E9 Statistical Principles Flashcards
double blind
both experimenter and subjects are blinded
crossover study
Each study participant receives all treatments that are being investigated but at different times
Order of treatments is randomized
Washout often included between treatments
Pros of Crossover Study Design
Each patient serves as their own control.
Reduces between-subject variability.
Allows for detection of smaller effect sizes with reduced sample sizes.
Effect Size
Quantitative measure of the magnitude of a phenomenon (eg. the correlation between 2 variables).
Small effect size is one in which there is a real effect, i.e. something is really happening in the world - but which you can only see through careful study.
Parallel Study
Two groups of treatments: A & B
One group receives only A, other group receives only B
most common clinical trial design for confirmatory trials
Longitudinal Study
Repeated observations of the same variables over short or long periods of time.
Often observational but can be structured as longitudinal randomized experiments.
Large Effect Size
Can be seen by the naked eye, easily observed.
Small Effect Size
There is a real effect, i.e. something is really happening in the world - but which you can only see through careful study.
Confounders
Variable that influences both dependent and independent variables so that the results do not reflect the actual relationship
Why is the influence of confounders reduced in crossover studies?
Each patient is their own control.
Optimal crossover designs require ________ subjects.
fewer
Which patient population best aligns with crossover study design?
patients with chronic conditions.
May be infeasible or unethical for curative treatments or rapidly changing conditions.
What are two main issues with crossover studies?
- “Order” Effects. Order of treatment may effect outcome, eg. drug with many adverse effects given first, making patients taking a 2nd, less harmful medication, more sensitive to any adverse effects.
- “Carry-over”. Carry-over between treatments which confounds estimates of treatment effects. In practice “carry-over” effects can be avoided with a sufficiently long “wash-out” period between treatments. However, planning for sufficently long wash-out periods requires expert knowledge of the dynamics of the treatment, which is often unknown.
A trial with the primary objective of showing that the response to the investigational product is not clinically inferior to a comparative agent (active or placebo)
Non - inferiority trial
Trial where the treatment assignment is not known by the study participant - The investigator and staff are aware of the treatment but the subject is not
Single Blind study
The formal evaluation of the quantitative evidence from two or more trials bearing on the same question
Meta-analysis
Comparator (product)
An investigational or marketed product (i.e. active control) or placebo, used as reference in a clinical trial
Non-inferiority Trial
A trial with the primary objective of showing that the response to the investigational product is not clinically inferior to a comparative agent (active or placebo)
A variable that provides an indirect measurement of effect in situations where direct measurement of clinical effect is not feasible or practical
surrogate variable
Therapeutic Confirmatory Study
Phase III
-demonstrate or confirm efficacy/benefit** (the ability to produce a desired or intended result).
-confirm earlier clinical studies that drug is safe and effective to use. - -Provide bases of marketing approval
Phase I (Human Pharmacology Study)
-initial admin of IP to humans.
-Conducted in healthy volunteers or selected population of patients who have disease.
-Tests IP safety, tolerability, pharmacokinetics (what body does to drug), pharmacodynamics (what drug does to body)
investigational product
a pharmaceutical form of an active ingredient or placebo being tested or used as a reference in a clinical trial, including a product with a marketing authorization when used or assembled in a way different from the approved form, or when used for an unapproved indication, or when used to gain further information about an approved use
Exploratory Trial
-What Phase?
-Breifly describe
- Phase II
-Explore therapeutic efficacy - safety and efficacy of drug in selected population
Audit Trial
Documentation that allows reconstruction of the course of events
Pharmacokinetics study
- PK
- The study of how the body affects a drug after administration.
A trial with the primary objective of showing that the response to the investigational product is superior to a comparative agent (active or placebo)
Superiority Trial
composite variable
when a single primary variable can’t be selected from multiple measurements associated with primary variable. A useful strategy is to combine the multiple measurements into a single variable
Full analysis set
the set of subjects that is as close as possible to the ideal implied by the intention-to treat principle
Primary Variable
Capable of providing the most clinically relevant and convincing evidence related to primary objective of trial
Double dummy
Double dummy is a technique for retaining the blind when administering supplies in a clinical trial, when the two treatments cannot be made identical. Supplies are prepared for Treatment A (active and indistinguishable placebo) and for Treatment B (active and indistinguishable placebo). Subjects then take 2 sets of treatment: either A (active) and B (placebo) or A (placebo) and B (active)
biomedical studies not performed on human subjects
nonclincal studies
Equivalence trial
A trial where the primary objective of showing the response to 2 or more treatment differs by an amount which is NOT clinically important
content validity
Assesses whether a test/trial is representative of all aspects of the construct/ domain.
how study population changes in different phases of research
-In earlier phases of drug development the choice of subjects may be heavily influenced by the wish to maximize the chance of observing specific clinical effects of interest,
A. Study population may be very narrow.
-By the time the confirmatory trials are undertaken, the subjects should more closely mirror the target population.
B. helpful to relax the inclusion and exclusion criteria as much as possible within the target population, while maintaining sufficient homogeneity to permit precise estimation of treatment effects