3/21 BS Flashcards
Case control study
- prospective or retrospective?
- odds ratio or relative risk?
- retrospective
- odds ratio
Clinical trial: Phase 1
- who are the subjects?
- what are you testing?
- Small number of healthy volunteers.
- “Is it safe?” Assesses safety, toxicity, and pharmacokinetics.
Clinical trial: Phase 2
- who are the subjects?
- what are you testing?
- Small number of patients with disease of interest.
- “Does it work?” Assesses treatment efficacy, optimal dosing, and adverse effects.
Clinical trial: Phase 3
- who are the subjects?
- what are you testing?
- Large number of patients randomly assigned either to the treatment under investigation or to the best available treatment (or placebo).
- “Is it as good or better?” Compares the new treatment to the current standard of care.
Clinical trial: Phase 4
- who are the subjects?
- what are you testing?
-Postmarketing surveillance trial of patients after
approval.
-“Can it stay?” Detects rare or long-term adverse effects. Can result in a drug being withdrawn from market.
Vaccine
-whats reduced, incidence or prevalence?
Both
Precision
- aka?
- define
- relationship to standard deviation?
- Reliability
- The consistency and reproducibility of a test.
- More precise a test, the smaller the standard deviation.
Accuracy
- aka?
- define
- Validity
- The trueness of test measurements. The absence of systematic error or bias in a test.
Internal validity:
How well the conclusion corresponds to the real situation in the sample population.
Berkson bias
- what type of bias?
- what is it?
- Selection & sampling bias.
- A study looking only at inpatients.
Hawthorne effect
- what type of bias?
- what is it?
- Measurement bias
- Groups who know they’re being studied behave differently than they would otherwise.
Pygmalion effect
-aka?
-Observer-expectancy bias
Lead-time bias
-what is it?
Early detection confused w/inc. survival.
-seen w/improved screening techniques.
Lead-time bias
-how do you reduce this bias?
Measure “back-end” survival (adjust survival according to
the severity of disease at the time of diagnosis).
Crossover studies
-what is it?
-subjects act as their own controls.
Matching
-what is it?
- patients with similar characteristics in both treatment and control groups.
- the matching variables should be the confounders of that study.
- a way to reduce confounding bias.
standard error of mean (SEM)
-relationship w/sample size
As (n) increases, SEM decreases.
Skew:
-define it
Think of normal bell curve but you grab one side and pull
it a little. If you pull it to the right, its positive skew. And
in ABC order, you drag the Mean, Median, and Mode along with it.
Power of a study
- equation:
- what is it?
- aka?
- (1 – β)
- ability to detect a difference btwn groups when a difference truly exists.
- like “true positive”.
Chi-square (χ²)
- what is it?
- mnemonic?
- Checks difference between 2 or more percentages or proportions of categorical outcomes (not mean values).
- “Pronounce Chi-tegorical”
-Example: comparing the percentage of members of 3 different ethnic groups who have essential hypertension.
Coefficient of determination =
- r^2 (value that is usually reported).
- r = Pearson correlation coefficient
Disease prevention
-mnemonic?
PST:
- Prevent
- Screen
- Treat
Disease prevention: primary
-Prevent disease occurrence (e.g., HPV vaccination).
Disease prevention: tertiary
-Treatment to reduce disability from disease (e.g., chemotherapy).
Disease prevention: Quaternary
-Identifying patients at risk of unnecessary treatment, protecting from the harm of new interventions.
Informed consent requires what 4 things?
- Disclosure
- Understanding
- Mental capacity
- Voluntariness
Therapeutic privilege
-what is it?
-withholding information when disclosure would severely
harm the patient or undermine informed decision-making capacity.
Situations in which parental consent is usually not required for minors:
- Sex (contraception, STDs, pregnancy)
- Drugs (addiction)
- Rock and roll (emergency/trauma)
*they can get prenatal care BUT 2/3 of the states require parental consent for abortions.
Medical power of attorney
-Can a pt revoke it even if hes not competent?
-Yes. Can be revoked anytime patient wishes (regardless of competence).
Surrogate decision maker
-order:
Spouse, adult children, parents, adult siblings, other relatives.
Reportable diseases
-examples:
-STDs, TB, hepatitis, food poisoning.