Epidemiology Flashcards
A certain disease has a stable incidence but an increased prevalence over time. What would explain this?
Improved quality of care.
Incidence=measure of new cases.
Prevalence=measure of those with the disease in the population at a specific time.
Thus, if there’s an increasing prevalence, it means the people w/ the disease are being treated in a way that they are living longer (causing the prevalence to increase)
What is the difference between Type 1 and Type 2 error?
How do you calculate statistical power?
Type 1 error (alpha)=reject null hypothesis when its true (ie there is no difference between two treatments but you say there is).
Type 2 error (beta)=Fail to reject null hypothesis when it’s false (ie conclude that there is no difference between treatments when there actually is).
Statistical power=1-beta. It is the probability of rejecting a null hypothesis when it is truly false. Usually set at 80%.
This is more pharmacokinetics but:
What is the equation for half life?
t/12=(0.7*Vd)/CL
where Vd=volume of distribution, and CL=clearance.
What is Berkson’s bias?
Bias that occurs by choosing hospitalized patients as control group
What’s the Hawthorne effect?
When behavior changes because people know they’re being observed.
What’s lead-time bias?
It’s when a disease is apparently prolonged because screening picks up on it sooner, but the prognosis doesn’t change. The screening method just makes it more detectable.
What’s the Pygmalian effect?
It’s when a researcher’s belief in the efficacy of a treatment can potentially affect the outcome (ie teachers who think kids have more IQ put in more time, those kids are more successful).
What’s the formula for loading dose and maintenance dose?
Loading dose=(Plasma Concentration(Cp)Volume of Distribution)/Bioavailability (F)
Maintenance dose=(CpCL*dosing interval)/F
F=100% if IV.
The RR of something is 1.5. CI=(1.2-1.8). What must the p value be?
p=.05 or less
What type of test is used to analyze differences in means between more than 2 independent groups?
Analysis of Variance
T test would be used for 2 groups or less.
Two drugs have equal efficacies, but one is twice as potent as the other. What would that graph look like?
They both would reach the same peak on the y axis. The more potent drug would reach the peak at 1/2 the point of the other drug on the x axis.
Efficacy=action of the drug
Potency=dose required to achieve efficacy.
How long does it take for a drug to reach steady state?
4-5 times its half life. (3.3 half lives to reach 90%)
