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45 Cards in this Set
- Front
- Back
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What type of study do you use to look at the association between a risk factor and an outcome?
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Cohort studies (a type of observational study which is a type of analytical study)
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How do you calculate the odds ratio of something?
How do you interpret this? |
Expected outcomes/Unexpected outcomes
=(cases with exposure * controls without exposure) / (cases without exposure * controls with exposure) "The odds of getting disease A are [OR] times higher in those with exposure to factor X than in those without exposure to factor X" |
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How do you characterize the amount and distribution of disease within a population?
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Descriptive studies
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What does prevalence equal?
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Incidence * Duration
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Does prolongation of the life of patients with a disease increase or decrease its prevalence?
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Increases it if there is no cure
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What type of rates are used to estimate the burden of disease and to plan health services?
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Crude rates
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What type of rate compares rates among subpopulations without giving a summary figure?
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Specific rates
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What type of rate is used to compare the health of entire populations while controlling confounders and providing a summary figure?
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Adjusted rates
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What represents the risk of dying during a defined period of time for those who have a particular disease?
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Case-Fatality Rate
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What rate is used to estimate the health of populations?
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Fetal Death Rate
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What rate is used for international comparisons?
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Infant Mortality Rate
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What rate reflects health care access and SES factors?
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Maternal Mortality Rate
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T/F With descriptive studies you cannot determine the "who" of the disease but you can determine the what, where, when, and how.
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F - cannot determine the how (cause) of the disease but can determine the rest
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What type of study design has the highest validity?
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Experimental studies
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What type of study is used to determine the efficacy of a treatment or intervention (usually compared to the current gold standard)?
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Clinical trials (which are types of intervention studies--> experimental studies --> analytical studies)
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What is the most-frequently used type of analytical study?
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Case-control study
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What type of study is used to study rare diseases for which medical care is sought?
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Case-control studies
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What type of study is used to study rare exposures?
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Cohort studies
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What type of study is odds ratio measured in?
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Case control study
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What type of study is relative risk calculated in?
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Cohort studies
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How do you calculate relative risk?
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(# of exposed with dx/# exposed) / (# unexposed with dx/# unexposed)
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How do you interpret relative risk?
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If RR=1, then the exposure is not a risk factor for the disease
If RR>1, then the exposure increases the risk for getting the disease If RR<1, then the exposure decreases the risk for getting the disease |
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How do ambispective (historical) cohort studies follow the subjects?
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Uses past health as the baseline, follows data up to present, and continues to follow into the future.
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What type of prevention is the best?
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Primary prevention (before the exposure/pathogenesis)
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What do you want to optimize with a fatal disease?
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Specificity
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What do you want to optimize with a preventable disease?
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Sensitivity
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If penalty of missing a diagnosis is high (e.g. child abuse and sending the kid back into the home), what do you want to optimize?
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Sensitivity
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If further testing is expensive and/or dangerous what do you want to optimize?
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Specificity
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What should specificity of a test be in order to be considered useful?
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98%
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What does a high specificity of a test do to its predictive value?
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Increases PV+
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What does a high sensitivity of a test do to its predictive value?
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Increases its PV-
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What are the four types of biases associated with screening tests?
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Lead time bias
Length bias Volunteer bias Overdiagnosis bias |
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What is the difference between a vector and a fomite?
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Vectors are living
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What is the difference between a vehicle and a vector?
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Vectors are living
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What are some examples of vehicles? Of fomites?
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Vehicles - water, food, blood
Fomites - clothing, doorknobs, eating utensils |
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What rate might be used to measure a food-borne outbreak or other outbreak where the occurrence increases greatly over a short period of time and is related to a single exposure?
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Attack rate
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What does the secondary attack rate measure?
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The spread of a disease among contacts with an initial sick person (measures infectivity of a disease and effectiveness of prophylactics)
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How do you calculate the attack rate?
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=# of people infected who had contact with the sick person / # of susceptible contacts
=(total cases - primary cases) / (susceptible persons - primary cases) |
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How do you calculate the case fatality rate?
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=# who died from disease A in that time period / # who had disease A in that same time period
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What is the basic reproductive number (Ro)?
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The expected number of new infectious hosts that one infectious host will produce during their period of infectiousness in a large population that is completely susceptible
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What does Ro=1 tell you?
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The disease will become endemic (it will stick around)
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What does Ro>1 tell you?
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In a susceptible population, an epidemic will occur
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What does Ro<1 tell you?
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The disease will disappear from the population
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How is the basic reproductive number (Ro) calculated?
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Ro= [beta][kappa][D]
beta=transmission probability per contact kappa=number of contacts per unit time D=duration of infectivity |
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What happens to the value of Ro as the disease spreads?
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Gets lower as people develop immunity (assuming that this is possible --- this is not the case with HIV)
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