Glossary


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C

Competent Authority

Competent Authority

Complementary DNA

Complementary DNA

Compound

Two or more elements or molecules which are chemically bound to each other. The term ˜compound™ is often used to refer to a medicine which is being developed.

Computer Tomography

Computer Tomography

Concomitant

Something that exists or occurs at the same time as something else. It can be a natural event, but in medicine is used when referring to:

  • Concomitant medication: two or more medicines are given at the same time when treating diseases, or
  • Concomitant disease: a second disease (or more) is present at the same time as the primary disease (or secondary symptoms occur with a main symptom).

Confidence Interval

A confidence interval is an estimated range of values in which all data (results) are likely to lie. For a given treatment effect measured in a trial on a sample of a population, the confidence interval can be calculated to give a 'best estimate' range of the treatment effect that will be seen in the whole population.

The likelihood that the confidence interval will contain the value is called the confidence level. Traditionally, confidence levels are set at 95% or 99%. This means that researchers are 95% (or 99%) certain that the measured effect lies within the true range.

For example, instead of estimating the mean age of a population as 15 years, researchers say that the mean age is between 14 and 16. This confidence interval contains the true value being estimated.

Confirmatory studies

These are studies conducted in Phase III of the clinical development of a medicine. They aim to confirm the efficacy and safety in a large patient population. They can involve thousands of patients, can be run in many countries, require a huge amount of expertise to be run effectively, and are therefore resource intense and very time consuming. They are the largest, most complicated, and most expensive part of the development of a medicine.

Confounding Variable

A confounding variable is something, other than the treatment being studied, that can affect the measured outcome of a trial . For example, imagine that a medicine to prevent the common cold is tested by administering it to 1,000 men, while a placebo is administered to a group of 1,000 women. The trial results show that far fewer men caught a cold during the trial period. It would not, however, be possible to conclude that the medicine had an effect because all of the placebo group were women, and therefore gender is a confounding factor. The trial results could have a plausible alternative explanation - for example, that women are more susceptible to the cold viruses circulating at the time of the study.

Well-designed trials take account of potential confounding variables and allow the elimination of plausible alternative explanations for study findings. In the example given above, men and women could be randomly assigned to the intervention and placebo groups to remove gender as a confounding variable.

Continuous endpoint

A measurement, often expressed in numbers, collected in a clinical trial that represents a specific variable. Unlike binary endpoints which are expressed by ˜yes™ or ˜no™ (e.g. ˜survived™ against ˜dead™), continuous endpoints are expressed by measurement on a continuum of possible values over time (e.g. blood pressure or months of survival).

Contract research organisation

A contract research organisation (CRO) is an independent organisation that provides support into the medicines development process. Typically, a CRO will organise and conduct clinical trials to test an investigational medicinal product in humans.


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