Modules 1 & 2 Flashcards
(32 cards)
screening criteria
disease
test
treatment
screening programme
Bradford Hill criteria
temporality biological gradient reversibility consistency of association specificity biological plausibility strength of association
what is a suitable disease (screening)
be of public health importance
- common
- uncommon but early detection can lead to a better outcome (simple treatment)
known history of disease/risk factors
- can detect risk factors/early forms of disease
- has a long pre-clinical phase - long time to detect.
what is a suitable test?
reliable safe simple affordable acceptable accurate
sensitivity
likelihood of a +ve test in those with a disease
true +ve)/(all w/ disease
specificity
likelihood of a -ve test in those without disease
true -ve)/(all w/o disease
PPV
probability of having disease if you test +ve
true +ve)/(tested +ve
NPV
probability of not havig disease if you tested -ve
true -ve)/(tested -ve
lead time bias
false impression of increased survival time due to an increase in the time between diagnoses and death compared to clinical diagnosis. Patients may not live longer, instead, they simply know that they have the disease earlier, so live with this knowledge for a longer period of time
length time bias
false impression of increased average survival time as screening is more likely to detect a greater proportion of those with a slower progressing form of the disease than a fast progressing form of the disease. thus average survival time of the screened people is skewed and not representative of all the cases, and gives a false impression of survival time.
suitable screening programme?
- benefits > harm
- RCT evidence proves increased survival time/decreased mortality rate.
- cost effective
- adequate resources and policy for testing/diagnosis/treatment/program management
- health system must be able to support ALL elements of this pathway
- must be able to reach those who benefit from screening the most.
factors to consider in prioritisation
evidence measures
community values and expectations
human rights/justice
evidence measure types
descriptive - what is the burden of disease? who has it? trends?
explanatory - where are we now? who is affected most?
evaluative - determinants? risks? why are we getting better/worse? why are there differences in populations?
ottawa charder 3 basic strategies
enable
advocate
mediate
enable
create opportunities for individuals to make healthy choices
allow access to life skills, supportive environments and information
advocate
create supportive environments (political, social, physical, economic, cultural)
achieve equity
mediate
bring people with different opinions together to come to a compromise for health care.
ottawa charter 5 priority action areas
- develop personal skills
- strengthen community action
- create supportive environments
- reorient towards primary healthcare
- develop healthy public policy
high risk individual benefits
high individual/physician motivation
cost-effective (only those that need treatment are treated)
appropriate to individuals - tailored to need.
high benefit-risk ratio
high risk individual intervention disadvantages
high cost of screening
temporary effect - doesn’t address underlying causes
limited potential - high risk doesn’t mean large burden
behaviorally inappropriate.
population intervention benefits
radical - addresses underlying causes
behaviorally appropriate
potential to benefit everyone.
population intervention disadvantages
low benefit-risk ratio
low individual/physician ratio
reduced individual benefit
strengths RCT’s
minimises confounding - diff characteristics have equal chance of being allocated to either EG or CG. therefore similar baseline characteristics. no other different confounding factors
weaknesses RCT’s
maintenance error
highly motivated individuals not representative
costly –> so small study prone to random error
