Living and dying: Health, Illness & Disease
(and why you need to think about what they might be) R. Fielding Dept. Community Medicine
Learning objectives
• Compare and contrast the concepts of health, illness and disease. • Describe the epidemiological transition • Analyse factors linking environmental and medical outcomes
A. Health & Disease
• Health
– Economic definitions (e.g. Marx) – “Activity”-based definitions (e.g. Parsons) – Wholistic definitions (e.g. W.H.O.) – an absolute or a relative concept? – Quality of Life definitions
• Disease
– bio-pathology – discontinuity (physical, behavioural, phenomenological). – deviation. – systems “flag”.
B. Normality and abnormality
• Statistical definition of disease parametric “indicators” (usually biological variables) exceeding some statistically determined cut-off. • Extreme values are taken as indicators of disease, even though they may just be extreme values.
DBP - Stroke relationship
350 300 250 200 150 100 50 0 <60 60- 70- 80- 90- 100- 110- 120 130 D.B.P. deaths/1000/year
Disease as abnormality
• Probabilistic approach to disease. • Indicator implies disease risk = p. • Does not easily accommodate chance results nor systems variability in Rx and outcome. • Allows estimations of attack rates / Rx benefits
Disease as abnormality (2)
• A view of disease that is limited by being
– person-centred – temporaly bounded – discontinuous.
• However, in reality,
– most disease is either self-limiting, or chronic – most due to behavioural/ lifestyle – reflect community or group “problems” as much as “individual” problems in terms of causes, spread, costs and consequences.
Illness - not disease nor sickness
• Subjective state of “unwellness” • Independent of physical abnormality • More important determinant of consultation than physical state • Has complex psychosocial components
Relation between illness & disease
Feels unwell Feels well
Abnormality Absent Abnormality Present
Illness only
Healthy
Disease and Disease only illness
Why is an understanding of this disease-illness relationship important?
• Health and disease are value judgements based on more than study of reactions. • Illusion that doc. and patient have the same expectations about conduct, behaviour and outcomes • “In reality there are no diseases, there are only sick patients.”
Why is an understanding of this disease-illness relationship important?
• Important implications for type and level of interventions used, for definition and evaluation of outcomes. • Not all diseased patients seek treatment • Not all patients seeking treatment are diseased • Many presenting problems are not “biological”.
Conclusions
• Health is multifaceted • Disease probabilistically defined and measured, with associated problems • Most healthcare demand is driven by illness, not disease; most disease is either self-limiting or incurable. • Limited model distracts from most effective approach to intervention and most economic use of resources
The epidemiological transition
C. Leading causes of death, HK.
1912
Plague T.B. Pneumonia Smallpox Paralysis / convulsion Malaria Diarrhoea Developmtl Old age Unknown
1948
Pneumonia T.B. Enteritis Perinatal Ill-defined Violence Heart Cancer G.U. Digestive
1999
Cancer Heart CVD Pneumonia Injury and poisoning Nephritis Diabetes M Septicemia Liver Aortic Aneurysm (TB)
379 239 238 121 119 92 82 81 76 71
175 109 98 67 45 43 32 22 19 18 (0.414)
10,977 5,220 3,491 2,977 2,053 1,168 725 412 399 324 312 5.0
rate/1,000 7.8
Expectation of life at birth, men, 1871-1971 (UK)
80 75 70 65 60 55 50 45 1871 40 35 1901 1931 life expectancy trend
1871
1901
1931
1961
Source: Lancet, 9/8/86
Questions
1. How has mortality changed in HK since 1900? 2. Why have these changes occurred? 3. What does this tell us about the important influences on mortality? 4. How should we be spending our health budget?
1. How has the pattern of mortality changed?
• From acute to chronic degenerative causes and (in children and younger adults) accidents. • Life expectancy at adulthood little changed, but childhood survival improved during last 100 years.
How has mortality changed? (cont.)
• Infectious disease mortality declined before causes (and Rx) were identified, –so medical interventions not responsible –what else happened in Europe 1830-1930 and HK 50 years later?
2. What has contributed to these changes? (a)
• Changes in the nature of work • Food hygiene laws, improved income => better nutrition • Infrastructure development =>
– better living conditions – clean drinking water – sewage disposal
Systems (not diseasesystems) model of disease
• Unified treatment of disease manifestations • Deteminants of disease viewed as transactional - not simply bounded by organ or body • Fits broader health problems such as substance abuse and violence as well as organic abnormalities
2. What has contributed to these changes?(a)
• Decline in fertility rate altered family size, birth spacing and age distribution; => • increase in median age of infection and lower case fatality rate; => • More children survived, so the mean age of the population increased.
Expectation of life at birth, men, 1871-1971 (UK)
80 75 70 65 60 55 50 45 1871 40 35 1901 1931 life expectancy trend 1961
1871
1901
1931
1961
Factors linking environment to medical outcomes
2. What has contributed to these changes?(b)
• From W.W.II onwards change in activity levels: less manual labour more motorized transport.
• Increases in
– disposable income – food availability & marketing strategies – dietary and other substance intake
Mortality from coronary heart disease, men (20-64) UK
Professional Managerial Skilled nm Skilled m Part skilled Unskilled
0
50
100
150
200
250
300
European age-standardized mortality rate/100,000
2. What has contributed to these changes?(b)
• Increase in body mass (DM, CHD, HT) • Tobacco / alcohol use / environmental degradation > rise in chronic disease prevalence. • Economic developments, loss of control, competitiveness.
3. What does this tell us about important influences on mortality?
• Improvements in life expectancy small despite massive expenditure on health care delivery. • Most mortality declines due to economic, cultural, behavioral and domestic changes • Societal, cultural and behavioural influences have been more important that medical care.
4. How should we be spending our health budget to improve health further?
• Many current causes of mortality incurable. • Prevention best approach to further reductions in mortality • Economic and occupational improvements are among most important developments. • Environmental degradation (consumer behaviour) is now most important threat.
What determines health?
• Is individual behaviour or social class important?
– place of birth – gender – family income – education – activity level – diet – smoking
Is it just up to individuals?
• • • • • housing. food availability, accessibility, labeling. protection from unhealthy advertising. environmental protection opportunity for work & adequate income. • control over one’s circumstances
Why are individuals implicated?
• Governments can avoid addressing structural issues, such as housing supply or unemployment. • Current models of disease see the individual as the unit of pathology, and pathology focuses on biological level only. • Hence, responsibility for health becomes the individual’s and not the state’s.
• Focus on intervention is at the individual, curative level, not the group preventive level. In HK 90% of the health budget goes to the HA, only 10% to the DoH. • Macro-economic models perpetuate this. • Individuals “regulate” themselves, carry the cost, and take the blame.
Main determinants of longevity
• Old grand/parents • Regular and sustained exercise • Diet: high fruit/vegetable/complex carbohydrates, low animal and fats • No smoking or passive smoking
Conclusions
• Economic/political, social & individual behaviour impacts on environment and behaviour, disturbing systemic homeostasis (ecosystem), • result is increased risk exposure and heightened vulnerability.
Conclusions
• Mortality primarily influenced by socioeconomic factors through opportunity and personal behaviour. • Future declines in mortality will derive mostly from social-level changes (e.g. legislation on drink-driving, smoking, pollution, education) and personal behaviour. • Preventive measures offer better value for money.