Lecture 5- Does the Drug really Work?

Question 1

What are clinical trials?

Answer 1

Controlled human studies to asses dosage, administration, safety, efficacy

Question 2

Which phase of clinical testing does the following describe?
* small scale (dozens of subjects), testing for tolerable dosing rages, bioavailability, excretion

Answer 2

Phase 1

Question 3

Which phase of a clinical trial does the following describe?
* Intermediate scale (hundreds of subjects), testing for efficacy, monitoring for safety in greater numbers of patients)

Answer 3

• phase 2

Question 4

Which phase of a clinical trial does the following describe?
* Large scale, randomized, double-blinded, compared against a placebo or current accepted treatment

Answer 4

phase 3

Question 5

What are systematic reviews, meta analysis?

Answer 5

• an approach to combine data from multiple trials, often after a drug has been approved. This approach can increase confidence in our view of the effectiveness of a drug, and help guide future policy regarding drug use

Question 6

Results of meta-analyses are often displayed as ____ plots

Answer 6

forest plot; a concise summary of huge amounts of clinical data

Question 7

What kind of data do forest plots provide?

Answer 7

• number of trials
• size of each trial
• outcomes of trials
• overall summary of all trials

Question 8

What is OR?

Answer 8

Odds ratio; the ratio of the event rate in treatment vs control

Question 9

What is a theraputic index?

Answer 9

• It is the ratio of the median toxic dose and effective dose; TI = Td50/Ed50
• effect or toxicity if often described using a quantal dose-response
• The bigger the ratio or the bigger the dosing different between the benefical effect curve and the toxic effect curve, the better = good theraputic index meaning you can safely give large doses of the drug without having a risk of a toxic or adverse outcome in the patient.

Question 10

Why is a large theraputic index good?

Answer 10

It means the drug is tolerated with minimal toxicity and gives a lot of flexibility for dosing

Question 11

Relative Risk Reduction

Answer 11

1 - (event rate in treatment group)/(Event rate in control group)
* i.e., Drug Y ia an amazing drug used to treat high blood pressure and prevents heart failure. In a study of Drug Y, 1500 out of 10000 control patients develop high blood pressure. 500 out of 10000 patients on drug Y develop high blood pressure
* RRR = 1-(0.05/0.15) = 66%

Question 12

What is absolule risk reduction?

Answer 12

• describes the absolute number of cases that are prevented by taking a drug
• ARR= event rate in control - event rate in treatment group
• ARI = event rate in treatment - event rate in control
• eg:
  1000 subjects take a placebo and 250 experience >25% hair loss

1000 subjects take Drug X and only 125 experience >25% hair loss

ARR = (250/1000) - (125/1000)

ARR = 12.5%

Question 13

Another useful way to think about absolute risk, or population-level benefit of a drug, is the ____.

Answer 13

NNT- number needed to treat
NNT = 1/ARR

Question 14

Why is a low NNT good?

Answer 14

NNT of 1 means that just everybody taking the drug will receive the desired benefit

Question 15

Why is a high NNT not good?

Answer 15

High NNT means most people will not receive a benefit by taking a drug; it means that a lot of people taking the drug would be exposed to possible harm

Question 16

Low NNH is ____ and high NNH is ____

Answer 16

bad;good