Introduction
Heart failure (HF) is a complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood. The cardinal manifestations of HF are dyspnea and fatigue, which may limit exercise tolerance, and fluid retention, which may lead to pulmonary and/or splanchnic congestion and/or peripheral edema. HF is one of the most important and severe end stages of many cardiovascular diseases [1, 2]. Epidemiological studies of HF have focused mainly on the prevalence, incidence, mortality, fatality, and distribution and temporal trends of these indicators among different populations. The purpose of this review is to highlight important epidemiological studies of HF in China.
Prevalence
The prevalence of HF refers to the rate of patients with HF in the specific population at the time of investigation. The prevalence of HF varies with time, population, area, and characteristics (Table 1).
Studies on the Prevalence of Heart Failure (HF) in China.
| Region | Time of study | Time of publication | Subjects | Prevalence |
|---|---|---|---|---|
| Liaoning [3] | 2008 | 2009 | n=33,027 Liaoning rural residents | Prevalence of HF, 1.61%. The prevalence of CHF in females (2.28%) was substantially higher than that in males (0.95%) |
| 10 provinces [4] | 2001 | 2003 | n=15,518 urban and rural residents in 10 provinces | Prevalence of HF, 0.9%. The prevalence of CHF in females (1.0%) was substantially higher than that in males (0.7%). The prevalence of CHF was higher in northern China than in southern China (1.4% and 0.5%, respectively) and was higher in urban areas than in rural areas (1.1% and 0.8%, respectively) |
| Hong Kong [5] | 1997 | 2000 | n=6.5 million Hong Kong residents | Prevalence of HF, 0.1% |
CHF, congestive heart failure.
The Chinese Multicenter Cooperation Study on Cardiovascular Health [4], the first national investigation of chronic HF prevalence in China, enrolled 15,518 adults aged 35–74 years from 10 provinces (five northern and five southern) using a four-stage random-sampling method. The prevalence rates of chronic HF were 0.9%, 0.7%, and 1.0% for the overall population, males, and females, respectively. When stratified by age, the prevalence rates of chronic HF were 0.4%, 1.0%, 1.3%, and 1.3% for groups aged 35–44, 45–54, 55–64, and 65–74 years, respectively, demonstrating the substantial increase in the prevalence of chronic HF with aging. The risk of chronic HF was higher in northern China (1.4%) than in southern China (0.5%), and was higher in urban areas (1.1%) than in rural areas (0.8%).
A large-scale study of regional chronic HF prevalence investigated the epidemiological characteristics and treatment of chronic HF in rural areas of Liaoning province [3]. By means of cluster random sampling, 33,027 rural residents aged 25–95 years were recruited. The study demonstrated that the rates of chronic HF prevalence were 1.61%, 0.95%, and 2.28% in the overall, male, and female populations, respectively. The prevalence rates of 0.12%, 0.79%, 1.98%, 3.71%, and 7.51% in groups aged 25–34, 35–44, 45–54, 55–64, and 65–74 years, respectively, demonstrated a substantial increase with age. The prevalence of chronic HF in females was substantially higher than that in males in every age group.
In 1997, Hung et al. [5] conducted a retrospective study of HF in Hong Kong by recruiting all patients admitted to the 11 hospitals of the Hospital Authority, Hong Kong, with a primary diagnosis of HF. A total of 6,203 patients were admitted from the emergency departments of these hospitals, among which 4,589 were new cases and 1,614 were old cases. To calculate the prevalence of HF that required hospital admission, the numbers of old and new cases were added; the corresponding prevalence rates for the 55–64-year and 65–74-year age groups were 1.3 and 4.4 per 1,000 men and 0.9 and 3.9 per 1,000 women, respectively. This study was based on hospitalization data rather than data from a population survey, which may partly explain the lower prevalence of HF in this study.
Incidence
The incidence of HF refers to the rate of new HF cases occurring during a certain time period (generally 1 year) in the population at risk.
In China, the only study [5] reporting the incidence of HF was the aforementioned study in Hong Kong. Among the 6,203 patients admitted from 11 hospitals, 4,589 were new cases. The incidence of HF was about 0.07% (number of new cases divided by the population of Hong Kong that year) and, when stratified by age groups, showed a rising trend with age. In the group aged more than 85 years, the incidence for women was 2% and that for men was 1.4%.
Etiology
HF is the severe end stage of a number of heart diseases, and its causes differ with economic performance/geographical area, living conditions, and living habits. The spectrum of causes of HF has changed with alterations in living conditions and habits caused by socioeconomic transformation (Table 2).
Studies of the Causes of Heart Failure (HF) in China.
| Region | Time of study | Time of publication | Subjects | Cause |
|---|---|---|---|---|
| Beijing [6] | 2010 | 2011 | n=6,949 congestive HF in-hospital patients | Coronary artery disease 45.0%, hypertension 38.7%, rheumatic valvular heart disease 27.5%, diabetes mellitus 18.3% |
| Liaoning [3] | 2008 | 2009 | n=532 HF patients | Coronary artery disease 68.36%, hypertension 13.37%, myocardiopathy 6.99%, rheumatic valvular heart disease 3.95% |
| Guangxi [7] | Jan. 1998 to Dec. 2002 | 2008 | n=1,296 HF inpatients | Coronary artery disease 30.71%, hypertension 17.56%, pulmonary heart disease 14.12%, rheumatic valvular heart disease 11.81%, chronic renal insufficiency 7.18%, dilated cardiomyopathy 6.48% |
| 17 provinces [8] | 2005 | 2005 | n=2,100 local physicians | Coronary artery disease 57.1%, hypertension 30.4%, rheumatic valvular heart disease 29.6% |
| 42 hospitals [9] | 1980; 1990; 2000 | 2002 | n=10,714 HF inpatients | In 1980, coronary artery disease 36.8%, rheumatic valvular heart disease 34.4%, hypertension 8.0% In 1990, rheumatic valvular heart disease 34.3%, coronary artery disease 33.8% In 2000, coronary artery disease 45.6%, rheumatic valvular heart disease 18.6% |
| Shanghai [10] | 1980; 1990; 2000 | 2002 | n=2,178 HF inpatients | In 1980, rheumatic valvular heart disease 46.8%, coronary artery disease 31.1%, hypertension 8.5%, dilated cardiomyopathy 6.0% In 1990, rheumatic valvular heart disease 24.2%, coronary artery disease 40.6%, hypertension 10.3%, dilated cardiomyopathy 6.9% In 2000, rheumatic valvular heart disease 8.9%, coronary artery disease 55.7%, hypertension 13.9%, dilated cardiomyopathy 7.5% |
| Hong Kong [11] | 1992 | 1995 | n=730 HF patients | Hypertension 37%, ischemic heart disease 31%, valvular heart disease 15%, cor pulmonale 27%, idiopathic dilated cardiomyopathy 4%, miscellaneous causes 10% |
In the 1980s, almost 50% of HF cases were attributable to rheumatic valvular heart disease, but the incidence of HF has declined significantly in the past three decades. Damage to the heart can be mitigated early because of improvements in living conditions and habits that have resulted from fast economic development and popularization of rheumatic valvular heart disease prevention and early detection and treatment. There has been a clear increase in the incidence of coronary heart disease (CAD) because of unhealthy lifestyles and the concomitant rise in risk factors for atherosclerosis. The CAD mortality rate, however, has gradually decreased because of improved management of acute CAD events. Therefore, CAD has become the main cause of HF in China.
A retrospective investigation of hospitalized patients with HF in some parts of China in 1980, 1990, and 2000 [9] analyzed the data of patients with primary diagnoses of chronic HF from 42 hospitals in urban China. This study demonstrated that the common causes of HF were CAD, rheumatic valvular heart disease, and hypertension. From 1980 to 2000, the rate of CAD rose from 36.8% to 45.6%, and the rate of hypertension rose from 8.0% to 12.9%. Over the same period, the rate of rheumatic valvular heart disease fell from 34.4% to 18.6%, and the proportion of all cardiac deaths caused by HF remained unchanged.
A study from a tertiary hospital in Beijing [6] identified 6,949 patients (4,344 males and 2,605 females) with a principal International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) discharge diagnosis of congestive HF. The reasons for hospitalization of patients with congestive HF were CAD (45.0%), hypertension (38.7%), valvular heart disease (27.5%), and diabetes mellitus (18.3%).
A pilot survey of the main causes of chronic HF in patients treated in primary hospitals in China was conducted by Cao et al. [8]. Local physicians from 2,066 local hospitals (at least one cardiologist, emergency department physician, or attending physician from each hospital) in 17 areas (11 provinces, three municipalities, and three autonomous regions) responded to questionnaires regarding hospitalized HF patients, and 2,100 valid responses were obtained. The research showed that the top three main causes of chronic HF were CAD (57.1%), hypertension (30.4%), and rheumatic heart disease (29.6%). In some places, chronic pulmonary heart disease was also a main cause of admission for chronic HF in primary hospitals.
The Shanghai Investigation Group of Heart Failure [10] analyzed evolving trends in the epidemiological factors and treatment of hospitalized patients with congestive HF in Shanghai during 1980, 1990, and 2000 using a retrospective method based on case records. A total of 2,178 patients were enrolled (mean age, 64.0 ± 16.0 years). The results showed that the cause of HF had shifted significantly from rheumatic valvular disease to CAD during the first two decades; the rate of HF due to rheumatic valvular disease decreased from 46.8% to 8.9%, and that of HF due to CAD rose from 31% to 55.7%.
An investigation of epidemiological characteristics and treatment of chronic HF in rural areas of Liaoning province [3] was conducted by cluster random sampling. A total of 33,027 rural residents aged 25–95 years from six counties of Liaoning province were enrolled: 532 were found to have HF. The study demonstrated that the causes of chronic HF were CAD (68.36%), hypertension (13.37%), myocardiopathy (6.99%), rheumatic valvular disease (3.95%), congenital heart disease (1.69%), and other cardiovascular disease (5.27%). Compared with previous studies, the proportion of HF cases caused by CAD increased significantly, ranking first; the prevalence of hypertension and myocardiopathy increased slightly, whereas the proportion of HF cases due to rheumatic valvular disease decreased substantially.
A retrospective study by Li [7] analyzed disease causes and prognosis of 1,296 hospitalized chronic HF patients in Guangxi province. The causes of chronic HF were CAD (30.71%), hypertensive heart disease (17.56%), pulmonary heart disease (14.12%), rheumatic valvular disease (11.81%), chronic renal insufficiency (7.18%), and dilated cardiomyopathy (6.48%).
Sanderson et al. [11] conducted the first epidemiological study of HF in Hong Kong. The prospective study of 730 consecutive HF patients (mean age, 73.5 ± 11.7 years) was performed to identify the main risk factors for or possible causes of HF. The main identifiable risk factors were hypertension (37%), CAD (31%), valvular heart disease (15%), cor pulmonale (27%), idiopathic dilated cardiomyopathy (4%), and miscellaneous factors (10%).
Medical Therapy
The common pathogenesis of HF is myocardial remodeling resulting in myocardial death (e.g., necrosis, apoptosis, and autophagy) and systemic reaction to overactivation of the renin-angiotensin-aldosterone system and the sympathetic nervous system. The foundation of effective HF prevention and treatment is to interfere with the disease process of this neurohormonal system [1] (Table 3).
Studies on Medical Therapy for Heart Failure (HF) in China.
| Region | Time of study | Time of publication | Subjects | Medical therapy |
|---|---|---|---|---|
| 31 provinces [12] | 2006 | 2012 | n=3,168 ACS inpatients | The usage rates of aspirin, β-blockers, ACEIs/ARBs, statins and clopidogrel/ticlopidine in HF patients without acute HF were 90.1%, 76.3%, 63.7%, 59.2%, and 30.5% respectively. The prescription rates of these drugs in acute HF patients were 92.7%, 77.6%, 67.6%, 70.4%, and 40.1% respectively |
| Hubei [13] | 2000–2010 | 2012 | n=16,681 HF inpatients | β-blockers 46.58%, ACEIs 51.60%, ARBs 18.68%, digoxin 46.24%, diuretics 69.13% |
| Liaoning [3] | 2008 | 2009 | n=532 HF patients | Digoxin 6.8%, furosemide 2.45%, hydrochlorothiazide 1.69%, spironolactone 0.38%, ACEIs 4.33%, β-blockers 3.77%, nitrate 3.77% |
| 17 provinces [14] | 2005 | 2006 | n=2,100 local physicians | Orally administered digitalis 60%, large-dose digitalis 10%, β-blockers 40%, ACEIs 80%, spironolactone 50% |
| 42 hospitals [9] | 1980; 1990; 2000 | 2002 | n=10,714 HF inpatients | In 1980, diuretics 63.7%, digoxin 51.7%, nitrate 44.7%, β-blockers 8.5%, ACEIs 14.0%, aldosterone receptor antagonists 10.0% In 1990, diuretics 70.2%, digoxin 45.5%, nitrate 36.0%, β-blockers 9.5%, ACEIs 26.4%, aldosterone receptor antagonists 8.4% In 2000, diuretics 48.6%, digoxin 40.3%, nitrate 53.0%, β-blockers 19.0%, ACEIs 40.4%, aldosterone receptor antagonists 20.0% |
| Shanghai [10] | 1980; 1990; 2000 | 2002 | n=2,178 HF inpatients | Diuretics 77.1%, nitrate 74.4%, digoxin 60.0% |
ARB, angiotensin-receptor blocker; ACEI, angiotensin-converting enzyme inhibitor; ACS, acute coronary syndrome.
The Bridging the Gap on CHD Secondary Prevention in China (BRIG) project [12] enrolled 65 hospitals from 31 provinces in mainland China and the Hong Kong Special Administrative Region using a multistage nonrandomized sampling approach. A questionnaire was completed according to the medical records of 3,168 patients with acute coronary syndrome. There were 706 patients (22.3%) with acute HF, and 262 (8.3%) HF patients did not have an acute episode during hospitalization. The prescription rates were determined for aspirin (90.1%/92.7%), β-blockers (76.3%/77.6%), angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin-receptor blockers (63.7%/67.6%), statins (59.2%/70.4%), and clopidogrel/ticlopidine (30.5%/40.1%) in HF patients without acute HF and acute HF patients, respectively.
The investigation of hospitalized patients with HF in some parts of China in 1980, 1990, and 2000 [9] demonstrated that medical treatment during hospitalization was mainly diuretic (55.4%), nitrate (43.2%), and digoxin (48.2%) therapy. The administration of digoxin decreased slightly (51.7% in the 1980s, 45.5% in the 1990s, and 40.3% in the first decade of this century, respectively). The use of β-blockers and ACEIs increased gradually, from 8.5% and 14.0%, respectively, in the 1980s to 19.0% and 40.4%, respectively, in the first decade of this century.
The Shanghai Investigation Group of Heart Failure [10] study showed that medical treatment has remained mostly conventional in the past decades, and determined the proportions of diuretics (77.1%), nitrate (74.4%), and digoxin (60.0%) administered. ACEI and β-blocker administration substantially increased, but the use of digoxin decreased.
The survey of local physicians by Cao et al. [14] showed that current chronic HF medications used in primary hospitals in China were not optimal. The usage rate of high-dose digitalis (≥0.25 mg/day) was 10%. The rates of β-blocker and ACEI administration were still low (40% and 80%, respectively), and the usage rates of target doses of β-blocker and ACEI were even lower (1% and 2%, respectively), and in some underdeveloped areas (e.g., Qinghai and Guizhou provinces) were zero. The usage rate of diuretics in symptomatic chronic HF patients was 90%.
An investigation of the epidemiological characteristics and treatment of chronic HF in some rural areas of Liaoning province [3] demonstrated that traditional Chinese medicine was widely used in this rural area and that the administration of recommended medicine was still very limited. The drugs used were digoxin (6.8%), furosemide (2.45%), hydrochlorothiazide (1.69%), spironolactone (0.38%), ACEIs (4.33%), β-blockers (3.77%), and nitrate (3.77%).
An investigation of the prevalence and related factors of medicinal therapy in patients with chronic systolic HF was done by Yu et al. [13]. Data on 16,681 patients hospitalized with chronic systolic HF were taken from 12 tertiary hospitals in eight cities of Hubei province in 2000 to 2010. Analysis determined the usage rates of β-blockers (46.58%), ACEIs (51.60%), angiotensin-receptor blockers (18.68%), digitalis (46.24%), and diuretics (69.13%). The use of angiotensin II–receptor blockers increased with age, and the distribution of digitalis, diuretics, β-blockers, and ACEIs showed an inverted-U shape. Sex differences were seen between different age groups.
Prognosis
The indicators of prognosis include mortality and rehospitalization rate. Mortality refers to the rate of death among HF patients, including in-hospital mortality and long-term mortality (1–5 years). The prognosis of HF is closely associated with the patient’s age and quality of life, the disease course, and the severity. A declining trend has been demonstrated for HF mortality with improving treatment over the past few decades (Table 4).
Studies on the Prognosis of Heart Failure (HF) in China.
| Region | Time of study | Time of publication | Subjects | Prognosis |
|---|---|---|---|---|
| 31 provinces [12] | 2006 | 2012 | n=3,168 ACS inpatients | The in-hospital mortality rate of HF patients and acute HF patients was 1.9% and 10.8%, respectively. The incidence of composite end point in HF patients and acute HF patients was 6.9% and 30.3%, respectively. The median length of hospital stay of HF patients and acute HF patients was 11.3 days and 13.2 days, respectively |
| Beijing [6] | 2010 | 2011 | n=6,949 congestive HF inpatients | The in-hospital mortality was 5.4%. Overall, as the age and the number of comorbidities increased, in-hospital mortality also increased for both men and women. The hazard of death increased with the number of comorbidities |
| 42 hospitals [9] | 1980; 1990; 2000 | 2002 | n=10,714 HF inpatients | The in-hospital mortality decreased gradually: 15.4% (1980), 12.3% (1990), and 6.2% (2000). The mean length of stay decreased yearly: 35.1 days (1980), 31.6 days (1990), and 21.8 days (2000) |
| Shanghai [10] | 1980; 1990; 2000 | 2002 | n=2,178 HF inpatients | The in-hospital mortality decreased gradually: 13.8% (1980), 11.5% (1990), and 6.0% (2000). The mean duration from diagnosis to death difference was not significant: 33.6 months (1980), 37.1 months (1990), and 40.5 months (2000) |
| Hong Kong [5] | 1997 | 2000 | n=6,203 HF inpatients | The 1-year mortality rate overall was 32%. The 1-year mortality rates of the male and female patients were similar and showed a rising trend with age |
ACS, acute coronary syndrome.
The BRIG project [12] demonstrated the in-hospital mortality rates of HF patients and acute HF patients were 1.9% and 10.8%, respectively. The incidence of composite end point (death, myocardial reinfarction /infarction, serious dysrhythmia, and stroke) in HF patients and acute HF patients was 6.9% and 30.3%, respectively. The median lengths of hospital stay were 11.3 days for HF patients and 13.2 days for acute HF patients.
A retrospective investigation of hospitalized patients with HF in some parts of China in 1980, 1990, and 2000 [9] found that the rates of correction of HF during hospitalization were 15.5% in 1980, 19.6% in 1990, and 22.2% in 2000. Mortality decreased significantly in those years, from 15.4% in 1980 to 12.3% in 1990 to 6.2% in 2000, but was still higher than that of all cardiac diseases during the same period. The mean length of stay decreased from 35.1 days in 1980 to 31.6 days in 1990 to 21.8 days in 2000.
In a Beijing study [6] of 6,949 congestive HF patients, in-hospital mortality was 5.4%. Overall, in-hospital mortality increased with age and the number of comorbidities in both men and women. The hazard of death increased with the number of comorbidities.
The Shanghai Investigation Group of Heart Failure [10] retrospective study of 2,178 patients revealed that in-hospital mortality declined from 13.8% in 1980 to 11.5% in 1990 to 6% in 2000. The mean duration from diagnosis to death was 33.6 months in 1980, 37.1 months in 1990, and 40.5 months in 2000. The average number of emergency visits and hospital admissions within 1 year before the current hospitalization numbered 3.1 in 1980, 2.8 in 1990, and 2.0 in 2000. The major causes of death were progressive HF (53.2%) and complications (38.2%).
A retrospective study [5] of HF in Hong Kong began in 1997 and analyzed survival status up to 1 year. The 1-year mortality rate overall was 32%; the 1-year mortality rates of male and female patients were similar and showed a rising trend with age. Old cases of HF had a 5–10% higher mortality rate than new cases across all age groups.
Conclusion and Take-Home Message
HF is becoming more prevalent in China, especially in older people. This results in increasing medical costs and increasing rates of disability and mortality. At present, evidence from epidemiological research on HF in China is not yet sufficient to guide the development of prevention strategies. Therefore, large-scale epidemiological studies should be conducted to assess the current situation and overall trends, and to provide a scientific basis for effective prevention strategies.