HYPERTENSION BURDEN AND CVD RISK PREDICTION IN AFRICA

1. HYPERTENSION BURDEN AND CVD RISK PREDICTION IN AFRICA

2. WHO Report 2005

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

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

7. 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

8. 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 .

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

10. EPIDEMIOLOGY of HYPERTENSION in Africa Projections for 2025 based on the assumption that country specific prevalence estimates will remain constant!!!! Rate of HBP, 2000 - 2025 Number of people with HBP, 2000 - 2025 We are 79.8 M and we will be 150.9 M by 2025 Lancet 2005; 365: 217–23

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

12. Diseases Attributable to Hypertension Left Ventricular Hypertrophy Heart Failure Gangrene of the Lower Extremities Myocardial Infarction Hypertensive Encephalopathy Aortic Aneurym HYPERTENSION Coronary Heart Disease Blindness Cerebral Hemorrhage Chronic Kidney Failure Preeclampsia/Eclampsia Stroke Adapted from Dustan HP et al. Arch Intern Med. 1996; 156: 1926-1935

13. HYPERTENSION BURDEN IN Africa • Stroke is a major complication of Hypertension in Africa Lemogoum et al, Am J Prev Med 2005;29 (5SI):95-101 • Stroke mortality and case fatality in some Africa countries exceed those in the developed world Walker et al, Lancet 2000;355:1684-87 • Hypertension is the most consistent and powerful predictor of stroke and is causally involved in more than 70% of stroke cases Lavados et al, Lancet 2005; 365:2206-15. Bronner et al, N Engl J Med 1995;333: 1392-400

14. Stroke mortality by region (1990) Mortality rate (per 100,000) Former socialist economies 192.35 China 112.12 Established market economies* 98.02 Sub-Saharan Africa 76.25 India 72.89 Middle Eastern Crescent 65.08 Other Asian countries and islands 51.34 Latin America 28.49 *Western Europe, USA, Canada, Australia, New Zealand, Japan Adapted from Reddy KS, Yusuf S. Circulation 1998;97:596-601

15. 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):3554-61

16. SINGLE RISK FACTOR APPROACHIs 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)

17. Obesity: Urban-Rural Population, Cameroon P <0.001 P <0.001 P <0.001 30.3 18.1 P <0.001 P <0.001 Urban Population Rural Population

18. Hypertension Prevalence according to Obesity in Cameroon P <0.001 P <0.001 * 1st < 21.5 kg/m² 2nd 21.6-24.2 kg/m² 3rd 24.3-25.7 kg/m² 4th >25.8 kg/m² ** 1st < 0.86 2nd 0.87-0.91 3rd 0.92-0.97 4th >0.98 Arterial Hypertension : Antihypertensive treatment or screening SBP>= 140 mmHg and/or DBP>=90mmHg

19. Projections for the Diabetes Epidemic: 2003-2025 Global SSA

20. Prevalence of Diabetes: Urban-Rural Population in Cameroon P <0.05 Urban Population Rural Population TelevisionFrequency P <0.001 Diabetes: IDF definition Never Always

21. 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?

22. Impact of multiples risk factors on the probability of Coronary Heart Disease: Framingham study 40 21 Probabilité d’accident 10-Années % 14 10 6 4 SBP 150-160 + + + + + + Cholesterol 240-262 - + + + + + HDL-C 33-35 - - + + + + Diabetes - - - + + + Cigarettes - - - - + + ECG-LVH - - - - - + Kannel. Am J Hypertens. 2000;13:3S-10S.

23. 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

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

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

26. Population-Based Strategy Reduction in SBP mmHg 2 3 5 SBP Distributions Before Intervention After Intervention Reduction in BP % Reduction in Mortality Stroke CHD Total -6 -4 -3 -8 -5 -4 -14 -9 -7 Hypertension 1991;17(Sup):16–20.