Clin. Epi. Frequency of Disease/Risk/Prognosis

Question 1

describe the ways to calculate mortality rates

Answer 1

Question 2

describe prevalence

Answer 2

proportion of the population at a given time that has the factor of interest

P = number of cases / size of population

Question 3

contrast point vs. period prevalence

Answer 3

• point prevalence: useful in comparing different points in time to help determine whether an outbreak is occurring
• period prevalence: prevalence during a specified period or span of time

Question 4

what is the equation for prevalence?

Answer 4

P = # of cases / size of population

P = I x D

Question 5

describe calculating risk vs odds

Answer 5

Question 6

describe odds ratio

Answer 6

• an odds ratio (OR) is a measure of association between an exposure and an outcome
• the OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occuring in the absence of that exposure

OR = ad / bc

Question 7

describe relative risk

Answer 7

• the relative risk is important as a measure of the strength of the association, which is a major consideration in deriving causal inferences
• if a positive association exists between the exposure and the disease, we would expect that the proportion of the exposed group in whom the disease develops (incidence in the exposed group) would be greater than the proportion of the non-exposed group in whom the disease develops (incidence in the non-exposed group)

Question 8

summarize calculating RR vs OR

Answer 8

Question 9

describe attributable risk

Answer 9

• attributable risk, which is defined as the amount or proportion of disease incidence (or disease risk) that can be attributed to a specific exposure
  
  • for example, how much of the lung cancer risk experienced by smokers can be attributed to smoking?
• the attributable risk may be more important in clinical practice because it addresses a different question: how much of the risk (incidence) of disease can we hope to prevent if we are able to eliminate exposure to the agent in question?

Question 10

give the equation for attributable risk and attributable risk fraction

Answer 10

Question 11

describe relative risk reduction

Answer 11

Question 12

describe absolute risk reduction

Answer 12

Question 13

describe number needed to treat vs number needed to harm

Answer 13