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Clinical and epidemiological approaches to the life course

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Presentation on theme: "Clinical and epidemiological approaches to the life course"— 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 WHO’s policy on ageing has adopted a life course approach

6 What is a life course approach?
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.

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 Accumulation of risk with independent and uncorrelated insults with correlated insults “risk clustering” “chains of risk” with additive or trigger pathways Ben-Shlomo & Kuh 2002

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 Accumulation of risk with independent and uncorrelated insults with correlated insults “risk clustering” “chains of risk” with additive or trigger pathways Ben-Shlomo & Kuh 2002

11 Accumulation model – independent risks
TIME O U T C M E A S R A A=inactivity, B=high blood pressure, C=high blood cholesterol B C Kuh et al (In Press)

12 Accumulation model – risk clustering
TIME O U T C M E A S R D A B C D = Metabolic syndrome Kuh et al

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 Chains of risk model – additive
TIME A=Drinking, B=high blood pressure, C= depression O U T C M E A S R A B C Kuh et al

15 Chains of risk model – trigger
TIME A=house dust mite, B= asthma attacks, C = school absence O U T C M E A S R A B C Kuh et al

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

17 Interactions between intra-uterine and later life exposures

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

19 Accumulation of risk across the life course

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

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

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 death Hazard ratio (95% CI) All causes 1.04 (0.99, 1.09) Cancers not smoking related 1.20 (1.07, 1.34) Cancers smoking related 1.09 (0.96, 1.23) Other causes 0.99 (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. 3.2% reduction in walking time per category increase in income, p=0.04 high low Weekly household income, 1937/9

25 Clinical and public health applications

26 Schematic representation of the life course of ventilatory function
Determinants of loss 50 40 Determinants of gain 30 Level of lung function 20 Level below which symptoms may occur 10 Sensitive period Critical period 10 20 30 40 50 60 70 80 90 100 Years of life taken from Strachan (1997)

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

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

29 Life course development in physical capacity and effects of a threshold for independent living.
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 Physical capacity 2 1 3 Threshold for independent living 4 Age

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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