Public Health

Question 1

What is prevalence

Answer 1

• Number of population affected by a conditon, burden of a disease
• Number of cases/ number of population
• Point prevalence = number cases at speciric point in time / number pop at same time
• Period prevalence = number cases in specific time period / n populaiton same time period
• Lifetime prevalence = number cases at some point (in their life) has had condition/ n pop (at risk in their lifetime)

Question 2

What is incidence

Answer 2

• Number of population newly affected by a condition, risk of disease
• Incidence = number new cases/ number population
• mainly interested a sproportion of people
• Cumulative incidence - nnumber new cases over specific period/npopo (at risk over same time)
• Incidence rate = number of new cases per person time. (N new cases/n pop)/time period.

Question 3

What is a case?

Answer 3

• Types: Possible case, Probable case, Confirmed case
• We must define a case to measure it.
• Whatever is chosen, must be explained and justified.
• Defintiion should be: reproducible, clear, specific, measurable,

Question 4

What is population

Answer 4

• “population at risk” - those who might develop a specific illness
• Need a clear definition eg, Place, time, demographics, defining event.
• 2 kinds popiulation:
  
  • Fixed - specific criteria - membership permanent eg, attended specific event, born a certain time
  • Dynamic - more flexible - membership based on current status eg, lives in specific city,studying at uni now.

Question 5

Methods of counting cases and population?

Answer 5

• Count - basic integerm no informative
• Percentage - raw integer into %, provides context and can be changed to fit population count but might change across population sizes
• Ratio - one count divided by another.
• Rate - element of time - how many cases over set period of time

Question 6

Rates and risks used in stats

Answer 6

• Prvelaence and incidence
• Probability
• Absoloute risk
• Attributable risk
• Number needed to treat
• Relative risk
• Odds ratio

Question 7

Absolute risk

Answer 7

• Prevalence and incidence rates
• Now vs unit time

Question 8

Attributable risk (risk difference, excess risk)

Answer 8

• Difference beween two probabilities
• Exposed group vs unexposed group
• Positive intervention = AR reduction
• Negative intervention = AR increase

Question 9

Def of number needed to treat

Answer 9

• number of patients you need to treat to prevent one additional bad outcome (or harm if reversed)
• 1/attributable risk reduction

Question 10

What is the absoloute risk of death, attributable risk and NNT

Answer 10

Question 11

What os the relative risk and odds ratio?

Answer 11

Question 12

working out risks

Answer 12

Question 13

mortality rate and crude mortality rate

Answer 13