What is epidemiology?
scientific discipline studying the incidence, distribution, and control of disease in a population. Includes the study of factors affecting the progress of an illness, and, in the case of many chronic diseases, their natural history. - Objectives of descriptive epidemiology - to evaluate trends in health and disease and allow comparisons among countries and subgroups within countries - to provide a basis for planning, provisions and evaluation of services - to identify problems to be studies by analytical method
What are the types of epidemiology?
- Descriptive - Tell us how things are distributed
- Analytical - Exploit those distributions to ask questions - Experimental - Change those distributions ourselves
- Descriptive studies are relatively inexpensive and less time consuming than analytical studies
who gets sick
where rates are higher/lowest
temporal patterns of disease;
o seasonality
o secular trends which are affected by;
changes in diagnostic techniques
changes in the accuracy of the denominator data
changes in the age distribution of the population
changes in survival from improves treatment or disease mutation change sin actual disease incidence
- Prevalence studies measure disease and exposure simultaneously in a well-defined population - Advantages - prevalence studies cut across the general population, not simply
those
- seeking medical care
- they are good for identifying the prevalence of common outcomes, such as arthritic, blood pressure or allergies
- Limitations - you cannot determine whether exposure preceded disease
- since you determine prevalent rather than incident cases, results will be
influenced by survival factors
- Correlational studies (ecological studies) use measures that represent characteristics of entire populaions to describe outcomes in relation to some factor of interest such as age, time, utilization of services or exposure
- Advantages - You can generate hypitheses for case-control studies and environmental studies
- You can target high-risk populations, time-periods or geographic regions for future studies.
- Limitations - because data are for groups, you cannot link disease and exposure to individuals
- you cannot control for potential confounders
- data represents average exposures rather than indicual exposures, so you cannot determine a dose-response relationship
- caution must be taken to avoid drawing inappropriate conclusions.
How do you measure prevalence?
Number of people with disease at anuy point in time / total population
What factors influence prevalence?
- Prevalence Increased by;
longer duration of the disease
increase in new cases (increase in incidence)
in-migration of cases or susceptible people
out-migration of healthy people
improved diagnostic facilities
- Prevalence Decreased by;
shorter duration of disease
high case-fatality
decrease in cases
in-migration of healthy people
out-migration of cases
improved cure rate of cases
What is the incidence rate?
Number of new cases of disease in a period / number initially free of disease
- N.B. In dynamic populations we have a problem as our denominator (the number at changes over time
Describe the epidemiology of smoking.
- What proportion of the UK population smoke? 27% of 16 years and older
- What have been recent trends in smoking prevalence? Seems to have leveled out at current levels. No real decrease since the early 90s. There has been an increase in women smoking but generally more men than women smoke.
- What are the general health effects of smoking?
lung cancer and other cancers
stroke
peripheral vascular disease
birth defects of pregnant smokers’ offspring
Buerger’s disease (thromboangiitis obliterans)
impotence
chronic obstructive pulmonary disease, emphysema and chronic bronchitis in particular
- How does smoking vary across gender, age and social position in the UK? - Higher socio- economic groups are less likely to smoke. Smoking is most prevalent among people aged 25-34
risk)
years, followed by those aged 15-24 years, and those aged 35-54. Older people aged 55 and over are much less likely to smoke and have experienced the greatest decline in smoking prevalence over the past 15 years. Smoking prevalence has been similar for both sexes since the mid-1980s. In 2002, the rate was 25 percent for males and 24 percent for females. Females are slightly more likely than males to smoke at ages 15-34, but for those aged 35 and over, smoking has generally been more prevalent among males; over the 1990s, both sexes became less likely to smoke.
Describe the concepts of normality.
- How is a 95% reference range calculated? Two standard deviations from the mean
95% probability that the true value lies within the interval
- Could you discuss the difficulties raised by classifying individuals, behaviour etc. as abnormal? You get negative results such as labeling and stigma. Normal and abnormal are subjective judgments. How can we decide what it normal and abnormal?
- Can you give examples of the concepts of ‘labeling’ and ‘stigma’? Negative attitudes drive stigma. Access to services and historical/religious perspectives e.g. possessed by demons therefore “bad” people, should they be treated. Late 1800s saw “moral” treatment of mental health cases. Frank Bruno and the media “Bonkers Bruno Banged Up”.
What is stigma?
Stigma - Deliberate exclusion of certain types of person – inflicted social pain – due to either physical or social attribute
- Enacted stigma - Discrimination by others
- Felt stigma - Fear of actual (enacted stigma)
- Passing - Concealment of ‘invisible’ stigma (e.g. HIV, mental illness) - Covering- Concealment of ‘visible’ stigma (e.g. eczema)
- Consequences Of Stigma - Shame, embarrassment - Avoid public places
- Social isolation
What is Health Promotion?
Any combination of health education and related organisational, political and economic interventions designed to facilitate behavioural and environmental adaptations which will improve or protect health
(Anderson, 1983 – WHO)
What are the different approaches to health promotion?
- Medical – focuses on disease and prevention
- Behavioural – focuses on attitudes and lifestyles
- Educational – focuses on knowledge and decision making - Client-centred – focuses on empowering individuals
- Societal – focuses on political and social action
- Beattie’s Typology – Approach to Health Promotion
- Contrasts authoritative and negotiated health promotion
- Contrasts individual and collective focus
- 4 Segments divided by two axis: Legislative action, community development, personal
counseling and health persuasion
- Primary Preventative Medicine – Screening risk factors, health protection and health education. Aim is to prevent onset of disease.
- Secondary Prevention – Detect and cure disease at an early stage. E.g. cancer screening
- Tertiary Care – Minimise the effects or reduce the progression of irreversible disease. E.g false teeth, hip replacement, palliative care, drug treatment for AIDS.#
- What agencies, organisation and individuals are involved in health promotion in the UK? GPs, NHS and Department Of Health, Central and local government, Locally based initiatives such as food cooperatives and credit unions, community workers, health action zones, Surestart, neighborhood renewal, Media
Outline the scale of social inequalities in health in the UK
- Background of health inequality in the UK - By 1970s evidence that the UK was being
overtaken in health indicators (infant mortality, expectation of life) by other countries.
- Labour launches Black Committee inquiry in 1977 (Sir Douglas Black (Chief Scientist), Jerry Morris (Professor of Community Health), Cyril Smith (SSRC) and Peter Townsend (Professor of Social Policy and Chair of CPAG)
- Inequalities in Health presented to Tory Minister Patrick Jenkins in 1980.
- 260 duplicated copies printed, no press release, distributed to a few journalist at
August Bank Holiday!
- Published by Penguin – now in many editions
- Not until 1990s that ONS encouraged to investigate Variations (sic) in Health
- At the heart of the agenda
published in
1997.
ealth published in 1998.
•Now a key feature of the NHS plan 2000 – targets for tackling inequalities set. •November 2002 report Chief Medical Officer Progress Report
•Tackling Health Inequalities: A Programme for Action was launched in July 2003
- Can you give some examples of what is meant by social inequalities in health?
- Routine manual workers have a much higher chance of infant mortality than the
population as a whole. - Mortality from injury and poisoning is much higher in children from social group 5
- Teenage pregnancy is much more common amongst lower social groups. Inequality can
be measured through the Gini Coefficient. The ration between the Lorenz Curve and a perfect distribution (straight line) is the Gini Coefficient.
- Is health getting more or less equal in the UK? Health inequalities are increasing as the gap between the “rich” and “poor” or the “haves” and the “have nots” increases. Since 2001/2002 indicators have shifted towards more equality.
What are the possible causes for health inequalities?
- What explanations have been suggested for social inequalities in health?Black report suggested that problems are structural. main debate is whether problems are behavioural or structural. As health increases people move up through social classes. As class has no causal significance class could be seen to be caused by class. Natural or social selection e.g. social Darwinism. Richest people are healthier, choose healthier partners and have healthier offspring. Materialist idea: Poverty causes ill health through diet, environment, working conditions etc. Cultural ideas: is culture a response to structure or does it exist independently? Wilkinson Hypothesis: Inequality generates ill health.
]
- What approaches have been suggested to reduce social inequalities in health? Reduce poverty and inequality and need to improve targeting of health expenditure towards children and public health.
