Endpoint of a clinical trial

The endpoint (the objective criterion) is the measurand defined in the protocol that has the strongest power to answer the key question of a clinical trial. It should be a criterion validated according to scientific standards, by which, for example, the efficacy or tolerability of the drug or medical device is investigated. The primary target criterion corresponds to the main target criterion, while often several secondary target criteria, i.e. secondary criteria, are defined.

There should always be only one target criterion, which should be formulated precisely and carefully. The validity of the endpoint is essential here, so that it must be checked whether the target criterion really captures what is to be investigated in the study. The target criterion must still be reliable, i.e. reproducible.

Possible main criteria can be efficacy and tolerability of the drug or medical device, scales (e.g. visual analogue scales to document the intensity of pain) or clinical criteria (e.g. death or hospitalisation). There are also combined endpoints, so that only one of several defined events must occur for the endpoint to be reached. A combined endpoint can, for example, be heart attack, stroke or death. The advantage of defining a combined endpoint is that more events can be recorded and thus the number of cases required for the study can be reduced.

Often several secondary criteria such as satisfaction, quality of life, improvement in laboratory values, etc. are defined.