Long-term health-related burden of adult congenital heart diseases in Hong Kong

Abstract

Aims: This study aimed to examine the long-term clinical and economic burden of adults with congenital heart disease (ACHD) in Hong Kong.

Methods: It retrospectively analyzed 336 consecutive ACHD patients who attended the Adult Congenital Heart Clinic between January 1, 2009 and December 31, 2014. Direct medical costs and clinical outcomes over the 5 years were calculated and documented. The economic evaluation was from the hospital’s perspective.

Results: The median age of ACHD patients was 47 (31–62) years old, with female predominance (61.5%). Ventricular and atrial septal defects accounted for 70% and severe ACHD for 10% of the study cohort. The prevalence of arrhythmia and heart failure increased with the complexity of CHD. The total mean annual cost for managing each ACHD patient was USD 2,913. The annual cost of management of simple ACHD was USD 2,638 vs complex ACHD (USD 6,425) (p = 0.013).

Conclusions: This study demonstrated severe ACHD patients accounted for higher cardiovascular morbidities in arrhythmias and heart failure with a higher cost of management.

Keywords:

• Congenital heart disease
• healthcare burden
• long-term outcomes

JEL classification codes:

• I10
• I19

Background

Congenital heart disease (CHD) is the most common cause of congenital anomalies, representing a global health issue. Birth prevalence of CHD is approximately eight per 1,000 live births¹. Advancements in echocardiography, pediatric intensive care, and particularly cardiac surgery lead to a dramatic increase in the survival rate of CHD patients. Five decades ago, patients with moderate-to-severe CHD hardly survived, but now over 90% of them survive until adulthood². In the US, it has been suggested that over 1 million adults have CHD³. A recent report from Canada also demonstrated that adults accounted for 66% of the entire CHD population, implying that CHD is no longer a pediatric specialty⁴. Such an emerging population of adults with CHD (ACHD) has become a major challenge to medical systems worldwide^4–6. Until now, epidemiological data of ACHD patients has been limited. Therefore, it is essential to study the ACHD population so as to guide healthcare providers to tailor management for ACHD patients. The most widely adopted classification of CHD based on the severity of disease and extent of specialized care were outlined in the 32rd Bethesda Conference⁷. Congenital heart disease can be divided into three groups, namely simple CHD, CHD of moderate complexity, and CHD of severely complexity. Both moderate and severely complex patients require a life-long follow-up from centers specialized in congenital heart care, while simple patients may require care from the general medical community.

Several large registries have been established to collect epidemiological data for ACHD patients^2,5,8. The CONCOR registry in the Netherlands had recruited more than 14,000 ACHD patients from 102 hospitals. In this registry, a nearly equal number of females and males were recruited (49.5% vs 50.5%). Congenital heart defects were classified into simple, moderate, and severe cardiac defects, which constituted 56%, 34%, and 10%, respectively⁹. Another well-known registry is the Quebec study from Canada, which is a population study of 28 years based on a government database⁴; 39,051 adults were included in the study, with a median age of 40 years and female predominance (56%). Ten per cent were severe ACHD patients².

Because of late complications and lifelong follow-up, the growing ACHD population may pose a significant financial burden on the healthcare system. Several studies were done to focus on the cost estimation for hospitalization of ACHD patients^10–13. A nationwide study in the US found that total cost for hospitalization of ACHD patients had increased dramatically from $691 million to $3.16 billion in 8 years¹¹. Furthermore, there are a growing number of elderly ACHD patients with higher utilization of healthcare resources¹³. Nevertheless, overseas data on cost estimation may not reflect the cost in local practice. Direct medical costs for managing ACHD have never been studied in Hong Kong. Therefore, the current project aimed to evaluate the impact of CHD in respect to clinical and economic outcomes.

Methods

Study design

This is a retrospective cohort study conducted in the Prince of Wales Hospital, a regional cardiac hospital in Hong Kong, based on the established ACHD registry. Patients with cardiac follow-up during November 1, 2013 to October 31, 2014 were included for analysis. The current study was approved by the research ethics committee of the Prince of Wales Hospital.

Subject recruitment

Subjects aged at least 18 years old with a diagnosis of CHD according to International Classification of Diseases, 10th Revision (ICD-10), coding from Q20.0 to Q20.9 were included in this study. However, those who were born with cardiomyopathy, Marfan syndrome, congenital arrhythmia, isolated bicuspid aortic valve, mitral valve prolapse, atrial septal defect, or patent ductus undergoing spontaneous closure were excluded, since these conditions do not fall into the definition of CHD according to Mitchell et al.¹⁴.

Outcome measurements and data extraction

Demographic data, main CHD diagnosis, and the severity of CHD were collected from the ACHD registry in the Prince of Wales Hospital. The severity of CHD was classified into simple, moderate, and severe according to the 32nd Bethesda Conference⁷. The clinical, economic, and humanistic outcomes of the patients with different severity of CHD would then be compared. Only living patients with cardiac follow-up in the past 1 year would be included for the clinical and economic outcomes analysis.

Clinical outcomes

Diagnoses of late complications of CHD, including arrhythmia (ICD-10 I47–I49), heart failure (ICD-10 I50), infective endocarditis (ICD-10 I33) and pulmonary hypertension (ICD-10: I27.0–I27.2) were obtained via the Clinical Management System of Hospital Authority.

Economic outcomes

Direct medical cost from November 1, 2009 to October 31, 2014 was estimated based on the following parameters: duration of hospitalization in days, number of emergency room admissions, number of general outpatient clinic visits and specialty outpatient clinic visits, diagnostic procedures, laboratory test performed, cardiac operation and catheterization, chronic cardiac medication, and medication used during hospitalization. The cost of the medications was obtained from the Prince of Wales Hospital, while other costs were calculated based on the Hong Kong Government Gazette 2003.

Statistical analysis

Descriptive statistics were used to present demographics and outcome data. Categorical data were presented as percentages, while continuous data were presented as either mean with standard deviation or median with interquartile ranges subjected to normality of the data. The Chi-square test was used to compare categorical data, while one-way analysis of variance (ANOVA) was used to compare continuous data. Post-hoc analysis was then performed to identify the difference between groups if ANOVA was statistically significant. A p-value of < 0.05 was considered as statistically significant. All data were analyzed with the Statistics Package for Social Sciences (SPSS) version 20.0.

Results

Demographics

A total of 433 patients were identified, 56 patients died and 41 patients were lost to follow up for more than 1 year. The remaining 336 patients were eligible for the clinical and economic outcomes evaluation. 228 of them were included in the humanistic outcome analysis. The demographic data of all identified patients are summarized in Table 1. Ventricular Septal Defect (VSD) (35.6%), Atrial Septal Defect (ASD) (34.4%), and Patent Ductus Arteriosus (PDA) (9.5%) were the main three diagnoses (Table 2). Patients with VSD and Tetralogy of Fallot (ToF) had a median age less than 40 years, while patients with ASD, PDA, and Patent Foramen Ovale (PFO) had a median age > 40 years.

Table 1. Demographic data of all identified congenital heart disease patients.

	Living patients	Death cases	Total
n	377 (85.7%)	56 (12.9%)	433 (100.0%)
Median age	43 (30–58)	66.5 (52–77.5)	47 (31–62)
Female	232 (61.5%)	33 (58.9%)	265 (61.2%)
Ethnicity
Chinese	364 (96.6%)	56 (100.0%)	420 (97.0%)
English	2 (0.5%)	0 (0%)	2 (0.5%)
Philippine	1 (0.3%)	0 (0%)	1 (0.2%)
Others	10 (2.7%)	0 (0%)	10 (2.3%)
Disease complexity
Simple	208 (55.2%)	22 (39.3%)	230 (53.1%)
Moderate	130 (34.5%)	16 (28.6%)	146 (33.7%)
Complex	39 (10.3%)	18 (32.1%)	57 (13.2%)

Table 2. Top five heart defects of congenital heart disease.

Heart defect	n	Median age (IQR)	Female proportion
Ventricular Septal Defect	154 (35.6%)	39.5 (28.0–56.0)	53.6%
Atrial Septal Defect	149 (34.4%)	54.0 (36.0–63.0)	65.1%
Patent Ductus Arteriosus	41 (9.5%)	62.0 (50.0–69.0)	70.4%
Tetralogy of Fallot	34 (7.9%)	24.5 (22.0–35.0)	40.6%
Patent Foramen Ovale	23 (5.3%)	50.0 (25.0–75.0)	73.7%

Table 3. Summary of clinical and economic outcomes.

	All patients	Simple	Moderate	Severe	p-value
Clinical outcomes
n	336	176	123	37
Arrhythmia	65 (19.3%)	31 (17.6%)	20 (16.2%)	14 (37.8%)	0.010
Heart Failure	36 (10.7%)	14 (8.0%)	13 (10.6%)	9 (24.3%)	0.014
Pulmonary Hypertension	23 (6.8%)	0 (0.0%)	0 (0.0%)	23 (62.2%)	N/A
Infective Endocarditis	12 (3.6%)	5 (2.8%)	6 (4.9%)	1 (2.7%)	0.618
Economic outcomes
n	336	176	123	37
Annual cost	US$2,912.5	US$ 2,637.6	US$ 2,249.6	US$ 6,425	*

* p-value is 0.026 for moderate vs severe and 0.013 for simple vs severe.

Outcome measurements

Clinical outcomes

Arrhythmia was the most common complication, with an occurrence of 19.3%. The incidence rates of heart failure, pulmonary hypertension, and infective endocarditis were 10.7%, 6.8%, and 3.6%, respectively. Atrial fibrillation was the most common arrhythmia in ACHD patients (12.5%), followed by atrial flutter (2.7%) and heart block (1.5%) (Table 3). Of the 336 ACHD patients, 217 subjects (65%) had undergone CHD procedures in their lifetime. The median age of a patient receiving their first surgery was 35 years (IQR = 12–55). One hundred and eighty-one subjects (86.2%) received only one operation in their lifetime and the average number of procedures done was 1.2 per patient. The most common type of surgery was atrial (100/168, 59.5%) or ventricular septal defects closure (34/168, 20.2%), followed by ToF repair (25, 9.8%) and heart valve repair (24, 9.4%).

Economic outcomes

The direct medical cost for 336 CHD patients was found to be US$4.9 million, accounting for 0.8% of the public health expenditure. Hospitalization cost constituted the largest proportion (US$1.65 million, 33%) followed by medication (US$0.85 million, 17%) and diagnostic procedures (US$0.74 million, 15%). The mean annual cost for each CHD patient was US$2,912.5 ± 4,552.6. The annual cost was highest in the severe CHD group and lowest in the moderate CHD group. The cost for each severe CHD patient was 2.86-times that of the moderate group (US$6,425 vs US$2,249.6, p = 0.026) and 2.45-times that of the simple group (US$6,425 vs US$2,637.6, p = 0.013) (Table 3).

Discussion

With the aging population, the healthcare budget on public health expenditure is under pressure. According to the Hong Kong Domestic Health Account 2012, the total health expenditure was approximately US$13.1 billion (US$1,848.8 per capita), of which 49% (US$6.4 billion) was public health expenditure¹⁵. This study gives an estimation of annual direct medical cost in the management of ACHD, which may give some implications to the largest public healthcare provider—Hospital Authority—to distribute resources with efficient containment of healthcare cost. The mean annual cost in managing ACHD per capita was US$2,912.6, which was 4-times less than the first-year costs for management of stable angina in Hong Kong (US$2,912.6 vs US$11,476.7)¹⁶. The current study demonstrated the total annual cost for managing all CHD patients was estimated to be US $4.9 million accounting for 0.8% of the public health expenditure. Our findings indicate that the direct medical cost varied considerably with defect severity and age. Direct medical cost for severe cardiac defects was 2.85-times higher than that of a simple cardiac defect. Previous literature also found that the rate of hospitalization was higher in patients with severe cardiac lesions when compared to other cardiac lesions¹⁷. Adults with severe cardiac lesions are high users of healthcare utilization, as they require more cardiologist outpatient care, emergency room visits, and critical care services¹⁷. With the aging population of ACHD patients, more patients live long to acquire general medical comorbidities, so there is a growing trend for increasing the utilization of health resource for non-CHD diseases.

The majority of the ACHD patients recruited in this registry were female (61.5%). A Canadian population-based study, the Quebec study, also demonstrated that women are more prevalent (57%) than men for ACHD². Potential causes to explain the predominance of women in ACHD patients included different sex pattern of CHD at birth, milder lesions in females, and differences in mortality related to CHD clinical outcomes². Compared to the Dutch study (CONCOR registry), live ACHD patients in our registry were older (median age = 43 years vs 33.1 years). The median age at death in our patients was also higher than that of the CONCOR registry (66.5 vs 48.8 years)⁵. The advanced age of our patients may increase the risk of acquired comorbidities in conjunction with the underlying CHD problems. About half of the ACHD patients had simple cardiac lesion, while only one-tenth (10.3%) of the total had severe cardiac lesions. A similar proportion of severe cardiac lesions (10.1%) was also reported in the Quebec study⁴. Ventricular septal defect (35.6%) and ASD (34.4%) are the most prevalent types of CHD in ACHD patients, followed by PDA (9.5%), ToF (7.9%) and PFO (5.3%). The Quebec study showed that congenital AS (16%) was the most common type of CHD, followed by ASD (13.9%) and VSD (10.1%)⁴. The low incidence of AS in our patients may be explained by lower incidence of congenital aortic stenosis in Chinese pediatric patients in the previous report¹⁸.

Due to the nature of the retrospective design, the study has inherent bias and it highly relies on the accuracy of recorded data. If the clinical data are not recorded, missing data can result, and this would affect the conclusions drawn. Since this is a single center study with a relatively small sample size compared to the CONCOR or Quebec national registry, it may not be able to examine the outcomes of rare defects and the true prevalence of CHD in Hong Kong. In our registry more than 60% of patients recruited were female, which may be due to selection bias and the small sample size.

Because of the heterogeneity of the disease, CHD defects were grouped into simple, moderate, and complex defects based on ICD-10 classifications, which were prone to misclassifications. In addition, we only evaluated the direct medical cost from the hospital perspective from the public sector, we did not study from the patient’s perspective by evaluating the cost associated with private general practitioner visits, private cardiologist visits, diagnostic and intervention procedures, and hospitalization cost from private hospitals.

Conclusion

This is the first report on an epidemiogological study of ACHD patients in Hong Kong. Our study demonstrated severe ACHD patients accounted for higher cardiovascular morbidities in arrhythmias and heart failure with higher cost of management.

Transparency

Declaration of funding

This paper was not funded.

Declaration of financial/other interests

All authors declare that there was no conflict of interest during the study and the preparation of the manuscript. JME peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Details of ethical approval

The study was approved by the Ethics Committee, CUHK-New Territories East Cluster, Hospital Authority, Hong Kong.

Acknowledgements

None reported.

Data availability statement

The datasets during and/or analyzed during the current study are available from the corresponding author on reasonable request.