As we discuss regularly in this category, pharmaceutical development is a complex process. At the heart of pharmaceutical development are clinical trials, and as we touched on with our post on P-values, understanding the terminology used in clinical trials is key to comprehending what the results mean, and what exactly is going on.
Clinical trial terminology can be quite confusing and impenetrable, but understanding the trials structure and methods used through a clear understanding of the terminology can provide a fascinating insight into what data is being gathered, how and why.
Below are some commonly used words and their definitions. If you have any that you would like us to explain, please leave a comment and we’ll update the post with definitions and discussion.
Placebo – “a substance or procedure … that is objectively without specific activity for the condition being treated” Within the context of clinical trials, the administration of a placebo is used to create data that measures symptoms, etc, when there is no therapeutic substance present. Using placebos in clinical trials makes allowance for the ‘placebo effect’.
Placebo effect – it is a common and reported occurrence that some patients experience, report and exhibit results and effects when administered an inert or ineffective treatment, a placebo.
Randomised / randomisation – procedure by which trial participants are randomly assigned to the various groups of patients in a clinical trial (control, placebo, active). Randomly allocating the group members in this way aims to ensure that there is no bias to the groups in relation to age, sex, etc.
Open label trial / open trial – both researcher and patient know the full details of the treatment being administered.
Single blind trial – only the researcher knows whether the patient is receiving an active treatment or placebo.
Double blind trial – neither the researcher nor the patient know whether the drug being administered is active or a placebo.
Significance / statistical significance – this refers to the strength of data generated by a clinical trial to support a particular finding or conclusion. It can refer to the likelihood of the same effects or results being observed randomly, ie, in comparison to a placebo or control group.
Adverse event / side effect – Any undesired actions or effects of a drug or treatment.
Crossover study – a crossover study is where at a point in the trial the placebo and active groups switch, so formerly placebo patients are given active drug, and vice versa.
Anecdotal – means unreliable in reference to evidence. It may be true, but is not verifiable/verified or there is doubt about its veracity and trustworthiness.
Endpoint – these are the overall outcomes that the trial protocol is designed to evaluate. Common endpoints are survival, improved quality of life, relief of symptoms, disappearance (curing) of condition.
Pharmacokinetic – what a living body does to a drug or introduced chemical/substance, eg. How does the body absorb, metabolise, distribute and/or excrete the substance?
Pharmacodynamic – what a drug or introduced chemical/substance does to a living body, eg. How and what does the drug depress, stimulate, destroy (cells), irritate or replace?
Efficacy – refers to the ability, or otherwise, of a drug or treatment to deliver a desired beneficial effect.
Interim results / analysis – these results refer to a segment of full trial results. They may be the full trial results from a segment of trial participants (ie, one trial site or location) or results for all participants, but from one segment of time (ie. Four months of full data from a 12 month trial).
***UPDATE***
Cohort – a group of individuals who share common characteristics or experiences, or have shared a common experience within a particular time. The use of cohorts in clinical trials seeks to remove or minimise unforeseen or un-measurable impact from lifestyle, demographic or generational variables by ensuring that trial participants are as similar to each other as possible.
Prospective – means ‘looking forward’. Participants are located and then followed over time. It implies that the protocol for gathering and examining data has been set prior to the trial commencing, as opposed to studies that review existing data with a view to discovering or proving new findings and relationships.
Multicentre – refers to a clinical trial that is run out of several geographically separate locations (sites, such as hospitals or medical centres). This may be intentional, to study the difference that geography, race, etc, may have on a treatment or condition, or in the case of rare diseases, be necessary to maximise the number of trial participants.
Single site – refers to a clinical trial that is run out of one location (site) only.
Non-interventional – also referred to as observational, these trials must take place without interference or control from researchers, trials are not subject to design and protocol, but reflect the ‘real-world’ use of an already approved treatment.
Uncontrolled – a trial that does not contain a control group, ie, a group of ‘cohorts’ who are not on active treatment or who are on a placebo treatment.
This is far from an exhaustive list of clinical trial terminology. If you come across any terms that you are unfamiliar with, or would like us to include, please leave a comment below.
References:
http://www.annals.org/content/136/6/471.full
http://www.ncbi.nlm.nih.gov/pubmed/6369471?dopt=Abstract
Image reference:
Thanks for the list.
How about terms like prospective cohort/cohort, multi-center trial and non-interventional study ?
Might be nice to mention them too.
cheers,
davidp.
Thanks Davidp! We’re working on those additions now.
Here is a study description I read just today
“uncontrolled, observational, prospective, open-label, single site”