An endpoint is a measurable outcome which can be used in the evaluation of a clinical trial. It is determined before the trial begins and is used in statistical analysis of overall response during the trial to develop a meaningful assessment of whether a device or treatment provides clinical benefits. Determining endpoints can be complex, as a number of measures can be used and many have strengths and weaknesses that can complicate their use in medical studies. In write-ups of studies, researchers will definite and discuss the targets for the benefit of readers.
Two common examples of things that can be used as a clinical endpoint include changes in clinical status or the risk of a major event. For example, if a drug trial is testing a cancer drug, tumor progression is a change in clinical status; the patient’s tumor is getting worse despite the therapy. Likewise, for patients in a trial to evaluate a medication used to prevent stroke, the incidence of stroke could be a clinical endpoint.
When patients reach the clinical endpoint, the details are noted and recorded in the trial data. In reporting, researchers can discuss outcomes and what they mean. They may find, for instance, that an anti-stroke drug actually appears to increase the risk of stroke, by comparing the clinical endpoint statistics between experimental and control groups. Researchers also need to account for people who may have been withdrawn from the study for a variety of reasons.
Participants in clinical trials may need to prepare for repeated visits to monitor their response and take samples for the purpose of assessing response. Blood and urine samples can provide information about the patient’s condition, as can interviews to discuss symptoms and side effects. To maintain the integrity of the study, patients and clinicians may not be informed about who is receiving a placebo, with the goal of preventing the placebo effect and making sure everyone in the study is treated equally.
In some cases, a clinical trial may clearly demonstrate that a device or treatment is not successful and it could endanger patients. Rather than proceeding for the length of the trial or until all participants reach the clinical endpoint, the researchers may decide to halt the study. They can discuss what happened and why to determine if a new study might work more effectively, or if the treatment under investigation is not viable and should be discarded.
