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Prevalence of cardiovascular diseases in elderly Chinese people in Taiwan
International Journal of Cardiology 67 (1998) 177–181
Prevalence of cardiovascular diseases in elderly Chinese people in Taiwan Chiau-Suong Liau*, Yuen-Zu Tseng, Ti-Kai Lee National Taiwan University Hospital, No. 7, Chung-shan S. Road, Taipei, Taiwan, Republic of China Received 24 June 1998; accepted 14 September 1998
Abstract In order to study the health status and prevalence of diseases in elderly Chinese people in Taiwan, a hospital-based, physicianconducted epidemiological survey was undertaken. Study subjects were people aged $65 years who were randomly selected from four regions of Taiwan. A total of 2600 subjects were studied. Most of the study subjects visited the hospitals for detailed history taking, physical examination and laboratory tests, including urinalysis, blood chemistry, electrocardiography, and chest and lumbar spine radiography. The cardiovascular data of 2518 subjects (males 1283) comprised this report. The prevalence of hypertension in the aged Chinese in Taiwan was high in both males and females (males 33.2%, females 40.9%, combined 37%). Coronary artery disease was also common (11.4%), but the prevalence was relatively low compared with Western people. Other cardiovascular diseases such as aortic aneurysm and valvular heart disease were rare. About 70% of the electrocardiograms were found abnormal. This well-organized, large-scale epidemiological survey not only presents useful information for local medical care for the elderly but also provides important data for comparison between different people in the world. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Aged people; Cardiovascular disease; Prevalence; Hypertension; Coronary artery disease
1. Introduction The information on the health status and the prevalence of diseases in a population is crucially important to both practising physicians and the policy-making administrators. This kind of knowledge is essentially incomplete in Taiwan, the Republic of China, especially for the aged subgroup. The population in Taiwan is over 21 millions and the population aged $65 years has exceeded 7.0% since 1994 [1]. Therefore, it is timely to look at the health and the disease profile of the elderly people in this country. For this purpose, a survey was launched under the sponsorship of the National Health Administration of the Republic of China. This survey *Corresponding author.
was conducted by the Geriatric Study Group of the Gerontological Society, the Republic of China.
2. Subjects and methods
2.1. Study population The selection of study subjects and the methods of study were reported previously [2]. In brief, the survey was conducted from April 1989 through June 1991 to evaluate the health status of persons aged $65 years of age. Samples were drawn from four areas of Taiwan: Taipei, Taichung, Kaoshiung and Hualien, representing the northern, central, southern and eastern parts of the country. From each ‘Li’ (the smallest administration unit) in the four areas a
0167-5273 / 98 / $ – see front matter 1998 Elsevier Science Ireland Ltd. All rights reserved. PII: S0167-5273( 98 )00282-4
178
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181
random sample of two subjects was chosen: one man and one woman aged $65 years whose names were the first to appear in the selected census registration books.
between age and sex groups. A P value of ,0.05 was regarded as statistically significant.
3. Results
2.2. Methods
3.1. Study subjects
The studies were executed by local medical centers, including the National Taiwan University Hospital, the Taichung Veterans General Hospital, the Kaoshiung Medical College Hospital and the Tz’uchi Buddhist General Hospital. The study subjects were organised to visit one of the participating hospitals in the morning for history taking, physical examination and laboratory examinations. A questionnaire on medical history, including history of hypertension, heart diseases and operation on cardiovascular system was also completed. Laboratory tests included blood chemistry, urinalysis, electrocardiography and chest and lumbar spine Xray. All the electrocardiograms were interpreted by two qualified cardiologists and all the chest X-ray films were judged by one chest physician. The information was pooled at the steering center located in the National Taiwan University Hospital. In cases where the candidates could not attend the hospital, home visits were undertaken by qualified doctors; history taking and physical examination only were performed. In this communication only the cardiovascular data are presented. The criteria for the diagnosis of hypertension followed that of World Health Organization, i.e., systolic blood pressure $160 mm Hg and / or diastolic blood pressure $95 mm Hg [3]. Those with a definite history of hypertension who were receiving antihypertensive medication at the time of survey were also diagnosed as having hypertension disregarding the blood pressure readings at the time of examination. The diagnosis of coronary artery disease was made if one or more of the following conditions were present: (1) previous definite diagnosis of coronary artery disease, such as history of myocardial infarction, presence of significant coronary lesions by coronary angiography; (2) symptoms of typical angina pectoris; (3) unequivocal electrocardiographic findings of myocardial infarction and / or ischemia. The x 2 test was used for the comparison of data
A total of 2600 subjects (males 1322, females 1278) were included in the study. Among them, 2518 (1283 males and 1235 females) with complete cardiovascular data are included in the present report. The age distribution for both males and females is depicted in Table 1. The age distribution of the males and females was significantly different (P,0.005) with more male subjects distributed to the more elderly group ($75 years of age).
3.2. Hypertension Hypertension was diagnosed in 931 subjects, a prevalence rate of 37.0%. Of those, 686 were diagnosed by elevated blood pressure at physical examination. In the remaining 245 the blood pressure was not elevated at examination but hypertension was diagnosed from the history. Female subjects showed a significantly higher prevalence of hypertension than the males (40.9% vs. 33.2%, P,0.001). In the age group 65–74 years, the rate of hypertension was 40.7% for females and 32.1% for males (P,0.001). The sex difference was not evident for subjects aged 75 years or older (Table 2). Isolated systolic hypertension was the most common form of hypertension (365 subjects, or 53.2% of all hypertensive subjects who had elevated blood pressure at examination), followed by combined systolic and diastolic hypertension (232 cases, 33.8%) and isolated diastolic hypertension (89 cases, 13%). The isolated systolic hypertension was found Table 1 Age–gender distribution of the study subjects Age group 65–74 years Male Female Total
Total $75 years
966 990
317 245
1283 1235
1956
562
2518
* P,0.005 for age distribution between males and females.
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181
179
Table 2 Prevalence of hypertension Diagnosed by physical examination 65–74 years
Diagnosed by history $75 years
65–74 years
$75 years
Male Systolic Systolic1diastolic Diastolic
219 (94) (81) (44)
89 (55) (28) (6)
91
27
Female Systolic Systolic1diastolic Diastolic
297 (159) (101) (37)
81 (57) (22) (2)
106
21
516
170
197
48
Total
to be more prevalent in female subjects (17.5% vs. 11.6%, P,0.001) and also in the subjects aged $75 years than the subjects aged 65–74 years in both sexes (for males, 17.4% vs. 9.7%, P,0.001; for females, 23.3% vs. 12.9%, P,0.02). Antihypertensive therapy was taken by 607 subjects (males, 72.5%; females, 59%; combined, 65.2%), but only 34.3% of the treated subjects had their blood pressure controlled to normal levels.
3.3. Coronary artery disease Coronary artery disease was diagnosed by history and electrocardiograms. One hundred and thirty subjects (male 73, female 57) were diagnosed by history to have coronary artery disease, including 40 with histories of myocardial infarction and 90 with presence of typical angina pectoris. Diagnosis of coronary artery disease was made in another 156 subjects exclusively by electrocardiograms, including changes of myocardial infarction in 147 (male 77, female 70) and of myocardial ischemia in 55 (male 33, female 22). Thus, 286 subjects in total (males 160, females 126) were diagnosed as having coronary artery disease, giving a prevalence rate of 11.4% in our study population. Males and females showed no difference in the prevalence of coronary artery disease (male 12.5%, female 10.2%, P50.07).
3.4. Electrocardiographic findings Electrocardiograms were interpreted as normal in 725 subjects (28.8%). Sinus bradycardia was a
common electrocardiographic finding in our study population (14.9%). Left ventricular hypertrophy was also common (13.3%). Other frequent electrocardiographic changes included myocardial infarction, myocardial ischemia, complete right bundle branch block and various cardiac arrhythmias (Table 3).
3.5. Other cardiovascular diseases There were four subjects who had received permanent pacemaker implantation. Two cases had had operations on abdominal aortic aneurysm. Mitral stenosis was detected in eight subjects and ventricular septal defect in one by physical examination. Congestive heart failure was diagnosed in 83 cases by history taking and physical examination (males 33, females 50; 3.3% of the whole group). Table 3 Electrocardiographic findings
Normal Sinus bradycardia LVH Myocardial infarction Complete RBBB AF /Af Myocardial ischemia LA enlargement Complete LBBB RVH Other arrhythmias (PAC, PVC)
No. of cases
Percentage
725 374 334 147 97 61 55 26 15 7 150
28.8 14.9 13.3 5.8 3.9 2.4 2.2 1.0 0.6 0.3 6.0
Abbreviations: AF, atrial flutter; Af, atrial fibrillation; LA, left atrial; LBBB, left bundle branch block; LVH, left ventricular hypertrophy; PAC, premature atrial contraction; PVC, premature ventricular contraction; RBBB, right bundle branch block; RVH, right ventricular hypertrophy.
180
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181
4. Discussion Cardiovascular disease is one of the leading causes of mortality and morbidity in the modern era, especially for aged people [4–6]. Biostatistic data about the leading causes of death in Taiwan indicated that cardiac diseases ranked in fourth position in past decades [1]. Studies on the prevalence of cardiovascular diseases in Chinese people in Taiwan were sporadic and incomplete [7–9]. The present survey is distinctive in that it was hospital-based and conducted by physicians. Most of the examinees underwent complete history taking, physical examination and extensive laboratory tests. This well-designed, comprehensive large scale survey was expected to give useful information about the health status of the aged population living in this Island. As demonstrated in this study, the prevalence of hypertension in Chinese elderly people was high (37%) which is comparable to that reported for other people [10,11]. Ostfeld reported a prevalence rate of 50% for hypertension in one elderly population [12]. We found that female subjects had a higher prevalence of hypertension than males. This finding was consistent with previous reports [10,11]. It is widely appreciated that isolated systolic hypertension is the most common form of hypertension found in aged subjects [13,14]. Our data support this observation. The high systolic blood pressure is attributed to decreased arterial compliance —a consequence of aging process [14]. Among the hypertensives, antihypertensive therapy was taken by 65.2% subjects, indicating the wide acceptance of antihypertensive therapy by the elderly hypertensive population in Taiwan. But, control of blood pressure to normal level was achieved in only 34.3% of the treated individuals. The reason why more males took antihypertensive regimens was not clear. It was speculated that this might be due to males having more insurance coverage, such as government employees’ and laborers’ insurance. Coronary heart disease is the most important cause of death in the industrialized Western countries, although the incidence is decreasing in certain areas [15–19]. Yet, some countries reported a trend of increasing incidence of coronary artery disease, among them are Soviet Union [20], People’s Republic of China [21] and Taiwan [22]. In our survey, coronary heart disease was detected in only 11.4% of
the elderly Chinese, much lower than that of the US and some European countries. This low prevalence may be explained by the hereditary differences and by the insensitivity of the detection methods we used. Electrocardiograms were interpreted as being normal in 28.8% of our study subjects. This rate was lower than that reported by Campbell et al. [23]. Seventy percent of the electrocardiograms showed various changes. Some of these changes may be related to underlying abnormalities such as hypertension and coronary artery disease while others may be associated with the natural aging process or due to drug effects. As an example, the high prevalence of sinus bradycardia in our population might be partially attributed to the effect of some cardiovascular medicines, such as beta blockers and calcium channel antagonists. In conclusion, from this well organized epidemiologic study, we found that there is a high prevalence of hypertension in elderly Chinese people in Taiwan. Coronary artery disease was also common but the prevalence rate was much lower than that of the Western countries. Other cardiovascular diseases such as aortic aneurysm and valvular heart disease were quite rare in the elderly people. This information is not only useful for medical care of the elderly but may also provide knowledge for comparing cardiovascular diseases between different regions and different people in the world.
Acknowledgements This work was supported by a grant (DOH 80-25) from the Department of Health, Executive Yuan, Republic of China.
References [1] National health Administration, Executive Yuan, Republic of China: Health Statistics: I. Vital Statistics. National health Administration, 1971–1996. [2] Lee TK, Huang ZS, Ng SK, et al. Impact of alcohol consumption and cigarette smoking on stroke among the elderly in Taiwan. Stroke 1995;26:790–4. [3] Hypertension and Coronary Heart Disease: Classification and Criteria for Epidemiological Studies. First Report of the Expert Committee on Cardiovascular Diseases and Hypertension. Technical Report Series, No. 168. Geneva, World Health Organization, 1959. [4] Kohn RR. Human aging and disease. J Chronic Dis 1963;16:5–21.
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181 [5] Uemura K, Pisa Z. Recent trends in cardiovascular disease mortality in 27 industrialized countries. Wld Hlth Statist Quart 1985;38:142– 62. [6] Luepker RV. Epidemiology of atherosclerotic diseases in population groups. In: Pearson TA, Criqui MH, Oberman A, Winston M, editors. Primer in preventive cardiology. Am Heart Assoc, 1994: 1–10. [7] Tsai HC, Yen TS, Wang LT, Cheng JT, Tseng WP, Chen CM. An epidemiologic study of the cardiovascular diseases among the inhabitants of a fishing village in Taiwan. Report I. Blood pressure and hypertension. J Formosan Med Assoc 1966;66:249–58. [8] Tsai HC, Tseng WP, Yen TS, et al. Coronary heart disease and hypertension in Taiwan aborigines. Am J Epidemiol 1967;86:253– 63. [9] Tseng WP. Blood pressure and hypertension in an agricultural and a fishing population in Taiwan. Am J Epidemiol 1967;86:513–25. [10] National Center for Health Statistics: Hypertension and Hypertensive Heart Disease in Adults. Vital and Health Statistics, PHS Publ. No. 1000. Series 11, No. 13, 1966. Public Health Service, Washington, DC, US Government Printing Office. [11] National Center for Health Statistics, Roland M, Roberts J: Blood pressure levels and hypertension in persons ages 6–74: United States, 1976–1980. Advance data from vital and health statistics, No 84, DHHS Publ No (PHS) 82-1250. Hyattsville, MD, Public Health Service, October 8, 1982. [12] Ostfeld AM. Elderly hypertensive patients: epidemiologic review. NY State J Med 1978;78:1125–9.
181
[13] Kannel WB. Systolic blood pressure, arterial rigidity, and risk of stroke. J Am Med Assoc 1981;245:1225–9. [14] Rowe JW. Systolic hypertension in the elderly. New Engl J Med 1983;309:1264–70. [15] Kitchin AH, Lowther CP, Milne JS. Prevalence of clinical and electrocardiographic evidence of ischaemic heart disease in the older population. Br Heart J 1973;35:946–53. [16] National Heart, Lung, and Blood Institute: Morbidity from coronary heart disease in the United States. NHLBI data Fact Sheet, June 1990. [17] Tuomilehto J, Puska P, Korhonen H, et al. Trends and determinants of ischaemic heart disease mortality in Finland: with special reference to a possible levelling off in the early 1980s. Int J Epidemiol 1989;18:S109–17. [18] Beaglehole R, Dobson A, Hobbs MST, Jackson R, Martin CA. CHD in Australia and New Zealand. Int J Epidemiol 1989;18:S145–8. [19] Hatano S. Changing CHD mortality and its causes in Japan during 1955–1985. Int J Epidemiol 1989;18:S149–58. [20] Deev AD, Oganov RG. Trends and determinants of cardiovascular mortality in the Soviet Union. Int J Epidemiol 1989;18:S137–44. [21] Tao S, Huang Z, Wu X, et al. CHD and its risk factors in the People’s Republic of China. Int J Epidemiol 1989;18:S159–63. [22] Liau CS, Hahn LC, Tjung JJ, et al. The clinical characteristics of acute myocardial infarction in aged patients. J Formosan Med Assoc 1991;90:122–6. [23] Campbell A, Caird FI, Jackson FM. Prevalence of abnormalities of electrocardiogram in old people. Br Heart J 1974;36:1005–11.
Prevalence of cardiovascular diseases in elderly Chinese people in Taiwan Chiau-Suong Liau*, Yuen-Zu Tseng, Ti-Kai Lee National Taiwan University Hospital, No. 7, Chung-shan S. Road, Taipei, Taiwan, Republic of China Received 24 June 1998; accepted 14 September 1998
Abstract In order to study the health status and prevalence of diseases in elderly Chinese people in Taiwan, a hospital-based, physicianconducted epidemiological survey was undertaken. Study subjects were people aged $65 years who were randomly selected from four regions of Taiwan. A total of 2600 subjects were studied. Most of the study subjects visited the hospitals for detailed history taking, physical examination and laboratory tests, including urinalysis, blood chemistry, electrocardiography, and chest and lumbar spine radiography. The cardiovascular data of 2518 subjects (males 1283) comprised this report. The prevalence of hypertension in the aged Chinese in Taiwan was high in both males and females (males 33.2%, females 40.9%, combined 37%). Coronary artery disease was also common (11.4%), but the prevalence was relatively low compared with Western people. Other cardiovascular diseases such as aortic aneurysm and valvular heart disease were rare. About 70% of the electrocardiograms were found abnormal. This well-organized, large-scale epidemiological survey not only presents useful information for local medical care for the elderly but also provides important data for comparison between different people in the world. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Aged people; Cardiovascular disease; Prevalence; Hypertension; Coronary artery disease
1. Introduction The information on the health status and the prevalence of diseases in a population is crucially important to both practising physicians and the policy-making administrators. This kind of knowledge is essentially incomplete in Taiwan, the Republic of China, especially for the aged subgroup. The population in Taiwan is over 21 millions and the population aged $65 years has exceeded 7.0% since 1994 [1]. Therefore, it is timely to look at the health and the disease profile of the elderly people in this country. For this purpose, a survey was launched under the sponsorship of the National Health Administration of the Republic of China. This survey *Corresponding author.
was conducted by the Geriatric Study Group of the Gerontological Society, the Republic of China.
2. Subjects and methods
2.1. Study population The selection of study subjects and the methods of study were reported previously [2]. In brief, the survey was conducted from April 1989 through June 1991 to evaluate the health status of persons aged $65 years of age. Samples were drawn from four areas of Taiwan: Taipei, Taichung, Kaoshiung and Hualien, representing the northern, central, southern and eastern parts of the country. From each ‘Li’ (the smallest administration unit) in the four areas a
0167-5273 / 98 / $ – see front matter 1998 Elsevier Science Ireland Ltd. All rights reserved. PII: S0167-5273( 98 )00282-4
178
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181
random sample of two subjects was chosen: one man and one woman aged $65 years whose names were the first to appear in the selected census registration books.
between age and sex groups. A P value of ,0.05 was regarded as statistically significant.
3. Results
2.2. Methods
3.1. Study subjects
The studies were executed by local medical centers, including the National Taiwan University Hospital, the Taichung Veterans General Hospital, the Kaoshiung Medical College Hospital and the Tz’uchi Buddhist General Hospital. The study subjects were organised to visit one of the participating hospitals in the morning for history taking, physical examination and laboratory examinations. A questionnaire on medical history, including history of hypertension, heart diseases and operation on cardiovascular system was also completed. Laboratory tests included blood chemistry, urinalysis, electrocardiography and chest and lumbar spine Xray. All the electrocardiograms were interpreted by two qualified cardiologists and all the chest X-ray films were judged by one chest physician. The information was pooled at the steering center located in the National Taiwan University Hospital. In cases where the candidates could not attend the hospital, home visits were undertaken by qualified doctors; history taking and physical examination only were performed. In this communication only the cardiovascular data are presented. The criteria for the diagnosis of hypertension followed that of World Health Organization, i.e., systolic blood pressure $160 mm Hg and / or diastolic blood pressure $95 mm Hg [3]. Those with a definite history of hypertension who were receiving antihypertensive medication at the time of survey were also diagnosed as having hypertension disregarding the blood pressure readings at the time of examination. The diagnosis of coronary artery disease was made if one or more of the following conditions were present: (1) previous definite diagnosis of coronary artery disease, such as history of myocardial infarction, presence of significant coronary lesions by coronary angiography; (2) symptoms of typical angina pectoris; (3) unequivocal electrocardiographic findings of myocardial infarction and / or ischemia. The x 2 test was used for the comparison of data
A total of 2600 subjects (males 1322, females 1278) were included in the study. Among them, 2518 (1283 males and 1235 females) with complete cardiovascular data are included in the present report. The age distribution for both males and females is depicted in Table 1. The age distribution of the males and females was significantly different (P,0.005) with more male subjects distributed to the more elderly group ($75 years of age).
3.2. Hypertension Hypertension was diagnosed in 931 subjects, a prevalence rate of 37.0%. Of those, 686 were diagnosed by elevated blood pressure at physical examination. In the remaining 245 the blood pressure was not elevated at examination but hypertension was diagnosed from the history. Female subjects showed a significantly higher prevalence of hypertension than the males (40.9% vs. 33.2%, P,0.001). In the age group 65–74 years, the rate of hypertension was 40.7% for females and 32.1% for males (P,0.001). The sex difference was not evident for subjects aged 75 years or older (Table 2). Isolated systolic hypertension was the most common form of hypertension (365 subjects, or 53.2% of all hypertensive subjects who had elevated blood pressure at examination), followed by combined systolic and diastolic hypertension (232 cases, 33.8%) and isolated diastolic hypertension (89 cases, 13%). The isolated systolic hypertension was found Table 1 Age–gender distribution of the study subjects Age group 65–74 years Male Female Total
Total $75 years
966 990
317 245
1283 1235
1956
562
2518
* P,0.005 for age distribution between males and females.
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181
179
Table 2 Prevalence of hypertension Diagnosed by physical examination 65–74 years
Diagnosed by history $75 years
65–74 years
$75 years
Male Systolic Systolic1diastolic Diastolic
219 (94) (81) (44)
89 (55) (28) (6)
91
27
Female Systolic Systolic1diastolic Diastolic
297 (159) (101) (37)
81 (57) (22) (2)
106
21
516
170
197
48
Total
to be more prevalent in female subjects (17.5% vs. 11.6%, P,0.001) and also in the subjects aged $75 years than the subjects aged 65–74 years in both sexes (for males, 17.4% vs. 9.7%, P,0.001; for females, 23.3% vs. 12.9%, P,0.02). Antihypertensive therapy was taken by 607 subjects (males, 72.5%; females, 59%; combined, 65.2%), but only 34.3% of the treated subjects had their blood pressure controlled to normal levels.
3.3. Coronary artery disease Coronary artery disease was diagnosed by history and electrocardiograms. One hundred and thirty subjects (male 73, female 57) were diagnosed by history to have coronary artery disease, including 40 with histories of myocardial infarction and 90 with presence of typical angina pectoris. Diagnosis of coronary artery disease was made in another 156 subjects exclusively by electrocardiograms, including changes of myocardial infarction in 147 (male 77, female 70) and of myocardial ischemia in 55 (male 33, female 22). Thus, 286 subjects in total (males 160, females 126) were diagnosed as having coronary artery disease, giving a prevalence rate of 11.4% in our study population. Males and females showed no difference in the prevalence of coronary artery disease (male 12.5%, female 10.2%, P50.07).
3.4. Electrocardiographic findings Electrocardiograms were interpreted as normal in 725 subjects (28.8%). Sinus bradycardia was a
common electrocardiographic finding in our study population (14.9%). Left ventricular hypertrophy was also common (13.3%). Other frequent electrocardiographic changes included myocardial infarction, myocardial ischemia, complete right bundle branch block and various cardiac arrhythmias (Table 3).
3.5. Other cardiovascular diseases There were four subjects who had received permanent pacemaker implantation. Two cases had had operations on abdominal aortic aneurysm. Mitral stenosis was detected in eight subjects and ventricular septal defect in one by physical examination. Congestive heart failure was diagnosed in 83 cases by history taking and physical examination (males 33, females 50; 3.3% of the whole group). Table 3 Electrocardiographic findings
Normal Sinus bradycardia LVH Myocardial infarction Complete RBBB AF /Af Myocardial ischemia LA enlargement Complete LBBB RVH Other arrhythmias (PAC, PVC)
No. of cases
Percentage
725 374 334 147 97 61 55 26 15 7 150
28.8 14.9 13.3 5.8 3.9 2.4 2.2 1.0 0.6 0.3 6.0
Abbreviations: AF, atrial flutter; Af, atrial fibrillation; LA, left atrial; LBBB, left bundle branch block; LVH, left ventricular hypertrophy; PAC, premature atrial contraction; PVC, premature ventricular contraction; RBBB, right bundle branch block; RVH, right ventricular hypertrophy.
180
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181
4. Discussion Cardiovascular disease is one of the leading causes of mortality and morbidity in the modern era, especially for aged people [4–6]. Biostatistic data about the leading causes of death in Taiwan indicated that cardiac diseases ranked in fourth position in past decades [1]. Studies on the prevalence of cardiovascular diseases in Chinese people in Taiwan were sporadic and incomplete [7–9]. The present survey is distinctive in that it was hospital-based and conducted by physicians. Most of the examinees underwent complete history taking, physical examination and extensive laboratory tests. This well-designed, comprehensive large scale survey was expected to give useful information about the health status of the aged population living in this Island. As demonstrated in this study, the prevalence of hypertension in Chinese elderly people was high (37%) which is comparable to that reported for other people [10,11]. Ostfeld reported a prevalence rate of 50% for hypertension in one elderly population [12]. We found that female subjects had a higher prevalence of hypertension than males. This finding was consistent with previous reports [10,11]. It is widely appreciated that isolated systolic hypertension is the most common form of hypertension found in aged subjects [13,14]. Our data support this observation. The high systolic blood pressure is attributed to decreased arterial compliance —a consequence of aging process [14]. Among the hypertensives, antihypertensive therapy was taken by 65.2% subjects, indicating the wide acceptance of antihypertensive therapy by the elderly hypertensive population in Taiwan. But, control of blood pressure to normal level was achieved in only 34.3% of the treated individuals. The reason why more males took antihypertensive regimens was not clear. It was speculated that this might be due to males having more insurance coverage, such as government employees’ and laborers’ insurance. Coronary heart disease is the most important cause of death in the industrialized Western countries, although the incidence is decreasing in certain areas [15–19]. Yet, some countries reported a trend of increasing incidence of coronary artery disease, among them are Soviet Union [20], People’s Republic of China [21] and Taiwan [22]. In our survey, coronary heart disease was detected in only 11.4% of
the elderly Chinese, much lower than that of the US and some European countries. This low prevalence may be explained by the hereditary differences and by the insensitivity of the detection methods we used. Electrocardiograms were interpreted as being normal in 28.8% of our study subjects. This rate was lower than that reported by Campbell et al. [23]. Seventy percent of the electrocardiograms showed various changes. Some of these changes may be related to underlying abnormalities such as hypertension and coronary artery disease while others may be associated with the natural aging process or due to drug effects. As an example, the high prevalence of sinus bradycardia in our population might be partially attributed to the effect of some cardiovascular medicines, such as beta blockers and calcium channel antagonists. In conclusion, from this well organized epidemiologic study, we found that there is a high prevalence of hypertension in elderly Chinese people in Taiwan. Coronary artery disease was also common but the prevalence rate was much lower than that of the Western countries. Other cardiovascular diseases such as aortic aneurysm and valvular heart disease were quite rare in the elderly people. This information is not only useful for medical care of the elderly but may also provide knowledge for comparing cardiovascular diseases between different regions and different people in the world.
Acknowledgements This work was supported by a grant (DOH 80-25) from the Department of Health, Executive Yuan, Republic of China.
References [1] National health Administration, Executive Yuan, Republic of China: Health Statistics: I. Vital Statistics. National health Administration, 1971–1996. [2] Lee TK, Huang ZS, Ng SK, et al. Impact of alcohol consumption and cigarette smoking on stroke among the elderly in Taiwan. Stroke 1995;26:790–4. [3] Hypertension and Coronary Heart Disease: Classification and Criteria for Epidemiological Studies. First Report of the Expert Committee on Cardiovascular Diseases and Hypertension. Technical Report Series, No. 168. Geneva, World Health Organization, 1959. [4] Kohn RR. Human aging and disease. J Chronic Dis 1963;16:5–21.
C. Liau et al. / International Journal of Cardiology 67 (1998) 177 – 181 [5] Uemura K, Pisa Z. Recent trends in cardiovascular disease mortality in 27 industrialized countries. Wld Hlth Statist Quart 1985;38:142– 62. [6] Luepker RV. Epidemiology of atherosclerotic diseases in population groups. In: Pearson TA, Criqui MH, Oberman A, Winston M, editors. Primer in preventive cardiology. Am Heart Assoc, 1994: 1–10. [7] Tsai HC, Yen TS, Wang LT, Cheng JT, Tseng WP, Chen CM. An epidemiologic study of the cardiovascular diseases among the inhabitants of a fishing village in Taiwan. Report I. Blood pressure and hypertension. J Formosan Med Assoc 1966;66:249–58. [8] Tsai HC, Tseng WP, Yen TS, et al. Coronary heart disease and hypertension in Taiwan aborigines. Am J Epidemiol 1967;86:253– 63. [9] Tseng WP. Blood pressure and hypertension in an agricultural and a fishing population in Taiwan. Am J Epidemiol 1967;86:513–25. [10] National Center for Health Statistics: Hypertension and Hypertensive Heart Disease in Adults. Vital and Health Statistics, PHS Publ. No. 1000. Series 11, No. 13, 1966. Public Health Service, Washington, DC, US Government Printing Office. [11] National Center for Health Statistics, Roland M, Roberts J: Blood pressure levels and hypertension in persons ages 6–74: United States, 1976–1980. Advance data from vital and health statistics, No 84, DHHS Publ No (PHS) 82-1250. Hyattsville, MD, Public Health Service, October 8, 1982. [12] Ostfeld AM. Elderly hypertensive patients: epidemiologic review. NY State J Med 1978;78:1125–9.
181
[13] Kannel WB. Systolic blood pressure, arterial rigidity, and risk of stroke. J Am Med Assoc 1981;245:1225–9. [14] Rowe JW. Systolic hypertension in the elderly. New Engl J Med 1983;309:1264–70. [15] Kitchin AH, Lowther CP, Milne JS. Prevalence of clinical and electrocardiographic evidence of ischaemic heart disease in the older population. Br Heart J 1973;35:946–53. [16] National Heart, Lung, and Blood Institute: Morbidity from coronary heart disease in the United States. NHLBI data Fact Sheet, June 1990. [17] Tuomilehto J, Puska P, Korhonen H, et al. Trends and determinants of ischaemic heart disease mortality in Finland: with special reference to a possible levelling off in the early 1980s. Int J Epidemiol 1989;18:S109–17. [18] Beaglehole R, Dobson A, Hobbs MST, Jackson R, Martin CA. CHD in Australia and New Zealand. Int J Epidemiol 1989;18:S145–8. [19] Hatano S. Changing CHD mortality and its causes in Japan during 1955–1985. Int J Epidemiol 1989;18:S149–58. [20] Deev AD, Oganov RG. Trends and determinants of cardiovascular mortality in the Soviet Union. Int J Epidemiol 1989;18:S137–44. [21] Tao S, Huang Z, Wu X, et al. CHD and its risk factors in the People’s Republic of China. Int J Epidemiol 1989;18:S159–63. [22] Liau CS, Hahn LC, Tjung JJ, et al. The clinical characteristics of acute myocardial infarction in aged patients. J Formosan Med Assoc 1991;90:122–6. [23] Campbell A, Caird FI, Jackson FM. Prevalence of abnormalities of electrocardiogram in old people. Br Heart J 1974;36:1005–11.