Public Health

Question 1

Define Incidence and Prevalence

Answer 1

Incidence - New cases in population

Prevalance - population number affected at time

Question 2

Define lead time bias

Answer 2

Pt identified earlier appears to live longer

Question 3

Define length time bias

Answer 3

Diseases slow growing more likely to be identified, therefore giving impression that screening results in higher survival

Question 4

selection bias

Answer 4

error in selection or allocaiton. Proper randomisation not achieved

Question 5

Information bias - measurement, observer, recall, and reporting?

Answer 5

Measurement - Different equipment used
Observer - researcher subconsciously records differently
Recall - Events not remembered correctly
Reporting - Suppression of info, embrassment

Question 6

Publication bias

Answer 6

Negative results less likely to be published

Question 7

Confounding factor

Answer 7

Association can be explained by unmeasured variable

Question 8

Reverse Causality

Answer 8

Outcome causes exposure

Question 9

Give WHO screening criteria for the condition, method, treatment, and screening programme

Answer 9

Condition must be - understood, identifiable latent phase, important health issue

Method must be - suitable to population

Tx - effective and accepted

Programme must be - Cost effective, benefit must outweigh harm (false postitive and negatives)

Question 10

sensitivity vs specificity

Answer 10

Sensitivity - Positive correctly identified

Specificity - negative correctly identified

Question 11

PPV vs NPV?

Answer 11

PPV - Porportion with positive result that have disease

NPV - proportion with negative result that dont have disease

Question 12

What is case control study? pros and cons

Answer 12

case control - cases with conditions vs people without

Pros - Good for rare disease. Quick and cheap

Cons - Prone to selection bias

Question 13

What is cohort study? Pros and cons

Answer 13

Cohort - People followed over time and exposure and disease recorded

Pros - Good for rare exposures. Decrease selection bias

Cons - Time consuming, needs large sample size

Question 14

What is cross sectional study? pros and cons

Answer 14

Cross sectional study - one or more variables studied at one point in time

Pros - Quick, cheap, large sample size

Cons - Risks of recall bias, reverse causality, non-respondance

Question 15

Define primary, secondary, tertiary prevention

Answer 15

Primary - remove risk factors of disaease

Secondary - prevent progression in early stages

Tertiary - Minimise disability in established disease

Question 16

Bradford Hill Criteria?

Answer 16

So Sick And Tired Cant Do Revision
S - Strength of association
S - Specificity
A - Analogy, similarity to other cause effect relaionships
T - Temporality. Exposure before outcome
C - Coherence and Consistency. Logical.
D - Dose response
R - Reversibility

Question 17

Define absolute and relative risk

Answer 17

Absolute - overall likelihood of ocurrence

Relative - incidence in exposed / incidence in unexposed

Question 18

Define economic efficiency

Answer 18

Resources allocated to maximise benefit

Question 19

Define incremental and marginal cost

Answer 19

Incremental - Difference in cost + QALYS between different treatments

Marginal - Cost incurred in producing 1 more unit

Question 20

Health behaviour and illness behaviour

Answer 20

health behaviour - aimed at preventing disease

Illness behaviour - aimed at seeking remedy

Question 21

Theory of planned behaviour

Answer 21

Prediction of behaviour can be attained by intention which itself is determined by attitude, subjective norm (what others think), and behavioural control (I cant quit)

Question 22

Transtheoretical (stages of change) model

Answer 22

Pre-contemplation to contemplation to preparation to action to maintenance

Question 23

Health inequality vs inequity

Answer 23

Inequality - differences in healthcare due to individuality

Inequity - Differences due to injustices