non-proportional patterns and crossing hazards during follow-up. Cox proportional hazards regression models were used as the primary time-to-event analytical approach to evaluate long-term mortality while accounting for variable follow-up durations and censoring. Hazard ratios (HRs) and 95% confidence intervals (CIs) were reported. Age was excluded from the Cox proportional hazards models because the proportional hazards assumption was violated. Therefore, age-specific survival patterns were additionally investigated using Kaplan–Meier analyses stratified by age group. Separate univariable Cox proportional hazards analyses were independently conducted within each LLC category to evaluate associations between sociodemographic factors and long-term mortality outcomes descriptively. In addition, univariable logistic regression analyses were performed as supplementary descriptive analyses to compare overall mortality status across sociodemographic and disease groups. Crude odds ratios (ORs) and 95% CIs were reported. Survival duration was descriptively summarized according to disease group. Statistical analyses were performed using R statistical software (v3.6.3; R Core Team, Vienna, Austria) and SAS v. 9.4 (SAS Institute, Cary, NC, USA). A two-tailed significance level of α = 0.05 was applied for all tests.

Results

Table 1 presents the sociodemographic and clinical characteristics of the CYP with LLCs. Among the 4,408 deaths observed by December 31, 2020, males accounted for 60.1% of cases, representing a higher proportion than females. Deceased patients were more frequently observed in the < 1-year and 20–24-year age groups. A higher proportion of deceased patients had cancer and cardiovascular diseases, whereas a lower proportion was observed in the high-income group. Most of the patients (96.6%) had a single LLC diagnosis during the study period (data not shown). The distribution of disease groups varied substantially across age groups at both cohort entry and death during follow-up (Supplementary Table 2). Premature and neonatal conditions predominated in infancy, whereas cancer accounted for a greater proportion of cases and deaths in older age groups.

Table 1.

Sociodemographic and clinical characteristics of children and young people (CYP) with life-limiting conditions (LLCs).

Characteristics	Overall (N=175,813)		Deaths (N=4,408)
	n	%	n	%
Sex
Male	93,399	53.12%	2,650	60.12%
Female	82,414	46.88%	1,758	39.88%
Age group
<1	27,403	15.59%	1,201	27.25%
1–4	24,638	14.01%	602	13.66%
5–9	16,331	9.29%	286	6.49%
10–14	22,418	12.75%	436	9.89%
15–19	38,718	22.02%	840	19.06%
20–24	46,305	26.34%	1,043	23.66%
Income levels
Medical aid	7,949	4.52%	304	6.90%
Low	25,948	14.76%	645	14.63%
Middle	77,336	43.99%	2,085	47.30%
High	58,365	33.20%	1,239	28.11%
Missing	6,215	3.54%	135	3.06%
Residence
Non-metropolitan	97,313	55.35%	2,457	55.74%
Metropolitan	78,079	44.41%	1,936	43.92%
Missing	421	0.24%	15	0.34%
Cancer presence
Cancer	31,332	17.82%	1,396	31.67%
Non-cancer	144,481	82.18%	3,012	68.33%
Disease group
Neurological and neuromuscular	30,925	17.59%	764	17.33%
Cardiovascular	15,324	8.72%	581	13.18%
Respiratory	27,397	15.58%	490	11.12%
Renal and urological	22,889	13.02%	340	7.71%
Hematological or immunological	7,396	4.21%	151	3.43%
Metabolic	7,876	4.48%	127	2.88%
Other congenital or genetic defect	7,603	4.32%	125	2.84%
Cancer	31,332	17.82%	1,396	31.67%
Premature and neonatal	7,567	4.30%	257	5.83%
Gastrointestinal	17,504	9.96%	177	4.02%

LLC, life-limiting condition.

Income levels were based on percentiles of the National Health Insurance premium and categorized as medical aid, low (bottom quartile), middle (second to third quartiles), and high (top quartile).

Residence was classified as metropolitan or non-metropolitan, with metropolitan including major metropolitan cities designated administratively by the Korean government (Seoul, Busan, Daegu, Incheon, Gwangju, Daejeon, Ulsan, and Sejong).

Figure 1 presents Kaplan–Meier survival curves stratified by disease type, age group, and income level. The 1-, 5-, and 10-year survival probabilities after diagnosis of an LLC were 0.987, 0.979, and 0.974, respectively (data not shown). Survival curves demonstrated clear temporal differences according to disease type (Figure 1(a) and (b)). The survival curves for cancer and non-cancer patients crossed at approximately 1 year after diagnosis; thereafter, survival remained consistently higher in the non-cancer group (Figure 1(a)). Compared to premature and neonatal disorders and cardiovascular diseases, several chronic disease groups, including neurologic and neuromuscular disorders and cancer-related LLCs, exhibited relatively prolonged survival trajectories throughout follow-up (Figure 1(b)). When stratified by age and income level, survival probabilities were lowest among children aged < 5 years, particularly those aged < 1 year, and among patients classified as medical aid beneficiaries (Figure 1(c) and (d)).

Figure 1.

Kaplan-Meier curves based on potential factors in children and young people (CYP) with life-limiting conditions (LLCs).

Disease classification, age, and income levels at the initial diagnosis of LLC. Income levels are based on the percentiles of the National Health Insurance premium: medical aid; low (bottom quartile); middle (second to third quartile); and high (top quartile). Weighted log-rank test. Shaded areas indicate 95% confidence intervals

Table 2 summarizes the results of Cox proportional hazards models evaluating long-term mortality outcomes according to disease group and sociodemographic factors. In cancer, metabolic diseases, and neurologic and neuromuscular disorders, male patients exhibited higher hazards of death compared to female patients (HR 1.83, 95% CI 1.64–2.04; HR 1.61, 95% CI 1.11–2.34; and HR 1.33, 95% CI 1.15–1.54, respectively). In metabolic and in neurologic and neuromuscular diseases, hazards of death were higher among medical aid beneficiaries than among the high-income group. Residential region was not significantly associated with survival in most disease groups; however, patients with cardiovascular diseases residing in non-metropolitan areas had higher hazards of death than did those residing in metropolitan areas. Figure 2 illustrates differences in observed survival duration according to disease group. Survival duration from diagnosis to death was shortest among CYP with premature and neonatal disorders, and cardiovascular diseases, whereas longer survival durations were observed among those with neurologic and neuromuscular disorders.

Table 2.

Long-term survival analysis between demographic characteristics and death risk in CYP with LLCs by disease group.

​	HR (95% CI)
	Neurologic and neuromuscular (Deaths=764)	Cardiovascular (Deaths=581)	Respiratory (Deaths=490)	Renal and urologic (Deaths=340)	Gastrointestinal (Deaths=151)	Hematologic or immunologic (Deaths=127)	Metabolic (Deaths=125)	Other congenital or genetic defect (Deaths=1,396)	Cancer (Deaths=257)	Premature and neonatal (Deaths=177)
Sex
Male	1.33 (1.15–1.54)	1.04 (0.88–1.23)	1.58 (1.31–1.92)	1.27 (1.02–1.58)	1.46 (1.08–1.97)	1.04 (0.75–1.45)	1.61 (1.11–2.34)	0.98 (0.69–1.41)	1.83 (1.64–2.04)	0.90 (0.70–1.16)
Female (Reference)	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Income level
Medical aid	2.97 (2.35–3.76)	1.42 (0.88–2.29)	2.56 (1.77–3.70)	2.25 (1.50–3.38)	2.39 (1.34–4.28)	1.33 (0.56–3.12)	3.45 (1.67–7.14)	0.68 (0.16–2.81)	1.10 (0.85–1.43)	1.32 (0.32–5.39)
Low	1.12 (0.87–1.44)	1.26 (0.96–1.65)	1.33 (1.00–1.75)	1.41 (1.01–1.97)	1.48 (0.92–2.39)	0.94 (0.53–1.64)	1.78 (1.00–3.18)	1.52 (0.86–2.69)	1.07 (0.91–1.25)	1.16 (0.75–1.78)
Middle	1.57 (1.31–1.88)	1.40 (1.15–1.71)	1.20 (0.97–1.48)	1.56 (1.20–2.02)	1.75 (1.20–2.53)	1.35 (0.93–1.96)	1.67 (1.06–2.61)	1.22 (0.81–1.84)	1.09 (0.97–1.23)	1.01 (0.76–1.36)
High (Reference)	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Residence
Non-metropolitan	1.08 (0.94–1.25)	1.36 (1.15–1.62)	0.87 (0.72–1.04)	1.22 (0.98–1.52)	1.17 (0.87–1.58)	0.86 (0.62–1.20)	0.75 (0.53–1.07)	1.14 (0.80–1.64)	0.93 (0.83–1.03)	0.95 (0.74–1.23)
Metropolitan (Reference)	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00

HR, hazard ratio; CI, confidence interval. Income levels were based on percentiles of the National Health Insurance premium and categorized as medical aid, low (bottom quartile), middle (second to third quartiles), and high (top quartile).

Residence was classified as metropolitan or non-metropolitan, with metropolitan including major metropolitan cities designated administratively by the Korean government (Seoul, Busan, Daegu, Incheon, Gwangju, Daejeon, Ulsan, and Sejong).

Hazard ratios were estimated from separate univariable disease-specific Cox proportional hazards analyses conducted independently within each LLC category.

Figure 2.

Duration of survival from onset in CYP with LLCs.

LLC, life-limiting conditions. Neuro, Neurologic and Neuromuscular; Cardio, Cardiovascular; Respiro, Respiratory; Renal/Uro, Renal and Urologic; Gastro, Gastrointestinal; Hemato/Immuno, Hematologic or Immunologic; Congen/Gene, Other Congenital or Genetic defect; Pre/Neonatal, Premature and Neonatal. Error bars indicate 95% confidence intervals.

Supplementary univariable logistic regression analyses (Supplementary Table 3) demonstrated that male patients had higher odds of death compared to female patients (OR 1.34, 95% CI 1.26–1.42). Patients diagnosed at < 1 year of age had higher odds of death compared to those aged 20–24 years, while medical aid beneficiaries had higher odds of death than the high-income group. No statistically significant differences in mortality odds were identified according to residential status. Disease-related variation in mortality outcomes was observed. Compared to gastrointestinal diseases, higher odds of death were observed in cancer and cardiovascular diseases, premature and neonatal conditions, neurologic and neuromuscular disorders, and hematologic and immunologic diseases.

Discussion

We utilized data from the NHIS to examine the long-term survival characteristics of CYP with LLCs. Survival duration varied significantly depending on the disease type. Post-diagnosis, CYP in the neurological and neuromuscular diseases group had the longest survival times, and CYP in the premature and neonatal diseases group had the shortest. Factors that increased the risk of death within each disease group were also identified. Compared to patients with other diseases, those with cardiovascular or premature and neonatal diseases had a high probability of death by approximately 1 year after the initial diagnosis, after which the survival curves became stable. In contrast to several non-cancer LLC groups, which demonstrated relatively early stabilization of survival trajectories after diagnosis, cancer-related LLCs demonstrated a more prolonged decline in survival over time. This pattern may reflect the chronic, relapsing, and often progressive clinical course commonly observed in pediatric cancers.

In a study involving children admitted to the PICU, the 1-year survival rate for those with LLCs was 93%, with most deaths occurring within the first 3 months. ³ Similarly, we found that among CYP diagnosed with LLCs, excluding those with cardiac, cancer, and neonatal diseases, the majority of deaths also occurred within 3 months post-diagnosis (Figure 1(b)). Previous research on the characteristics of children with severe illnesses in South Korea showed that deaths in this population accounted for approximately one-third of total pediatric mortality. ¹⁸ While mortality rates in other age groups are declining, infant mortality in Korea has not decreased. For children in Korea, the age-standardized cancer incidence rate according to the international classification of childhood cancer has shown an upward trend over the past decade: 155.0 per 1,000,000 in 2011 and 157.0 per 1,000,000 in 2021.^19,20 In CYP with LLCs, the prognosis can be difficult to predict and the types of services required may vary. These challenges can be addressed by an awareness of the characteristics associated with the risk of death in CYP with LLCs and disease stratification according to those characteristics.

Although survival outcomes among CYP with LLCs in Korea appeared relatively favorable in our cohort, previous studies have suggested that improvements in pediatric survival may partly reflect advances in medical technology, intensive care, and disease-specific treatment strategies.^18,21 Advances in pediatric critical care, oncologic therapy, and neonatal care have contributed to improved survival outcomes among children with severe illnesses in Korea and other high-income countries.^22,23 Despite this, survival differed depending on the presence of cancer. After the initial LLC onset, the survival rates of patients with non-cancer diseases declined sharply within approximately 1 year, while the survival of cancer patients followed a continuous decline, with a lower probability extending within 5 years. For patients 0–18 years of age with childhood cancer, the relative survival rates had an increasing trend, from 77.3% in 2006–2010 to 86.5% in 2017–2021 for the 5-year relative survival rate, and from 75.2% in 2006–2010 to 81.8% in 2012–2016 for the 10-year relative survival rate. ²⁰

In Korea, CYP with LLCs typically have a high survival rate and a very long remaining lifespan. The trajectory of the dying process in pediatric patients varies depending on the disease type, with the most common trajectories being sudden death, fluctuating decline, and constant medical fragility.^24,25 Unlike adults, who experience a steady decline, this pattern is rarely the case in children. In addition, CYP with LLCs face a much broader spectrum of disease stages in the end-of-life process than is the case in adults. The disease-specific characteristics of death in these patients and the factors that influence these outcomes should therefore be taken into account in managing CYP with LLCs.

As medical advancements continue to decrease mortality rates, for CYP with LLCs the focus must include not only survival-related factors but also the provision of high-quality care during the survival period. However, research into the survival and healthcare utilization patterns of CYP with LLCs in Korea remains limited. Furthermore, prior studies have highlighted the significant financial burden that healthcare imposes on the families of CYP with LLCs.^7,12,26–28 The establishment of long-term, time-series data is needed to evaluate survival-related factors and to develop evidence-based, tailored integrated service programs for CYP with LLCs.

There were no differences in long-term survival outcomes according to residence, with the exception of cardiovascular diseases, for which the risk of death was higher in non-metropolitan areas (HR = 1.36). This may reflect the fact that the regional cardiocerebrovascular centers designated by the Ministry of Health and Welfare are located primarily in large cities. ²⁹ Given the nature of cardiovascular diseases, in which there is a limited, critical period for intervention, geographical accessibility may influence outcomes. In addition, the characteristics of cardiovascular diseases may be important factors affecting outcomes in CYP with cardiovascular disease. ³⁰ A recent study found that, since the 1980s, regional disparities in CVD death rates have significantly decreased in Korea, although the burden remains high in some areas. ³¹ However, it is important to note that most of these trends were determined in middle-aged and elderly populations, whereas research specifically targeting CYP is limited. Although socioeconomic disadvantage and regional residence are often interrelated, the absence of significant regional differences across most disease groups may partly reflect Korea’s near-universal NHI coverage system and the broad categorization of residence into metropolitan and non-metropolitan areas used in our study. Our results also show that for CYP with neurological, respiratory, general, urologic, gastrointestinal, and metabolic diseases, mortality risks were higher in medical aid recipients than in the high-income group. For CYP with cancer, mortality outcomes did not differ significantly by income level when compared to the high-income group. The Korean government operates a medical expense support program for pediatric cancer patients whose families are in the medical aid and second-lowest income brackets, defined as an income < 50% of the standard median income. Moreover, for patients receiving medical aid, the survival probability curve based on long-term trends over 10 years revealed sharply diverging survival probabilities after 2–3 years, with a significant decline in the survival probability at 5 and 10 years. This implies that, once support for non-covered medical expenses is no longer available, it becomes increasingly difficult to bear the associated costs.

Previous studies have emphasized socioeconomic disparities in pediatric cancer survival and critical care outcomes. A systematic review demonstrated that lower socioeconomic status was associated with poorer survival among children with cancer, particularly in low- and middle-income countries; however, disparities have been observed in high-income countries. ⁸ Subsequent studies have suggested that socioeconomic status may partly contribute to racial and ethnic disparities in childhood cancer survival, and that inequalities related to race, ethnicity, socioeconomic status, insurance coverage, and geographical accessibility persist in pediatric critical care and cancer outcomes.^9,10,32,33 Notably, socioeconomic disparities in childhood cancer survival have been reported in countries with universal healthcare systems, including the United Kingdom and the Nordic countries.^32,33 In contrast, the socioeconomic gradient observed in our study appeared less pronounced, particularly among patients with cancer. This finding should be interpreted with caution. Korea’s near-universal NHI coverage and disease-specific financial support programs may reduce some access-related barriers; however, direct international comparisons remain challenging because studies differ in terms of healthcare systems, socioeconomic indicators, disease definitions, and analytic approaches.

We found that the risk of death was higher among male CYP with neurological and neuromuscular disorders, respiratory diseases, and cancer-related LLCs. Several studies have reported sex-based differences in mortality outcomes for these diseases.^34–36 Even in the absence of death, male CYP experience greater vulnerability, as reflected in elevated morbidity and hospitalization rates.^37,38 In particular, the male predominance observed in some neurological and neuromuscular disorders may partly reflect the higher prevalence of X-linked disorders among males. Although the mechanisms underlying sex-based differences in disease progression remain uncertain, biological, genetic, and disease-specific factors may contribute to differences in survival outcomes between males and females.

This study had several strengths. First, we used NHI data to assess the long-term survival trends of CYP with LLCs. By constructing a cohort from LLC onset until death caused by the LLC, our findings provide meaningful insights into the characteristics of this patient population. Second, survival differences based on the type of LLC were explored by investigating the disease characteristics. This approach may serve as a foundation for developing personalized care plans tailored to the specific characteristics of the diseases affecting CYP. In addition, by evaluating disease-specific prognoses according to sex, region, and income level, we identified key factors associated with the prognosis for each disease, which may inform the development of public-health policies.

However, our study has several limitations. First, only patients with LLCs were included, precluding comparisons with the general population. Second, due to limitations of the administrative data source, disease stage or severity at diagnosis, genetic factors, and other clinical characteristics that can influence mortality could not be evaluated. In addition, age was excluded from the Cox proportional hazards models because the proportional hazards assumption was violated. Although age-stratified Kaplan–Meier analyses were performed, exclusion of age from the multivariable Cox models may have influenced the interpretation of HR estimates. Furthermore, the observed survival patterns should be interpreted in the context of the heterogeneous age-specific distribution of disease groups. In addition, because children, adolescents, and young adults were analyzed within a broader CYP framework, age-specific clinical trajectories and care patterns remain uncertain. Sociodemographic characteristics were assessed using proxy indicators based on insurance premium-derived income categories and residential area. These measures may not have captured broader dimensions of socioeconomic disadvantage, such as parental education, employment status, insurance status, or area-level deprivation. Finally, residual confounding due to unmeasured clinical and social factors may have influenced the observed associations. In addition, several disease groups had relatively small numbers of deaths, which may have limited statistical power.

Conclusion

We evaluated long-term survival characteristics among CYP with LLCs and identified significant prognostic differences according to disease characteristics. We observed differences in survival outcomes associated with demographic factors such as sex, income level, and area of residence. These findings may inform the development of tailored, integrated treatment and care policies for this population.

With its advanced critical care infrastructure, Korea has achieved relatively low pediatric mortality rates. However, vulnerable groups and gaps in care coverage persist, emphasizing the need for targeted treatment and support. Providing focused care for CYP with LLCs is essential to improve long-term outcomes in this population.

ORCID iDs

Seonhwa Lee https://orcid.org/0000-0002-9134-6319

Bohyun Park https://orcid.org/0000-0002-8538-9662

Ethical considerations

This study was approved by the Institutional Review Board (IRB) of the National Cancer Center (IRB No. NCC2023-0184).

Consent to participate

The requirement for informed consent to participate was waived by the Institutional Review Board because this study used anonymized national health insurance data.

Data Availability Statement

The datasets analysed during the current study are not publicly available due to legal and ethical restrictions, but may be accessed through the National Health Insurance Service (NHIS) of Korea upon reasonable request and approval.*