assessing health risks in populations - session 12 Flashcards
many diseases, or health conditions are caused by more than one _____
exposure
to prevent diseases and health conditions, public health programs are directied toward ___ or ____ ___ ___
reducing or eliminating causal exposures
epidemiological research focuses on: (2)
- identification of risk factors and risk assessment
- planning and evaluating public health interventions to reduce the incidence of disease in the population
the knowledge created on risk and the magnitude of risk associated with various factors (_____) allows those who are responsible for protecting the public’s health to ________________
exposures
make decisions about allocating scarce resources (e.g. time, energy, and money), where they will have the most impact
risk assessment helps with ___ _____
resource management
for public health decision-making purposes, it is valuable to be able to answer these questions: (2)
- what amount of the risk of developing a disease is attributable to a particular exposure
- by what percentage would the risk of developing disease (e/g/ lung cancer) be reduced if the exposure (e.g. smoking) was eliminated? (in epi we can answer qs like this by measuring magnitude of risk
risk assessment is a central task in ____________
population health research and practice
define risk
risk is the probability that an event will occur
example of risk
there are 100 smokers, if 60 of the smokers develop lung cancer and 40 of them do not, the probability, or risk of developing lung cancer among smokers is 60/100
define risk factors
they are factors, which are statistically associated with the increased risk of a health condition (outcome)
define protective factor
they are factors, which are statistically associated with the decreased risk of a heatlh condition(outcome)
what is a measure of association
quantifying the strength of association between a risk factor and a health condition
what are 5 measures of association?
correlation coefficient. relative risk (RR). odds ratio (OR). risk difference (RD). attributable risk (AR)
define relative risk
it is the ratio of the incidence of an outcome in the presence of an exposure to the incidence of an outcome in the absence of that exposure
the larger the RR, the ____ the ____________
stronger
association between exposure and outcome
see the 2x2 table/contingency table
see it
what is the formula for the incidence of disease among the exposed?
I1 = A/(A+B)
what is the formula for the incidence of disease among the non-exposed?
I0 = C/(C+D)
what is the formula for the relative risk?
RR = I1/I0
do the exercise on page 13
do it
___ is one of the central concerns of epi
causality
in epi we want to be able to claim that a ____ ___ exists between a _____ ____ and a _______
causal association
an exposure factor
a disease (or an outcome)
__________ must be satisfied in order to claim that a causal association exists
several criteria of causality
what are austin bradford hills criteria of causality (9)?
- strength of association
- consistency
- specificity
- temporal relationship
- biologival gradient
- plausibility
- coherence
- experiment
- analogy
strong associations are less likely to be caused by ____
chance
___________ between the exposure and the outcome is a required criterion for causality
evidence of a strong association
describe consistency as a criteria for causality?
- relationships that are confirmed in mustiple studies are more likely to be causal
- look for consistent findngs: across different populations; with different study designs
describe specificity as a criteria for causality?
- easier to support causation when associations are specific
- but this may not always be the case as many exposures cause multiple diseases
describe temporal relationship as a criteria for causality?
- if a factor is believed to cause a disease, then it must necesssarily always precede the outcome
describe plausibility and coherence as a criteria for causality?
- the observed association agrees with currently accepted understanding of pathological and biological processes
- causal mechanism must not contradict what is known about the biology of the disease
describe biological gradient as a criteria for causality?
- there is evidence of a dose-response relationship
- changes in exposure are related to a trend in relative risk
describe experiment as a criteria for causality?
- most often this criteria cant be met
- we cant experiment with human subjects
describe analogy as a criteria for causality?
- relates to the correspondence between known associations and one that is being evaluated for causality (e.g. chemicals with similar molecular structure causing the same cancer)
describe the web of causation
many factors contribute to the development of health outcomes (e.g. chronic conditions)
give two examples of web of causation
- health related behaviours (smoking, physical activity)
- environmental influences (physical environment (e.g. air pollution), social environment (e.g. stressful social relationships))
no single study is sufficient for ______ inference
causal
why is causal inference not a simple process? (2)
because we need to consider the evidence and we need to be able to interpret and scientifically judge evidence
