Cardiovascular Epidemiology and Epidemiological Modelling THE UPSTREAM FACTORS

Cardiovascular Epidemiology and Epidemiological Modelling THE UPSTREAM FACTORS: DIET, PHYSICAL ACTIVITY OBESITY AND DEPRIVATION. Martin O’Flaherty Simon Capewell Division of Public Health University of Liverpool

Overview Upstream and downstream risk factors Links to CVD: The diet link The obesity link The physical activity link

BMI PA Diet 20 -30 years Smoking SBP/DBP LDL/HDL Diabetes (IGT) 10 years Combined CVD risk

Diet and CHD Evidence from basic science, observational studies and trials. Direct effects: diet itself Indirect effects: effects on risk factors

Modifying diet Seven Countries estimates Menotti et al (Seven Countries data) European Journal of Epidemiology 15: 507 -515, 1999.

Modifying diet: Prudent vs Western Relative risk of IHD events by quintiles of diet score Hu et al. American Journal of Clinical Nutrition 1999; 70: 1001

Modifying diet Dietary Approaches to Stop Hypertension Appel et al. NEJM, 1997: 336: 1117

Modifying diet: Salt Cook et al BMJ 2007; 334; 885 -;

Diet SBP/DBP CVD Risk

The National Diet and Nutrition Survey (2002 and 2003); Scientific Advisory Committee on Nutrition (2003); Do. H (2004). www. heartstats. org

Obesity Blood Pressure Blood Lipids CVD Diabetes

Obesity and diabetes link Body mass index at follow-up and relative risk for type 2 diabetes in participants in nurses' health study. Wild, S. H et al. BMJ 2006; 333: 1009 -1011

Obesity and Blood pressure link Increase in mean systolic blood pressure in overweight and obese men and women compared with normal weight individuals. Data from Health Survey for England, 2003 (www. dh. gov. uk) Wild, S. H et al. BMJ 2006; 333: 1009 -1011

Obesity and Blood lipids link Prevalence ratios for hypercholesterolaemia (that is, a doctor's diagnosis or a measurement of ≥ 6. 2 mmol/l) by sex, age, and BMI category. Data derived from cross sectional data from the NHANES III study Wild, S. H et al. BMJ 2006; 333: 1009 -1011

Effects of Weight loss

Obesity and CVD Mortality Reported studies on the association between obesity and mortality: Methodological problems obscuring the relationship direct associations no association non-significant positive associations non-significant negative associations J- and U-shaped associations a significant inverse association Failure to control for the confounding effect of smoking “Inappropriate” control (or over-control) for biologic effects of obesity, such as high blood pressure, elevated TC, and diabetes Failure to eliminate early deaths Lack of long-term follow-up Reanalysis of the Chicago Heart Association study: “In 25 -year follow-up with exclusion of deaths for 0 to 15 years, there was a positive association in all subcohorts, with seven significant, both with and without adjustment for smoking or obesity-related risk factors” Dyer et al. Annals of Epidemiology 2004, 14: 101

Obesity prevalence

Obesity prevalence trends

Children obesity

Physical Activity and Mortality Warburton, D. E. R. et al. CMAJ 2006; 174: 801 -809

Physical activity and CVD mortality Warburton et al. CMAJ 2006; 174: 801

Benefit of Physical activity even in people with risk factors Myers et al N Engl J Med 2002; 346: 793

Physical Activity associated with lower risk factor levels Blood Lipids ↓ Triglicerides ↑ HDL ↓ LDL/HDL ratio Berg A, Halle M, Franz I, et al. Physical activity and lipoprotein metabolism: epidemiological evidence and clinical trials. Eur J Med Res 1997; 2: 259 -64. Decrease Blood pressure Blair SN, Goodyear NN, Gibbons LW, et al. Physical fitness and incidence of hypertension in healthy normotensive men and women. JAMA 1984; 252: 487 -90. Decrease Diabetes incidence Helmrich SP, Ragland DR, Leung RW, et al. Physical activity and reduced occurrence of non-insulindependent diabetes mellitus. N Engl J Med 1991; 325: 147 -52. Laaksonen DE, Lindstrom J, Lakka TA, et al. Physical activity in the prevention of type 2 diabetes: the finnish diabetes prevention study. Diabetes 2005; 54: 158 -65.

Physical activity trends in the UK

Socio-economic inequalities Three fold social gradients in premature CVD mortality rates Partly explained by gradients in smoking and diet Partly other pathways [stress, adrenaline, etc]

North/South Inequalities in CHD men women www. heartstats. org

Our current understanding of CHD causation Deprivation Diet Smoking Direct effect? BMI Blood Pressure Blood Lipids CVD Risk PA Diabetes Upstream Downstream

Proportion of people with 10% CVD Risk within 10 years men Quintiles of the Townsend score Hippisley-Cox, Heart 2007 (Online first)

What proportion of CHD burden could be attributed to Social Class? Attributable fractions Emberson et al. IJE 33 (2): 289. (2004)

Are socially disadvantaged patients getting less treatment? Tudor Hart’s “Inverse Care Law”: Those in need of care, don’t get what they need. Supporting evidence for : GP Prescribing CHD drugs [J Epidemiol Commun Hlth 2004; 58: 89– 96] Revascularization [ Br J Gen Pract 2000; 50: 449; BMJ 1997; 314: 257] Overall management [ Heart 1999 81 252] 81 But inequalities not always found: GP quality of care in Rotherham. [J Public Health (Oxf). 2006 28(1): 39]

Interventions: evidence is sparse Effectiveness of interventions targeted to achieve changes in the upstream risk factors Mostly observational data Few RCTs exist, do suggest benefits from: Weight loss, PA low salt low fat

Summary CVD risk factors and cvd risk paradigm solid Relationships between upstream factors and downstream factors is known We can estimate the effect of changes in their levels in terms of mortality and morbidity Upstream risk factors can influence directly CVD risk and indirectly through downstream risk factors Socioeconomic factors: complex relationship. Direct effect/mediated through risk factor levels Scarce RCT evidence for interventions

Other References references Ministry of Health, Department of Health for Scotland. 1 A national health service. London: HMSO, 1944. (Cmd 6502. ) Department of Health. 2 Failed asylum seekers and ordinary residence—advice to overseas visitors managers. 2008. www. dh. co. uk (search for: 9854). Dixon A, Le Grand J, Henderson J, Murray R, Poteliakhoff 3 E. Is the NHS equitable?