Measuring Health and Disease Flashcards
Define prevalence.
What is it useful for?
- The proportion of people in a
population of known size who have a
particular disease at a specified point in
time, or over a specified period of time. - Useful for planning services.
= All cases / Population at risk.
Define incidence.
- The number of new cases over
a period of time in a population of known
size.
= Number of new cases / Population at risk.
List 5 reasons for measuring health.
1 - To find prevalence / incidence.
2 - To identify longitudinal trends in disease.
3 - To identify differences in disease patterns between different populations or locations.
4 - To improve service planning (prevalence!).
5 - To measure the effectiveness of interventions.
List 7 sources of information for health status.
1 - Census.
2 - Death certifications.
3 - Health Survey for England (HSE).
4 - General Lifestyle Survey.
5 - Hospital Episode Statistics (for health service usage).
6 - General practice research databses, e.g. CPRD, THIN.
7 - Regional audits / surveys.
List 7 key statistics that are commonly used in measuring health and disease.
1 - Birth rates.
2 - Total fertility rates.
3 - General fertility rate
4 - Incidence.
5 - Prevalence.
6 - Crude mortality rates.
7 - Standardised mortality rates.
Define birth rate.
The number of live births per 1000 population.
Define general fertility rate.
The number of live births per 1000 women aged 15-44.
Define total fertility rate.
The average number of children that a woman would bear if they experienced the age-specific fertility rates at that point in time.
List 3 reasons for measuring infant mortality.
1 - Highly correlated with expectation of life.
2 - Highly correlated with overall economic status.
3 - High infant mortality rates are amenable to change through public health measures:
- Care of pregnant women.
- Infant immunisation.
- Nutrition programmes.
Define crude mortality rate.
- Crude mortality rate = total number of deaths in 1 year / total mid-year population.
Define mid-year population.
The mean of the population on 1 January and the population on 31 December of a year.
List 3 disadvantages of using mortality data as a measure of population health.
1 - Potential for error.
2 - Death may result from many diseases acting in conjunction.
3 - Some diseases have high mortality rate and death occurs quickly, whereas others are long-term and resource intensive but rarely cause death.
List 4 advantages of using mortality data as a measure of population health.
1 - It is a legal requirement in the UK to register each death.
2 - There is little delay in collection of data.
3 - International classification of diseases ensures comparability.
4 - Cheap source of health data.
What is direct standardisation?
- Where age-specific rates from a study population are applied to a standard population.
- Used to answer the question “what would
be the death rate in the standard
population if it had the age-specific death rates experienced by the population I
am looking at?”.
List 2 advantages of using direct standardisation.
1 - Can be used to compare disease rates across areas and time.
2 - Can be used to assess the relative burden of different diseases in one population.
List 2 disadvantages of using direct standardisation.
1 - Requires age-specific rates, which are not always available at a local level.
2 - Rates may not be stable for a small number of events.
What is indirect standardisation?
- Where age-specific rates from a standard population are applied to a study population.
- Used to answer the question “what would
be the death rate in the population i am looking at if it had the age-specific death rates experienced by the standard population?”.
List 2 disadvantages of using indirect standardisation.
1 - Areas cannot be directly compared.
2 - Does not give an idea of the actual burden of disease.
List 5 possible explanations for the association between socioeconomic deprivation and health.
1 - Artefacts of measurement error (minor).
2 - Social selection (minor).
3 - Behavioural / cultural (major).
4 - Psychosocial (major).
5 - Material / structural conditions (major).
Define artefact.
Where observed associations are not genuine, but exist because of the ways in which we measure health and deprivation.
Define social selection.
Where health determines socio-economic status (rather than where socio-economic status determines health).
List 3 behavioural / cultural factors that are a disadvantage to health.
People in deprived areas are more likely to:
1 - Smoke.
2 - Eat poor diets.
3 - Not exercise.
Describe the general psychosocial theory for the association between health and socioeconomic deprivation.
The stress of working in poorly paid, low status jobs with little autonomy creates biological changes in the body, which in turn creates patho-physical changes.
Define social capital.
The amount to which people are connected within their community through relationships and have a shared sense of identity.
Give an example of an advantage of indirect standardisation.
Doesn’t require age specific rates for the study population (as rates from the standard population are being applied to the study population, then absolute values of observed vs expected are compared).
What is a standardised mortality ratio (SMR)?
Standardised mortality ratio = observed number of deaths in study population / expected number of deaths in study population.
