Public Health Flashcards
Relative Risk (RR)
An estimate of the magnitude of an association between exposure and outcome.
Likelihood of developing outcome for the exposed relative to the unexposed.
Absolute Risk Reduction (ARR)
DIFFERENCE in incidence of outcome between exposed and unexposed.
Number Needed to Treat (NNT)
Number of patients needed to be treated in order to prevent ONE adverse outcome (incidence)
Efficacy
Combination of RR and ARR. How much of the risk in placebo (exposed) group is reduced by the new treatment (unexposed)?
How does RR measure the strength of an association?
The RR tells us how much more/less likely two variables are related. (Strength of etiologic association)
How does ARR measure the strength of an association?
ARR will evaluate the actual impact of applying one variable to the other. (ie. treatment group had 2% less bad outcomes than placebo)
Population Attributable Risk (PAR)
Indicates proportion of the risk in the GENERAL POPULATION that would be removed if exposure was eliminated.
This is “efficacy.”
Which is most important to public health?: RR, ARR, or PAR?
PAR- Population attributable risk
Association
Statistical dependence between 2 variables. Does not show causality.
Type 1 Error (alpha)
False Positive. We note they are different when they aren’t.
Type 2 Error (beta)
False negative. We note they aren’t different when they are.
Hypothesis Testing Steps (3)
- Define null hypothesis
- Calculate probability of observed data if null were true (ie. “tinker plot”)
- Look at p-value
Standard Error (SE) vs Standard Deviation (SD)
SE is this standard distribution of a sampling distribution. Standard deviation is the standard deviation of a set of data from 1 sample.
Confidence Interval
Estimated range of values likely to include an unknown population parameter.
Values calculated from sample data.
Statistical Power
The probability of correctly concluding that there is a difference. (1-beta)
What are the 3 forms of community?
- Proximity
- Identity
- Purpose
Communities of Proximity
Things that are close together have similar interests and concerns. (This is easy to do, but you make a lot assumptions-bad)
Communities of Identity
Comprise communities of who you are/identify with; can be very intimate. (Very hard to define)
Communities of Purpose
A group working toward a goal. Clear organizational structure., but limited resources.
Cultural Competence
A set of congruent behaviors, attitudes, and policies that come together in a system, agency, or among professionals that enables effective work in cross-cultural situations
Clinical Diagnosis
Identifying diseased/non-diseased people among patients WITH SYMPTOMS
Screening
The examination of a group of usually asymptomatic individuals to detect those with a high change of having or developing the disease. (ie. physical exam, questionnaire, fluid assays-ie. blood, urine)
Validity
Probability that a test correctly identifies those with and without disease. (lacks bias)
Reliability
Test reproducibility: When the test is repeated, you can expect the same result. (lacks random error)
Two measures of Validity
- Sensitivity (Probability of obtaining true positive)
2. Specificity (Probability of obtaining true negative)
The “Gold Standard”
External source of “truth” regarding disease status of each individual in a population. (This test is very hard to perform)
Positive Predictive Value
Proportion of people with disease among those who test positive. Probability that patient truly has disease.
Negative Predictive Value
Proportion of people without disease among those who test negative. Probability that patient truly doesn’t have disease.
Likelihood Ratio (LR)
How many times more likely is a positive test result is to be found in diseased individuals, compared to non-diseased individuals.
Lead Time Bias
The appearance that early diagnosis of disease will prolong survival with that disease.
Likelihood Ratio Equation
(sensitivity) / (1-specificity)
Positive Predictive Value Equation
PPV= (# correctly screened positive) / (total # screened positive)
Negative Predictive Value Equation
NPV= (# correctly screened negative) / (total # screened negative)
Sensitivity Equation
(# Correct Positives) / (Actual # positive)
Specificity Equation
(# Correct Negatives) / (Actual # Negative)
Definitions of Public Health (3)
- 1988 Fulfilling society’s interest in assuring conditions in which people can be healthy.
- Successive re-defining of the unacceptable (1958)
- Turnock: “It depends..”
Lenses to view public health (4)
- Government View
- Market justice view
- Social justice view
- Political View
Explain the “Epidemiologic Triad?”
The idea that diseases have multiple causes. (Environment Agent Host [Vector])
Why weren’t Koch’s postulates enough to explain disease?
It was not as simple as “bacteria being present to cause disease”
Define Evidence-Based Medicine
Conscientious, explicit, and judicious use of current best evidence in medical decision-making
Hierarchy of Evidence (Most Valid at the top)
(most valid) 1. Systematic Review 2. Randomized Control Trial (RCT) 3. Cohort Study 4. Case-Control Study 5. Physiologic Study 6.Unsystematic Clinical Observation (most bias)
EBM Process (5 A’s)
- Assess (knowledge gaps)
- Ask (an answerable question;PICO patient intervention comparison outcomes)
- Acquire (find evidence)
- Appraise (determine evidence quality)
- Apply (evidence to patient)
Analytic vs Descriptive Epidemiology
Determinants of health and disease vs Distribution of health and disease
4 Reasons to Break Confidentiality
- High Probability
- Serious Injury
- Intervention
- Last Resort
