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Pascal Bovet, MD, MPH University Institute of Social and Preventive Medicine, Lausanne

Primary prevention of NCD: population and high-risk strategies - implications for national programs. Pascal Bovet, MD, MPH University Institute of Social and Preventive Medicine, Lausanne Consultant for NCD, Ministry of Health, Seychelles

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Pascal Bovet, MD, MPH University Institute of Social and Preventive Medicine, Lausanne

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  1. Primary prevention of NCD: population and high-risk strategies - implications for national programs Pascal Bovet, MD, MPH University Institute of Social and Preventive Medicine, Lausanne Consultant for NCD, Ministry of Health, Seychelles WHO-IUMSP International Seminar on the Public Health Aspects of NCDs Lausanne, Geneva, 7-12 March 2010

  2. Are NCD/CVD preventable, to which extent? Risk factors of NCD/CVD and their characteristics ‘Population’ strategies and ‘high risk’ strategies Limitations and opportunities for NCD/CVD prevention Conceptual framework for planning NCD/CVD prevention & control

  3. Different CVD rates underlie large potential for preventionTrends in IHD, 1950-1987, age 45-64 Thom et al. NIH Publication 92-3988

  4. Large proportion of CVD deaths occur out of hospital Need for prevention since no possibility for case management McGovern PG et al. Minnesota Heart Survey Inv. Recent trends in acute CHD. NEJM 1996;334:884

  5. Are NCD/CVD preventable, to which extent? • Risk factors of NCD/CVD and their characteristics • ‘Population’ strategies and ‘high risk’ strategies • Limitations and opportunities for NCD/CVD prevention • Conceptual framework for planning NCD/CVD prevention and control

  6. Health promotion, primary prevention and secondary prevention of CVD First event: MI, stroke (1/3 die) Recurrence: MI, stroke, CHF Normal artery Atherosclerotic plaques (starts in children) Risk factors Clinical case management Rehabilitation Clinical case management Rehabilitation Risk factors Risk factors Secondary preventionAvoiding recurrence of disease = management of RF Primary preventionof CVDRF in population (health promotion) = primordial prevention Primary prevention of CV disease in individuals at high risk =screening & treatment Primary prevention of CVD = Avoiding first event

  7. Main risk factors for NCD/CVDUnderlies rationale for prevention strategies) • Non-modifiable RF: • age, sex, history • CVD endpoints: • Isch. heart disease • Stroke • Vascular disease • Heart failure • NCD endpoints: • Some cancers • Respirat. diseases • Renal disease Socio-economic & cultural determinants • Physiological RF: • Hypertension • High cholesterol • Diabetes • Obesity Early life characteristics • Behavioral RF: • Smoking • Unhealthy diet • (salt, sat fat, lack fruit & veg) • Sedentary lifestyle But not RHD, endocarditis, cardiomyopathies

  8. Graded relationship between RF and NCD/CVD « the lower the better » Ann Intern Med.1998;128:81-88.

  9. % CHD SBP No Deaths Rate Relative Excess attributable Per 1000 men risk risk to high BP of CVD 1.00 <110 21,379 202 10.5 0 0 110-119 66,080 658 11.0 1.05 33 1.0 120-129 98,834 1,324 14.3 1.36 376 11.5 130-139 79,308 1,576 19.8 1.89 738 22.6 140 -149 44,388 1,310 27.3 2.60 748 22.8 150-159 21,477 946 38.1 3.63 593 18.2 160 -169 9,308 488 44.8 4.27 319 9.8 170-179 4,013 302 65.5 6.24 221 6.8 8.14 180+ 3,191 335 85.5 239 7.3 Men free of CVD at baseline; excess deaths: difference between observed and expected at lower rate (<110) RR, RF prevalence and attributable fraction for strokeLow impact of strategies targeting high-risk patients 35.1 41.0 23.9 Stamler R. The BP problem: risks and their reduction (MRFIT). Cardiovasc Risk Fact, 1:71-9

  10. Prevalence of RF in population (%) Risk of an event due to RF (%) Distribution of patients with event due to RF 30 25 70% 20 % 15 50% 10 5 0 0 1 2 3 4 5 6 7 8 9 10 Decile of risk factor Wilhelmsen et al. Clin Sci 1979;57:455S Distribution of RF in the population and impact on disease Large proportion of cases arise from majority with low RF level

  11. Multiplicative effect of risk factors on CVD Underlies need for integrated approaches 64 26 10-year risk to have CVD 32 8 SBP (mmHg) Total cholesterol (mmol/l) MRFIT Screenees’ Cohort (figures among smokers)

  12. 31-yr CHD, CVD, and all cause mortality by number of RF: up to 80% CVD cases could be prevented if all persons had 0 RF Daviglus ML, Stamler, et al. Favorable cardiovascular risk profile in young women and long-term risk of CVD and all-cause mortality JAMA. 2004;292:1588-1592

  13. Risk for CVD, diabetes and cancer largely reduced by healthy livingFour healthy behaviors: tobacco, physical activity, diet, overweight (EPIIC–Potsdam, age 35-65 yr, adjusted for SES Ford ES et al. Healthy living is the best revenge. Findings from the European Prospective Investigation Into Cancer and Nutrition–Potsdam Study. Arch Intern Med 2009;169:1355-1362.

  14. Risk factors: characteristics underlying prevention strategies • Continuum relation between RF and NCD/CVD over a wide range (rather than across arbitrary thresholds) • Multiplicative risk arising from combination of RF • Clustering of CVD RF is common due to similar lifestyle associations • In any community, largest number of NCD/CVD events arises from persons with modest RF elevations (not eligible to treatment): • >80% of CVD could be averted if distribution of RF was low in pop. • All people have some level of RF: emphasis on population strategies • Clustering: integrated strategies aimed at multifactorial risk reduction

  15. Are NCD/CVD preventable, to which extent? • Risk factors of NCD/NCD and their characteristics • ‘Population’ strategies and ‘high risk’ strategies • Limitations and opportunities for NCD/CVD prevention • Conceptual framework for planning NCD/CVD prevention and control

  16. Distribution density Risk factor Distribution density Risk factor Approaches to NCD/CVD primary prevention Avoid development of new cases • « High-risk strategy » • Screening & treatment of RF • Targets selected individuals • Individual based “clinical” • Identify people with high risk and treat them (large effect in a few) • Rescue operation (delays consequences) • « Population strategy » • Public health approach • Targets entire population • Interventions outside MOH • Small reduction in entire population (small effect in many) • Radical attempt to deal with underlying causes

  17. Need to tackle «sick» populations, not merely deviant individuals • Root of cholesterol problem lies in a characteristic of the population as a whole • Need to target 'sick populations’, not merely ‘deviant individuals’ (i.e. shift distribution of RF in entire populations) • Response: e.g. North Karelia prevention program Rose G. CHD epidemiology. Oxf. Med Pub 1995

  18. NCD risk behaviors: merely a matter of personal choice? An element of personal responsibility But, also, if we want people to make health choices we have to make healthy choices available

  19. Higher price of cigarettes (i.e. tax) is a powerful measure to curb tobacco use, UK, 1971-96 Central Statistical Office (UK) (1965-97)

  20. Examples of interventions targeting the entire population • Educational interventions • Media, school, workplace • Transportation policies (change environment) • Limit role of automobile (and increase use of buses): promote walking/cycling, pedestrian zones, safe well lit green areas, sidewalks • Health promoting cities and environments • Improve food supply (change environment) • Improve process and manufacturing (salt, trans fat, saturated fats, etc) • Increasing availability and reducing cost of healthy foods • Promoting healthy food choices and limiting marketing to children • Economic policies: incentives and disincentives • Tax on tobacco • Differential taxes for energy dense foods/fruits-vegetables • Initiatives at the community level • Most effective when multifaceted, involving community • Dose of intervention and duration must be large enough Prevention of chronic diseases by means of diet and lifestyles changes. Disease Control Priorities in Developing Countries (DCPC2), World Bank & WHO, 2006

  21. High-risk strategies (who to screen and treat?): Multiplicative effect of concomitant RF on IHD incidence Stamler J. Established major coronary risk factors. In Marmot et al. CHD epidemiology from etiology to public health. OUP, 1992

  22. High-risk strategy: who benefits most from treatment?Need to assess total CVD risk of individuals; reduce NNT RR=2 d: 50 yrs, smoking, high chol. c:40 yrs, high cholesterol b: 40 yrs, smoking a: 40 yrs, no smoking, normal cholesterol RR=2 WHO Expert Committee, Hypertension Control, Technical Report Series 862, 1996

  23. Assessing total CVD risk: the New Zealand guidelines

  24. ESH/WHO stratification of CV risk related to hypertension Refers to 10 year risk of a CV fatal or non-fatal event. Backer G. 2007 Guidelines for the Management of Arterial Hypertension. The Task Force for the Management of Arterial Hypertension of the ESH and the ESC. J Hypertens 2007, 25:1105–1187,

  25. Prescribing treatment is no guarantee of result…

  26. One-year adherence to a 1-tablet/day medication in random sample of newly hypertensive persons(MEMS, Seychelles) 100 Good adherence in only 25% 80 6-7 pills per week 60 Percent of patients (%) 4-5 pills per week 40 0-3 pills per week Dropped follow-up 20 Data not available 0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 Month of follow-up 25% good adherence = maximal yield of a screen/treat strategy at population level. Bovet et al. Monitoring one-year compliance to antihypertension medication in the Seychelles. Bull WHO 2002;80:33-39.

  27. Low treatment uptake 12 months after HBP screening in a random sample of population of Dar es Salaam, Tanzania ~10’000 adults of general population screened for BP 161 with BP >160/95 on 4 visits in 6 weeks Advised to seek HC Follow-up 1 year later Bovet et al. Low utilization of health care services following screening for hypertension in Dar es Salaam (Tanzania): a prospective longitudinal study.BMC Public Health 2008;8:407.

  28. Potential benefit for population vs. high-risk interventions Rose G. CHD epidemiology. Oxf . Med Pub 1995

  29. Decline in CVD in Western countries (1980-2000) was due more to reduction in RF in populations than treatment • Risk Factors worse +17% • Obesity (increase) +7% • Diabetes (increase) +10% • Risk Factors better -65% • Population BP fall -20% • Smoking -12% • Cholesterol (diet) -24% • Physical activity -5% • Treatments -47% • AMI treatments -10% • Secondary prevention -11% • Heart failure -9% • Angina: CABG & PTCA -5% • HBP therapies -7% • Statins (prim. prev.) -5% • Unexplained -9% Ford et al. NEJM 2007; 356: 2388. Capewell S, O'Flaherty M. What explains declining coronary mortality? Lessons and warnings. Heart 2008;94 1105-8.

  30. CHD mortality falls attributed to treatment vs. reduction of risk factors in the population in various countries NEJM 2007; 356: 2388.

  31. Population vs. high-risk approaches: need for both • High-risk and population interventions are mutually supportive • Counseling to high-risk persons extends to relatives, friends, colleagues • Population strategy is essential if attempts of individuals to change their lifestyles are not to turn them into social outcasts (normative role, molding opinions) • High-risk individuals are quantitatively but not qualitatively different people: tail of a continuous distribution of RF Rose G. CHD epidemiology. Oxford Med Pub 1995

  32. High-risk and population approaches

  33. Strategies to prevent NCD/CVD in the population “Primary prevention: avoid occurrence of new cases” • Reduce RF levels in all individuals: population strategy • Create conducive environment enabling adoption of healthy lifestyle • e.g. legislation, tax, financial incentives by government • Small effect in many people but large impact at population level • Do not require behavior change, can be rapidly effective • Often very cost effective (can even generate revenue) • “Good for all” • Detect and treat high-risk individuals : high-risk strategy • Screening (e.g. HBP) and treat before complications occur • Large effect in few people but small impact at population level • Require behavior change at individual level (compliance) • Often costly (drugs for years for lots of patients) • “Good for some”

  34. Are NCD/CVD preventable, to which extent? • Risk factors of NCD/CVD and their characteristics • ‘Population’ strategies and ‘high risk’ strategies • Limitations and opportunities for NCD/CVD prevention • Conceptual framework for planning NCD/CVD prevention

  35. Important issues in NCD/CVD prevention • Cumulative lifelong exposure to RF: start interventions early • Most causes of CVD (“causes of the causes”) lie beyond the health sector: need for multisectoral interventions (partnerships) • Interventions: need for large enough doses and for enough time • Importance of using different settings for interventions • Issue of individual behaviour change vs. structural changes

  36. Challenges for NCD/CVD prevention • Limited data/recognition of magnitude of NCD epidemic - advocacy • Myths: CVD affect the old, the rich, and are personal choices • Double burden of disease: “finish infectious diseases agenda first” • Prevention not given priority vs. treatment (market pressures) • Powerful vested interests (tobacco, food industry, cars, agriculture) • (pop strategy): need to influence policy makers of non-health departments (“politics of prevention”) • (HR strategy): stroke/CHD/HBP/DM considered diseases for specialist • PHC in LMIC not adapted for health care for chronic conditions • High costs of NCD/CVD management & dwindling resources

  37. Are NCD/CVD preventable, to which extent? • Risk factors of NCD/CVD and their characteristics • ‘Population’ strategies and ‘high risk’ strategies • Limitations and opportunities for NCD/CVD prevention • Conceptual framework for planning NCD/CVD prevention

  38. Relation between population strategies and high-risk strategies for NCD/CVD prevention and control Individual-based high-risk strategy: Screening & treatment in high-risk individuals RF & NCD Population strategy (enabling adoption of healthy behaviors): Health education Healthy policy Healthy environment + surveillance of RF for guiding & monitoring interventions

  39. Prevention & control of NCD: a simple framework • Modifiable behaviors: • Tobacco • Physical inactivity • Unhealthy diet • (salt, fats& sugar, fruits/veg) • Patho-physiological RF • Hypertension • High cholesterol • Diabetes • Obesity • IHD • Stroke • Peripheral artery dis. • Heart failure • Other NCD: cancers, etc • Cost effective Rx for acute NCD cases • + Surveillance • Guide & evaluate intervention • Population strategy: • Environment • Policy • Education • High-risk strategy: • Screening and treatment of high-risk individuals for selected conditions Primary prevention (decrease incidence of new cases)

  40. Policy framework for NCD prevention and control(to speed transition to optimal health stage in populations) Reducing energy intake, incr. PA, red. smoking, etc Adapted from: Sacks et al. Obes Rev 2008 (from WHO Global Strategy on Diet, PA and Health: a Framework to monitor and evaluate implementation)

  41. Conclusions • Modifiable RF of NCD are known as well as effective interventions • Apply the knowledge • Need for population approaches (high impact, potentially low cost) • Majority of NCD cases arise from persons with fairly low risk • Prevention is a must as there are insufficient resources to count only on Rx • Most effective PH interventions are outside of health sector • Need for selected high-risk approaches (screen & treat) • High cost, limited efficacy, commercial interests: need for careful selection • Can be good entry points • Multifactorial nature of NCD underlie need for inter-sectoral action, coordination & partnerships

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