CPH - Epidemiology (Whincup) Flashcards
Appreciate the potential value of studying health and disease in populations. (5)
Population approach can show you:
- How much impact a disease /ilness has on health in community/population in terms of mortality and
morbidity - BUT clinical iceberg
- who may be at risk by seeing how illness varies between people/ places/ periods
- potential causes on wider scale
- how we can prevent disease
- management on population level - service optimisation, interventions
Define the terms epidemiology and public health
Both population level
Epidemiology - Study of the distribution and determinants of health and disease in human populations
Public health - Science & art of prolonging life, preventing disease, promoting health at pop level by organised efforts of society
Explain the concepts of rates and risks as a tool for the study of disease in populations
Rate = number of cases / population at risk
Incidence rate = new cases of disease
Prevalence rate = presence of disease (new and old)
Mortality rate = occurrence of death
Be aware of major differences in disease risks over time and between places.
PLACE - prevalence of a disease can vary in different countries, regions, boroughs, neighbourhoods
TIME - short and long term (seasons vs years)
Types of studies to measure differences between places (2)
Ecological study can look at population/community, to compare exposures and disease rates in different geographies
Best when causal factors are fairly consistent within population (not between populations being studied)
ECOLOGICAL FALLACY - Assumes that exposure and outcome are related in individuals (but it’s based on population data), may be CONFOUNDING factors
Migration studies assess whether differents are due to adult environment or genes / early environment
PITFALLS - Selection bias (are the people who migrated the same as the people in the original country), information bias (do migrants and non-migrants share info in the same way), potential influence of stress of migration
Pitfalls of studying disease between places
PITFALLS - Are the geographical differences real? Differences in ASCERTAINMENT of medical care, differences in DIAGNOSIS (customs, equipment), differences in RECORDING information, differences in POPULATION STRUCTURE (age, gender, etc.) - can take into account, standardise diagnosis / recording, use population-wide surveys and more objective measures
What is seen when measuring over time? (two effects)
Period effect - related to a recent time period / cause
Cohort effect - related to the time of birth / early life cause
What is the ecological fallacy?
Assumes that exposure and outcome are related in individuals (but it’s based on population data), may be CONFOUNDING factors
What are the potential pitfalls when studying disease over time?
PITFALLS - Changes in ASCERTAINMENT, changes in DIAGNOSIS, changes in RECORDING of information, changes in POPULATION STRUCTURE - overcome with complementary study relating potential disease CAUSE to the disease outcome in individuals
Be able to interpret geographic and temporal variations in disease, distinguishing between artefactual and real differences
Be careful of confounding factors
Further research required to overcome confounding and identify individual / causal relevance in some studies
Possibly use criteria for causality?
Appreciate the potential value of variations in disease risk to our understanding of disease causes and treatment patterns
May be able to identify causes and protective features of particular areas / cultures
Understand how changes at a particular moment may have an effect on that birth cohort OR on everyone living during that period
Describe the importance of high blood pressure and its health consequences
Why is high blood pressure an important problem? Strongly associated with higher risks of CVD, CHD and stroke AND risk associated is very common in general population (BOTH SERIOUS AND COMMON)
(And how do we know high BP is bad - cohort studies looking at relationship between high BP and developing disease / dying)
Outline the main risk factors and causes of high blood pressure
Secondary - specific medical cause (about 1% of general population)
May be caused by coarctation of aorta, renal disease, adrenal diseases, pregnancy, drugs
Essential / primary - no specific medical cause
High BMI, alcohol intake, salt intake, low potassium, low fibre/high fat diet, physical inactivity, stress
Risk factors - older age, African-Caribbean, Family history, high BMI, high alcohol intake, NOT SEX/GENDER
Explain the epidemiological basis underlying strategies for treatment of high blood pressure.
Greater BP reduction gives greater reduction in relative risk, due to common nature of high BP and negative implications, risk of CVD is still high even below treatment thresholds so we need….
POPULATION strategy - shift BP distribution with public policy intervention (treatment for high BP, treatment only for those with high CV risk, reduce salt in diet - manufacturing)
Be able to define the terms relative risk and attributable risk and appreciate their relevance to high blood pressure
RISK = PROBABILITY OF AN EVENT (# cases / # at risk)
RELATIVE - Ratio of risk - Risk in exposed group (high BP) / risk in unexosed group (normal BP)
ATTRIBUTABLE (excess risk) - Difference in risk - Risk in exposed - risk in unexposed
