Glossary of Terms

Every effort to avoid jargon is made by the professionals involved in clinical trials, however some technical terms are inevitably necessary. Here are some of the most widely used:

Adverse events
This is how the doctor or nurse may refer to side-effects.  They will record every side-effect you have, even if they do not think they are related to the medicine at the time.

Controlled
This means the new medicine is being compared to something else, for example, compared to another medicine or a placebo.

Double-blind
This means that neither the patient nor the doctor know which treatment the patient is taking. (However, the doctor can find out in an emergency if required.)  A special code is used on the medicine and only at the end of the study will this code be broken to show which patients took which treatment. This prevents the patient or, doctor from accidentally taking the treatment into account when reporting benefits or side-effects.

Open-label
This means that both the patient and doctor know which treatment the patient is taking.

Placebo
This is an inactive or ‘dummy’ treatment that may be made of, for example, sugar or chalk.  It looks exactly like the active medicine being tested but does not contain any of it.  Patients may sometimes show a response to placebo but this is because they believe that they may be taking an active treatment and are hoping and expecting it to work (this is called the ‘placebo effect’).  Some clinical trials use a placebo ‘arm’ to test whether the response to the new medicine is real or not.

Protocol
This is a document that is used by the doctor or nurse.  It includes information on the new medicine, why the trial is being done, the procedures and tests to be performed, how long the trial will last, how many trips to the clinic are involved, and how the results will be analysed.

Quality of life
This is often a questionnaire that asks you about how the medicine is affecting you in your everyday life and activities.

Randomisation
Clinical trials often split patients into groups (also called ‘arms’) so that different treatments can be compared.  Patients do not have a choice about which treatment they receive (neither do the doctor or nurse).  The choice is made randomly by a computer program - like the toss of a coin - so that one treatment is not accidentally favoured above another.  The process of being allocated to one group or another is called ‘randomisation’.

Single- blind
This usually means that the patient does not know which treatment they are taking, but the doctor does. This prevents the patient accidentally taking their treatment into account when reporting benefits or side-effects.