Incidence, prevalence, relative risk, and odds ratio as cloze cards with each formula and variable defined.
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- Incidence measures the number of ____ cases of a disease occurring in a population during a specified time period.
- new
- Cumulative incidence = number of new cases during a time period divided by ____.
- the population at risk at the start of the period
- Incidence rate (incidence density) = number of new cases divided by ____.
- total person-time at risk
- What is person-time?
- The sum of the amount of time each individual in a population was at risk and under observation (e.g., person-years).
- Prevalence measures the proportion of a population that has a disease at a given point or period, including both ____ cases.
- new and pre-existing (old)
- Point prevalence = number of existing cases at a specific point in time divided by ____.
- total population at that time
- Period prevalence = number of cases existing at any time during a specified interval divided by ____.
- the average (or mid-interval) population during that interval
- In a population at steady state, prevalence is approximately equal to ____ (P is approximately I x D).
- incidence rate multiplied by average duration of disease
- Name one way prevalence can increase without any change in incidence.
- Improved survival or treatment that lengthens the average duration of disease.
- In calculating incidence, the population at risk in the denominator should exclude people who already ____.
- have the disease
- Relative risk (risk ratio) compares the risk of disease in the ____ to the risk in the unexposed group.
- exposed group
- Relative risk = risk of disease in the exposed group divided by ____.
- risk of disease in the unexposed group
- What does a relative risk of 1.0 mean?
- No association: the exposed and unexposed groups have the same risk of disease.
- What does a relative risk greater than 1.0 mean?
- The exposure is associated with an increased risk of disease.
- What does a relative risk less than 1.0 mean?
- The exposure is associated with a decreased risk of disease (a protective effect).