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Primary prevention of NCD (focus on CVD)

This article discusses the preventability of non-communicable diseases (NCDs), with a focus on cardiovascular disease (CVD). It explores the risk factors associated with NCD/CVD, including population and high-risk strategies. The limitations and opportunities for NCD/CVD prevention, as well as a conceptual framework for planning prevention and control, are also highlighted.

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Primary prevention of NCD (focus on CVD)

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  1. Primary prevention of NCD(focus on CVD) Pascal Bovet, MD, MPH University Institute of Social & Preventive Medicine, Lausanne Consultant for NCD, Ministry of Health, Seychelles WHO-IUMSP International Seminar on the Public Health Aspects of NCDs Lausanne, 10-18 August 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. 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

  5. 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

  6. 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

  7. 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 Primordial preventionof CVDRF in population (health promotion) = primary prevention of RF Primary prevention of CV disease in individuals at high risk Primary prevention of CVD = Avoiding first event

  8. 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 Not RHD, endocarditis, cardiomyopathies

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

  10. % CHD SBP No Deaths Rate Relative Excess attributable men per risk risk to high BP 1000 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. Cardiovasc Risk Fact, 1:71-9

  11. 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

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

  13. Risk factors: main characteristics • 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

  14. 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

  15. 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 • 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 • Small reduction in entire population (small effect in many) • Radical attempt to deal with underlying causes

  16. 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

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

  18. “Affluenza” and “coca-colonization”

  19. 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”

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

  21. 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

  22. 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

  23. High-risk strategy: who benefits most from treatment?Need to assess total CVD risk of individuals 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

  24. Assessing total CVD risk: the New Zealand guidelines

  25. 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,

  26. Prescribing treatment is no guarantee of result…

  27. 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.

  28. 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.

  29. High-risk and population approaches

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

  31. What explains sharp decline in CVD in Western countries?USA, 1980-2000 • 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.

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

  33. Population vs. high-risk approaches: need for both • High-risk and population interventions are mutually supportive • High-risk counseling 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 • 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

  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: doses need to be large enough (hence multiple) and for enough time • Importance of different settings • Issue of individual behaviour change vs. structural changes

  36. NCD/CVD control through primary prevention: Some limitations in developing countries • Limited data/recognition of magnitude of NCD epidemic - advocacy • Myths that CVD are diseases of the old, the rich and 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) Failure to influence policy makers and policy of non-health departments • (HR strategy) Stroke/CHD/HBP/DM considered diseases for specialist • PHC not adapted for basic health care for chronic conditions • High costs of NCD/CVD management & dwindling resources • Lack of global funding for NCD (vs CD): need to build the case

  37. NCD/CVD prevention & control in developing countries • Good news • Levels of some risk factors still low in some countries • Knowledge for effective prevention interventions is available •  to western countries: CVD epidemics understood at its peak and addressed mainly through clinical management • Prevention (CVD) likely to be less costly than case-management • Bad news • Levels of RF already high and rise steeper in many LIC • Rapid demographic transition (aging populations): NCD inevitable • Global epidemic of “diabesity” (“toxic environment”)

  38. 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

  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 Primary prevention (decrease incidence of new cases)

  40. Conclusions • Distribution of NCD (CVD) results from balance between favorable factors (NCD related policy and health care) and unfavorable factors (demography, obesogenic toxic environment, etc) • NCD (particularly CVD) are largely preventable and effective interventions are known for both PH and individual based interventions • Largest number of NCD/CVD cases result from persons with fairly low levels of RF: importance of public health approaches • Numerous challenges related to long-term individual-based interventions targeting high-risk individuals: issues of screening & cost effectiveness • Population strategies have the largest potential impact (small change in population vs. large change in a few individuals)

  41. 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

  42. State Non-Communicable Diseases Control Programme Surveillance of Risk factors- Tobacco, Alcohol, Diet, Physical Inactivity Policy Primary prevention National initiative Health Promotion Taxation Legislation Risk reduction-Tobacco cessation, Counseling, Diet Guidelines, Abn Lipids, Hypertension Disease specific programmes- at District Hospital level CANCER DM HT A/c MI COPD Early detection Early detection Early detection Immediate intervention Early diag CYTOLOGY EBM EBM EBM EBM EBM Insulinavailability Compliance to trtmnt Prevent relapse Prevent compli PAIN & PALL Care Prevent complications Rehab Rehab

  43. 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)

  44. Natural history of NCDs People without NCD Un-diagnosed NCD Diagnosed NCD High Risk Low Risk

  45. Much lower CVD risk in individuals with healthy lifestyles * Proportion of all CVD events that could have been prevented if all women were in low risk group Stampfer et al. N Engl J Med 2000;343:16-22. (Primary prevention of IHD through diet and lifestyle - Nurses’ Health Study, 89141 women)

  46. Narrowing (“stenosis”) of arteries (“atherosclerosis”): the common characteristic of all cardiovascular diseases

  47. Natural history of cardiovascular disease: long evolution without symptoms Age Artery Symptoms atherosclerosis /signs None 20 y None Risk factors 40 y None 50 y Stroke 50 y + Heart attack + 1 sec MI: 1/3 sudden †

  48. Distribution density Risk factor Examples of population strategies for primary prevention of CVD (and other NCD) • Environment shaping • Sidewalks, safe public green areas, cycling lanes, pedestrian zones • Improving available diet • Alter food content (salt, sugar, trans-fatty acids) • Regulations • Labeling food content • Fiscal incentives/disincentives for production/trade of healthy/unhealthy foods • Advertising of junk foods on TV, vending machines in schools • Tobacco: increasing taxes, smoke free areas, ban on advertising

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