Population health Flashcards
(32 cards)
What is the aim of intention to treat analysis in a clinical trial?
Reduce selection bias
How is rate of a disease development calculated?
(new cases) / (total person time of follow up)
How is relative risk calculated?
What does it tell you?
(Risk exposed) / (Risk unexposed)
Re/Ru
indicates the relative magnitude of change in risk/rate of outcome, associated with exposure
What is the aim of blinding in a clinical trial?
Reduce information/observor bias
How is attributable risk percentage calculated?
What does it tell you?
AR% = (Re - Ru)/Re x 100
Proportion of incident disease among exposed people that is due to exposure
What is the aim of randomisation in a clinical trial?
Reduce influence of confounding variables
How is risk calculated?
(Number of new cases in a defined period) / (population at risk)
How is attributable risk calculated?
What does it tell you?
(Risk exposed) - (risk unexposed)
Ru-Re
indicates the absolute magnitude of change in risk/rate of outcome, associated with exposure
What is the downside of intention to treat analysis in a clinical trial?
Underestimates treatment effect
How is population atributable risk percentage calculated?
What does it tell you?
100 x (Rt-Ru)/Rt
Proportion of incident disease among whole population that is due to exposure.
How is population attributable risk calculated?
(Rate in whole population) - (Ru)
What are the 3 essentail features of a clinical trial?
Randomisation
Blinding (aka masking)
Intention-to-treat analysis
What are the 9 Bradford Hill Criteria for causality?
temporal relationship
strength
dose-response relationship
consistency
plausibility
exclude alternatives
experimental evidence
specificity
coherence
How is NNT calculated?
1 / (absolute rate/risk reduction)
How is sensitivity calculated?
_ True positive _
True pos + False Neg
How is positive predictive value calculated?
_ True positive _
True pos + False Pos
How is specificity calculated?
_ True negative _
True neg + False pos
How is negative predictive value calculated?
_ True negative _
True neg + False Neg
What are the axes of a receiver operating characteristic curve?
y = sensitivity
x = 1 - specificity
What is the main purpose of a meta-analysis?
To increase power
What should you consider when wondering if a study is relevant to your patient?
PICOT
Population
Intervention
Comparator
Outcome
Time
What are the 4 elements of autonomy in medical ethics?
Freedom to make your own decisions. No coercion No manipulation No deceit
What percentage of travellers visiting a developing country will develop a health problem?
50%
What is the most common cuase of death in travellers?
Cardiovascular disease
