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

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

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.

Expectation of life at birth, men, (UK) Source: Lancet, 9/8/86

Age-standardized annual mortality rates (UK)

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 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 disease- systems) 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, (UK)

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

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 socio- economic 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.