The epidemiology of hypertension in South America - Nature

Journal of Human Hypertension (2002) 16 (Suppl 1), S3–S6  2002 Nature Publishing Group All rights reserved 0950-9240/02 $25.00 www.nature.com/jhh

The epidemiology of hypertension in South America P Pramparo Cordoba 2962 3G-(1187), Buenos Aires, Argentina

Although cardiovascular disease (CVD) is the leading cause of death and disability in the majority of the countries in Latin America we have few data about regional differences on this topic. Developing countries have scarce epidemiological data on cardiovascular (CV) risk factor prevalence and subsequently in their control and treatment. The load of the CV risk factors, especially hypertension, remains uncertain. The methodology of investigation varies from country to country and the criteria to define ‘hypertension’ is different according to the survey year. Data on CVD from USA and Europe

have been extrapolated to our continent but recently two large epidemiological studies have been conducted in the southern region: FRICAS, primary prevention, and PRESEA, secondary prevention. The first pointed out the importance of each cardiovascular risk factor, including hypertension, in the development of acute myocardial infarction (AMI), and the second showed the poor control of them and the necessity to improve them. Journal of Human Hypertension (2002) 16 (Suppl 1), S3– S6. DOI: 10.1038/sj/jhh/1001331

Keywords: cardiovascular risk factors; primary prevention; secondary prevention; acute myocardial infarction

Conference summary Scientific evidence has shown the importance of hypertension in the development of heart and cerebro-vascular disease, and heart and renal failure. The known risk factors, age and gender, are directly associated with hypertension but other factors such as ethnicity, education and socioeconomic status also have a role in the course of hypertension and in coronary heart disease.1 The relationship of psychosocial characteristics and environmental factors with hypertension has not been conclusively documented. Despite the significant advances made in developed countries in the early detection and proper treatment of hypertension, the number of patients under control is scarce.2 Developing countries have many other difficulties besides the control and treatment of cardiovascular disease (CVD), and in the control of risk factors. The load of the CV risk factors, especially hypertension, in most of the Latin-American countries remains uncertain owing to the scarcity of information on cardiovascular morbidity and risk factors. Local epidemiological data are isolated or not comparable because the information was collected by different organisations (government, ONG etc), with disparity about criteria, objectives, resources, and interests, etc. The analysis of the official data on ischaemic heart disease, stroke, heart failure and renal failure reveals that CV mortality has declined in some areas of Correspondence: Palmira Pramparo, Cordoba 2962 3G-(1187), Buenos Aires, Argentina

Latin America. The prevalence of ischaemic heart disease has decreased significantly in the USA, Argentina, Canada and Chile, while it remains steady or increased slightly in the rest of the Americas with differences by gender. The InterAmerican Heart Foundation has published the book ‘Heart Disease and Stroke in the Americas 2000’ that compiles reliable data regarding CVD mortality and prevalence of CV risk factors, including hypertension, in most of the American countries.3 Table 1 shows the comparative prevalence of hypertension and mortality rate for some countries in the south cone of South America. Note that the methodology of investigation varies from country to country and the criteria to define ‘hypertension’ is different and according to the year’s survey. The largest epidemiological study ‘FRICAS’ (Factores de Riesgo Coronario en America del Sur) has shown the importance of known cardiovascular risk factors in the development of coronary disease.4 This study, based on a case-control protocol, was designed to examine analytically coronary risk factors initially in Argentina, but other countries such as Mexico, Venezuela and Cuba were subsequently incorporated. The purpose of the study was to collect local information, since the data currently available came from the US and European studies, and cannot always be extrapolated to our continent. The Argentine section has been completed, with 1060 patients and 1050 controls enrolled from 1991 to 1994; their results have been published in national and international journals.4–6 The prominent findings can be summarised as

Epidemiology of hypertension in South America P Pramparo

S4

Table 1 Prevalence of hypertension and proportional mortality rates for CVD in some South American countries

% Hypertension M Argentina Bolivia Brazil – Rio Grande do Sul Brazil – Sao Paulo Brazil – Rio de Janeiro Chile Paraguay Uruguay

Proportional mortality from diseases of the circulatory system relative to mortality from defined causes

F

28.5% 23.5% Variable data from 6.09% to 11.06% 10% 13.7% 15.8% 7.3% 22.6% 26.8% Valparaiso city: 11% 26.8% 39.1% 14.99% 19.13%

Crude mortality rates/100 000 population, from hypertension

M

F

M

F

36.6% –

40.6% –

14.05 –

14.1 –

29% for all Brazil

38% for all Brazil

34.7 for all Brazil

28 for all Brazil

– 5.47 –

– 7.76 –

27% 31.8% 34.7%

Adapted from: Wielgosz AT et al, ‘Heart Disease and Stroke in the Americas 2000’ InterAmerican Heart Foundation.

Figure 1 FRICAS study. Prevalence and risk of AMI in hypertensive patients.

follows: hypertension is the major risk factor for acute myocardial infarction (AMI), with a 2.7 odds ratio for hypertensive individuals, as compared with those who were not hypertensive (Figure 1). Differences in relative risk are also seen between men and women (Figure 2). The association of hypertension

and tobacco increased seven-fold the risk for AMI. The risk increased by six-fold when hypertension plus cholesterol greater than 240 mg/dl was present, and by more than four-fold for hypertension and diabetes. It is to be noted that passive smokers were found to have a 1.7 odds ratio for MI, which

Figure 2 FRICAS study. Prevalence and risk of AMI in hypertensive patients by gender. Journal of Human Hypertension


S5

Figure 3 Acute myocardial infarction. Differences between women and men. Basal characteristic and evolution in the unit care.

mounted to 3.2 when associated with hypertension.4–6 Other studies have been published that show the importance of hypertension in women, specifically after menopause.7–9 One study pointed out the role of hormone replacement therapy and their different oestrogen-progestin combination used in hypertensive menopausal women.7,8 Dr Ciruzzi et al have evaluated the course of AMI in women and the study showed that hypertension and diabetes were significantly more frequent in women with AMI than in men. The most common complication in the course of AMI was heart failure due to aging and more frequent anterior MI found in women9 (Figure 3). Subsequently, the InterAmerican Heart Foundation is running a campaign in Latin American and Caribbean countries to promote the early detection and proper treatment of cardiovascular risk factors in women with special focus on hypertension, at any age. A guide and recommendations for promoting women’s CV health are recently published and spread out in scientific sessions.10,11 The recommendations and guidelines given by local and foreign scientific societies for the management and treatment of hypertension have reached our countries.2,12 However, these scientific evidences are not widely used in general practice because of biases, misinterpretations, limitations, oversimplification or undue generalisation of evidence. These realities were shown in numbers from the PRESEA TRIAL (Prevencion Secundaria en Argentina). In the first part of the study, researchers evaluated the clinical records of 2007 patients hos-

pitalised in 54 coronary care units for diagnosis of angina, AMI, first angioplasty or first bypass surgery. In the second part, up to 2 years after the event, a medical interview was carried out with 1399 of those patients. Results showed that the diagnosis of hypertension was not registered in the clinical records in 11.3% of the patients admitted in hospitals. At the interview, 45.5% of the patients (secondary prevention), had blood pressure levels greater than 140/90 mm Hg, among the other non-controlled risk factors.13 Efforts have to continue in improving the quality of life and treatment in hypertensive patients. Much greater effort has to be taken in collecting epidemiological data in Latin American countries on CV risk factor prevalence and CVD according to local characteristics such as ethnicities and population habits. Reliable data would simplify policy and access to care for more people in this part of the world.

References 1 Winkleby M et al. Ethnic and socioeconomic differences in cardiovascular disease risk factors. Finding for women from the Third National Health and Nutrition Examination Survey, 1988–1994. JAMA 1998; 280: 356–362. 2 The Sixth Report of the Joint National Commitee on Prevention, Detection. Evaluation, and Treatment of High Blood Pressure (JNC VI). Arch Intern Med 1997; 157: 2413–2446. 3 Wielgosz AT et al. Heart Disease and Stroke in the Americas 2000. InterAmerican Heart Foundation, Journal of Human Hypertension


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Dallas, 2000. 7272 Greenville Avenue, Dallas – Texas75231-4596 USA. Ciruzzi M et al. Estudio FRICAS. Factores de riesgo para infarto agudo de miocardio en la Argentina. Rev Argent Cardiol 1996; 64: 10– 40. Ciruzzi M et al. Case-control study of passive smoking at home and risk of acute myocardial infarction. Argentine FRICAS (Factores de Riesgo Coronario en Ame´ rica del Sur). J Am Coll Cardiol 1998; 31: 797–803. Ciruzzi M et al. Frequency of family history of acute myocardial infarction Frequency of family history of acute myocardial infarction in patients with acute myocardial infarction. Argentine FRICAS (Factores de Riesgo Coronario en Ame´ rica del Sur). Am J Cardiol 1997; 80: 122–127. Pramparo P et al. La menopausia como factor de riesgo cardiovascular: valoracio´ n del tratamiento de sustitucio´ n hormonal. Rev Argent Cardiol 1998; 66: 75–85. Urthiague ME, Balestrini AE, Pramparo P. Progestins

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