Lecture 4 Flashcards
Sensitivity
The ability of a test to identify who has the disease
TP / (TP + FN)
100% - % sensitivity = % false negative
Specificity
The ability of a test to identify those who do NOT have the disease
TN / (TN + FP)
100% - % specificity = % false positive
Morbidity
rate of disease in a population
Can be described using:
- cumulative incidence proportion
- incidence rate
- prevalence
- attack rate
Cumulative incidence proportion
Period of time during which all individuals in a population are considered to be at risk for the outcome
measure of risk
Incidence Rate
number of NEW cases of a disease that occur during a specified period of time in a population at risk for developing the disease
measure of morbidity
Prevalence
Number of affected persons present in the population at a specific time divided by the number of persons in the population at that time
measure of morbidity
Attack Rate
the number of people that are exposed to something and get the associated outcome, divided by the total number of people exposed
Measure of morbidity
Mortality Rate
number of deaths from a cause in a certain population over a specific period of time
Standardization
set of techniques used to remove the effects of differences when comparing two or more populations
Direct standardization example
rate of disease/death that would have been observed in the study population if it had the same age distribution as the standard population
Indirect standardization example
compares the rate of death/disease observed in the study population to the expected rate from the standard population
Risk Ratio (Relative risk, RR)
ratio of the risk of disease in exposed individuals to the risk of disease in unexposed individuals
RR interpretation
= 1 : risk in exposed group is equivalent to risk in unexposed group
< 1 : risk in exposed group is less than risk in unexposed group
> 1 : risk in exposed group is greater than risk in unexposed group
Odds Ratios (OR)
the ratio of the probability of occurrence of an event to that of non-occurrence
OR interpretation
=1 : no association
<1 : negative association, exposure decreases odds of disease
> 1 : positive association. exposure increases odds of disease
RR vs OR: study utilization
RR: prospective or cohort
OR: retrospective, case-control, multiple logistic regression
Attributable Risk
the amount or proportion of disease incidence or risk that can be attributed to a specific exposure
if the exposure were removed, how much of the disease burden will be reduced
Population Attributable Risk
The attributable risk of an entire population whether or not all in the population have direct exposure
What would be the impact of removing an exposure on the total population?
Hazard Ratio (HR)
rate at which an unfavorable evet occurs; commonly used in survival analysis
HR interpretation
=1 : No association
<1 : Negative association, exposure decreases event rate
> 1 : Positive association, exposure increases event rate
Confidence intervals
numerical range used to describe how reliably study results reflect the entire population
- confidence level reported ahead of the range indicates the probability that the range is accurate
wide range = low precision
narrow range = high precision
if the range includes 0 -> not statistically significant
Number Needed to Treat (NNT)
Number of patients who would have to receive a treatment for one of them to benefit
Number Needed to Harm
Number of patients who receive a treatment before 1 ADE occurs
