What are clinical trials?
controlled human studies to access dosage, administration, safety, efficacy
What is phase 1 of clinical trials
- small scale, testing for tolerable dosing rages, bioavailability, excretion
What is phase 2 of clinical trials
intermediate scale, testing for efficacy, monitoring for safety in greater number of patients
What is phase 3 of clinical trials
large scale, randomized, double blind trial (both doctor and patient are blind to the treatment), compared against a placebo or current accepted treatment
What is systematic review/meta analysis
approach to combine date from multiple trials, often after a drug has been approved. can increase our confidence of the effectiveness of a drug
What is the odds ratio (OR)
ratio of the event rate in treatment vs control (which one is favoured in individual trials vs overall)
What is the therapeutic index?
- a drug has to have a beneficial effect, but also a tolerable in terms of toxicity
- ratio of median toxic dose and effective dose)
- effect or toxicity is described as a quantal dose response curve
What are some considerations with the therapeutic index
- big therapeutic index is usually good - drug is tolerated with minimal toxicity and gives a lot of flexibility for dosing
- may be a lot of individual variability in drug response
- other conditions (diet, liver + kidney function) might need to considered as they affect sensitivity
- useful in drug development, but should not be used as a rigid criteria for administration in clinical setting
What is relative risk reduction
defined as 1 - (event rate in treatment group)/event rate in control group
What is an event
defined in whatever study you are reading, examples are mortality cases, cardiovascular event
What might relative risk reduction be misleading
- it does not convey the magnitude of the baseline risk, it doesn’t capture the difference between a large reduction in something that is very infrequent, verses something very frequent
What is absolute risk reduction
- more descriptive way to report the benefit of taking a drug
- absolute risk reduction describes the absolute number of cases that are prevented by taking a drug
- absolute risk reduction = event rate in control - event rate in treatment group
What is numbers needed to treat
another way to think about absolute risk
NNT = 1/ARR
What are some things to consider when thinking about numbers needed to treat
- a low NNT is good = everyone taking drug receives benefit
- high NNT is not good = most people will not receive benefit
- we can also consider the number needed to harm, low NNH is bad, high NNH is good
