Epidemiology Flashcards
What is epidemiology and why is it needed?
Study of people and the distribution and determinants of health which affect the health outcomes of individuals and populations
Is needed to provide information about health on a population level, to formulate associations and to understand socio-economic effects and make interventions
Results of these studies are used to control health problems
Define incidence (also called cumulative incidence)
No. new cases of a disease/in population at risk x given time period
Define mortality rate
No. deaths in a specified population per unit time
Apply the epidemiological framework to describe why obesity trends have increased since 1980:
Time, person, place
Time:
- people naturally increase in weight over lifetime
- people are living longer (less disease)
- more transport used now and less walking
- more office jobs (static lifestyle)
Person:
- individual eating habits have changed
- less physical activity
- more alcohol
Place:
- more food available, ready meals etc.
- more food advertising
- decreased cost of food
- no food shortage in developed world
Define bias and why is might be responsible for increasing trend seen in obesity
Artefact introduced through the design of a study
Leads to inclination for/against a result which may be considered unfair
Examples in obesity:
1) selection bias -> only people who need medical assistance are registered as obese
2) observation bias -> methods of analysing and classifying obesity have changed over time e.g. BMI
Define confounding and why it might be responsible for increasing trend seen in obesity
Factors which are associated with the exposures and outcomes, but do not directly link the two
E.g. eating food while watching TV, means that physical inactivity is associated with weight gain rather than just no change in weight/no weight loss
What are the different types of prevention?
Primordial: stopping exposure to RF
Primary: protecting against RF (vaccines)
Secondary: detecting disease early and treating it e.g. screening
Tertiary: alleviating symptoms after being affected by an exposure e.g. stroke rehab
Define exposure and outcome
Exposure - a characteristic which you possess which is a determinant of the outcome (e.g. smoking)
Outcomes - all the possible results which stem from exposure to a causative factor (e.g. lung cancer)
What is socioeconomic deprivation and how is it measured?
A continuous spectrum of absolute and relative poverty, which affects health outcomes
Can be measured by Carstairs index, in epidemiological studies
Depends on:
- availability of health services
- learned behaviours
- levels of environmental deprivation
- genetics and physiological influences
What are 4 types of epidemiological studies?
Ecological
Cross sectional
Case control
Cohort
Describe ecological studies (adv and dis)
When units of measurement are larger than the individual, assumes ecological fallacy (that health of a population is representative of the individuals in it) e.g. salt intake in kg/country
Adv: quick, cheap, easy, good when individual data cannot be collected
Dis: not representative of individuals, assumes ecological fallacy
Describe case control studies (adv and dis)
Start with outcome, look back at exposures
Have a control group and an outcome group
Look back at people with say T2DM and see their exposures compared to those without T2DM and see if you can stop the most important exposures
Adv: quick, good for rare outcomes
Dis: recall bias, not good for rare exposures
Describe cohort studies (adv and dis)
Selecting a group of individuals with a particular characteristic and studying them overtime to assess exposures and outcomes
Adv: good for rare exposures, multiple outcomes assessed
Dis: not good for rare outcomes, you need a control group and often hard to find a balanced one
- susceptible to drop out
Describe cross-sectional studies (adv and dis)
Sampling individuals at one point in time and assessing their exposures and outcomes simultaneously
Longitudinal - repeated overtime
Adv: quick, cheap
Dis: not good for disease with short time between exposure and death, recall bias, sample selected is not always representative
Describe the Dahlgren and Whitehead 1992 model
There are 4 levels to the determinants of health:
1) Individual (non-modifiable) = age, gender, hereditary factors
2) Lifestyle (modifiable) = diet, exercise…
3) Social environment = friends, family, work
4) Physical environment = pollution, availability of health services etc.
