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Clinical and epidemiological approaches to the life course Shah Ebrahim Department of Epidemiology & Population Health London School of Hygiene & Tropical.

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Presentation on theme: "Clinical and epidemiological approaches to the life course Shah Ebrahim Department of Epidemiology & Population Health London School of Hygiene & Tropical."— Presentation transcript:

1 Clinical and epidemiological approaches to the life course Shah Ebrahim Department of Epidemiology & Population Health London School of Hygiene & Tropical Medicine

2 Overview Clinical perspectives and applications –Service organisation –Health promotion Epidemiological perspectives –Theoretical models –Fetal growth –Economic hardship –Childhood diet –Clinical and preventive applications

3 What is a life course approach for clinicians Taking a social history Measuring growth trajectories in childhood Importance of continuity of care Milestones: birth, school, job, marriage, children, retirement, death Understanding that the patients current experience is rooted in earlier experiences of health care

4 Clinical perspectives Services are organised to reflect lifecourse (obstetrics, child health, adult medicine, geriatrics) BUT, this fragments understanding of health problems in families and communities Primary care can (used to?) take a cradle to grave perspective

5 WHOs policy on ageing has adopted a life course approach http://www.who.int/hpr/ageing/

6 A life course approach in epidemiology investigates the long term effects on health and chronic disease risk of physical and social hazards during gestation, childhood, adolescence, young adulthood and later adult life (and across generations). It studies the biological, behavioural and psychosocial pathways that operate across the life course and influence the development of chronic diseases. What is a life course approach?

7 ...recent progress has shown a) that the health of the adult is dependent upon the health of the child.....[and]....b) that the health of the child is dependent upon the health of the infant and its mother. George Newman 1914 CMO Board of Education

8 Theoretical life course models Critical and sensitive period models with or with out later effect modifier Ben-Shlomo & Kuh 2002 Accumulation of risk with independent and uncorrelated insults with correlated insults risk clustering chains of risk with additive or trigger pathways

9 Critical and sensitive periods Critical period – a time period only during which an exposure has an effect. –Thalidomide and limb abnormalities –Oestrogen use in early pregnancy and vaginal cancer Sensitive period - a time period during which an exposure has a greater effect than outside this period –Learning a second language in childhood –Clinical disease associated with infectious disease exposure

10 Theoretical life course models Critical and sensitive period models with or with out later effect modifier Ben-Shlomo & Kuh 2002 Accumulation of risk with independent and uncorrelated insults with correlated insults risk clustering chains of risk with additive or trigger pathways

11 TIME Accumulation model – independent risks A C B OUTCOMEMEASUREOUTCOMEMEASURE Kuh et al (In Press) A=inactivity, B=high blood pressure, C=high blood cholesterol

12 TIME Accumulation model – risk clustering ACB OUTCOMEMEASUREOUTCOMEMEASURE D Kuh et al D = Metabolic syndrome

13 Chains of risk The impact of some factor in childhood may lie less in the immediate behavioural change it brings about than in the fact it sets into motion a chain reaction in which one bad thing leads to another, or, conversely, that a good experience makes it more likely that another one will be encountered. Rutter 1988

14 TIME Chains of risk model – additive ACB OUTCOMEMEASUREOUTCOMEMEASURE Kuh et al A=Drinking, B=high blood pressure, C= depression

15 TIME Chains of risk model – trigger ACB OUTCOMEMEASUREOUTCOMEMEASURE Kuh et al A=house dust mite, B= asthma attacks, C = school absence

16 Lifecourse influences on respiratory disease (Ben-Shlomo & Kuh 1999) Poor childhood SES Poor educational attainment Poor adult SES Infant Respiratory Infections Poor growth in utero Poor lung development Air pollution Passive smoking Poor nutrition Childhood chest illness Air pollution Poor adult diet Smoking Rapid decline in lung function/ adult lung disease Occupational hazards Asthmatic tendency or Genetic predisposition

17 Interactions between intra-uterine and later life exposures

18 CHD Incidence by Birthweight and BMI: The Caerphilly Study (Frankel et al 1996) BMI TERTILE Percent p=0.5 p=0.0005

19 Accumulation of risk across the life course

20 Odds ratios for disability in 1994 by economic hardship between 1965 and 1983 Lynch JW et al, New Eng J Med, 1997:337:1889-95 IADL ADL

21 Poor health at age 33 & cumulative SES (birth - 33yrs) Source: Power et al, 1999 best worst

22 The Boyd-Orr Study: long term follow up from childhood, 1937

23 Energy intake in childhood and cancer risk: Boyd Orr study Cause of deathHazard ratio (95% CI) All causes1.04 (0.99, 1.09) Cancers not smoking related 1.20 (1.07, 1.34) Cancers smoking related1.09 (0.96, 1.23) Other causes0.99 (0.93, 1.05) Frankel et al, BMJ 1998

24 Household income, 1937/9 and walking speed in 2003, mean age 70 Time to walk 6m. Weekly household income, 1937/9 3.2% reduction in walking time per category increase in income, p=0.04 highlow

25 Clinical and public health applications

26 Schematic representation of the life course of ventilatory function taken from Strachan (1997) Years of life Level of lung function 0102030405060708090100 0 10 20 30 40 50 Level below which symptoms may occur Critical period Sensitive period Determinants of loss Determinants of gain

27 Life course development in physical capacity and effects of a threshold for independent living. Age Physical capacity Threshold for independent living

28 Life course development in physical capacity and effects of a threshold for independent living. Age Physical capacity Threshold for independent living Reducing the threshold for older people

29 Life course development in physical capacity and effects of a threshold for independent living. Age Physical capacity Threshold for independent living 1 2 3 4 1 = Early life interventions to ensure max. peak capacity 2 = Adult interventions to slow rate of decline in capacity 3 = Late life interventions to maintain capacity above thresholds 4 = remedial therapy to restore quality of life

30 Life course epidemiology Extends the fetal origins of adult disease hypothesis Greater explanatory power than simpler causal models Provides a means of developing novel prevention strategies

31 Conclusions Clinical perspectives on life course could dramatically influence health promotion activities Epidemiological perspectives are leading to new understanding of aetiology which is fundamental to development of successful preventive programmes A life course approach emphasises that opportunities for prevention are not confined to any one period Evaluations of the effects and costs of interventions at different points in the life course are needed


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