HYPERTENSION BURDEN AND CVD RISK PREDICTION IN AFRICA

WHO Report 2005

Global Cardiovascular Disease Burden 17 million global deaths due to CVD ¾ in Developing Countries

Projected death rates by specific causes for selected countries, all ages, 2005 WHO Report 2005

Challenge of CVD in Africa Double burden of disease Changing pattern of disease and risk factor exposure Infectious disease priorities; constrained budgets Focus on population approaches to prevention Standard surveillance of major risk factors

Challenge of CVD in Africa Prevention and surveillance are particulaly relevant in Africa: In SSA, the need for appropriate care for CVD will place an enormous pressure on the already fragile health care systems and jeopardize the viability of poorly funded public health services Cost-effective strategies are needed and prevention strategies are therefore particularly relevant in resource-poor SSA countries.

WHO Regions Disease burden (DALYs) in 2000 attributable to selected leading risk factors Number of Disability-Adjusted Life Years (000s)

Lancet 2005; 365: 217–23 Rate of HBP, Number of people with HBP, We are 79.8 M and we will be M by 2025 Projections for 2025 based on the assumption that country specific prevalence estimates will remain constant!!!! EPIDEMIOLOGY of HYPERTENSION in Africa

WHO Regions Deaths in 2000 attributable to selected leading risk factors Number of deaths (000s)

Diseases Attributable to Hypertension HYPERTENSION Gangrene of the Lower Extremities Heart Failure Left Ventricular Hypertrophy Myocardial Infarction Hypertensive Encephalopathy Aortic Aneurym Blindness Chronic Kidney Failure Stroke Preeclampsia/ Eclampsia Cerebral Hemorrhage Coronary Heart Disease Adapted from Dustan HP et al. Arch Intern Med. 1996; 156:

HYPERTENSION BURDEN IN Africa Stroke is a major complication of Hypertension in Africa Stroke is a major complication of Hypertension in Africa Lemogoum et al, Am J Prev Med 2005;29 (5SI): Lemogoum et al, Am J Prev Med 2005;29 (5SI): Stroke mortality and case fatality in some Africa Stroke mortality and case fatality in some Africa countries exceed those in the developed world countries exceed those in the developed world Walker et al, Lancet 2000;355: Walker et al, Lancet 2000;355: Hypertension is the most consistent and powerful Hypertension is the most consistent and powerful predictor of stroke and is causally involved in more predictor of stroke and is causally involved in more than 70% of stroke cases than 70% of stroke cases Lavados et al, Lancet 2005; 365: Bronner et al, N Engl J Med 1995;333: Lavados et al, Lancet 2005; 365: Bronner et al, N Engl J Med 1995;333:

Stroke mortality by region (1990) Mortality rate Mortality rate (per 100,000) (per 100,000) Former socialist economies China Established market economies* Sub-Saharan Africa India Middle Eastern Crescent Other Asian countries and islands Latin America *Western Europe, USA, Canada, Australia, New Zealand, Japan Adapted from Reddy KS, Yusuf S. Circulation 1998;97:

Risk of AMI in African region: INTERHEART  578 cases and 789 controls, 9 SSA countries  Blacks (36.3%), Coloured (46.7%), European/Other (17%)  67% of AMI were men  Mean ages: Men 53.2 ± 11.6 yrs; Women 56.4 ± 11.0 yrs  Similar relationships between the common CVD risk factors and AMI as found in the overall INTERHEART Study  Hypertension, Diabetes, Smoking, abdominal obesity and abnormal apoB/ApoA1 ratio provided a PAR of 89.2% for AMI Steyn K et al. INTERHEART AFRICA Study. Circulation 2005; 112(23):

SINGLE RISK FACTOR APPROACH Is it necessary to change paradigm? Clustering of three major risk factors Other risk factors Close association between CVD and diabetes Importance of BP control for outcomes in diabetes Hypertension or diabetes as entry points Pragmatism, PHC, health workers Science (cost effectiveness)

P <0.001 Urban Population Rural Population Obesity: Urban-Rural Population, Cameroon

P <0.001 ** 1 st < nd rd th >0.98 * 1 st < 21.5 kg/m² 2 nd kg/m² 3 rd kg/m² 4 th >25.8 kg/m² Arterial Hypertension : Antihypertensive treatment or screening SBP>= 140 mmHg and/or DBP>=90mmHg Hypertension Prevalence according to Obesity in Cameroon

Projections for the Diabetes Epidemic: Projections for the Diabetes Epidemic: Global SSA

Prevalence of Diabetes: Urban-Rural Population in Cameroon P <0.05 P <0.001 NeverAlways Television Frequency Urban Population Rural Population Diabetes: IDF definition

MULTIFACTORIAL RISK APPROACH Risk is multifactorial. Absolute CVD risk of any one risk factor is determined by the multiplicative effects (total risk) of the other concomitant risk factors. Therefore the intensity of the prevention strategy should be guided by level of absolute multifactorial or total risk. What is my patients total (multifactorial) risk of developing heart attack or stroke? Risk is multifactorial. Absolute CVD risk of any one risk factor is determined by the multiplicative effects (total risk) of the other concomitant risk factors. Therefore the intensity of the prevention strategy should be guided by level of absolute multifactorial or total risk. What is my patients total (multifactorial) risk of developing heart attack or stroke?

Probabilité d’accident 10-Années % SBP Cholesterol HDL-C Diabetes Cigarettes ECG-LVH Kannel. Am J Hypertens. 2000;13:3S-10S. Impact of multiples risk factors on the probability of Coronary Heart Disease: Framingham study

Strategies for prevention  Reducing risk factor availability (primordial prevention)  Reducing prevalence of risk factor exposure (primary prevention)  Limiting the complications of established CVD (secondary prevention)  Only the population strategy is feasible – requires commitment of policy makers

Population based approaches Very cost effective Policies for promotion of Tobacco control Healthy Diet Physical activity

Primary Prevention Interventions with Proven Efficacy Weight Loss Exercise Reduced Sodium Intake Reduced Alcohol Consumption

Population-Based Strategy Hypertension 1991;17(Sup):16–20. Reduction in SBP mmHg % Reduction in Mortality Reduction in BP After Intervention Before Intervention StrokeCHDTotal SBP Distributions