Clinical Trials Phase 3 Trials

If the results of clinical trial phase 2 show that a new drug or medical device is effective in at least some of the participants, and nothing indicates that the new treatment poses serious health risks, a clinical trial can advance to phase 3.

Phase 3 trials are large-scale studies that can include several thousand human volunteers and last for multiple years. With this huge amount of data, researchers can use sophisticated statistical analysis to determine a treatment’s efficacy and its safe use in patients.

Primary Purposes of a Phase 3 Trial

Like phase 2, one of the primary aims of clinical trial phase 3 is to measure the efficacy of the treatment in question. Data from phase 2 provide the initial assessment of the treatment’s efficacy, while phase 3 studies aim to determine the actual degree of its efficacy.

Specifically, phase 3 trials examine how many patients respond positively to the treatment and to what extent their condition is improved. Researchers may try to identify any factors that influence the likelihood that a patient will respond positively or negatively to the treatment (e.g. age, sex and other pre-existing health conditions that may be present).

To test its efficacy, phase 3 trials often compare the new drug or device to existing treatments used most commonly in practice. If the tested treatment performs better than the existing treatment in at least some portion of patients, or has fewer side effects than the existing treatment, the new treatment is more likely to be approved for commercial use.

Phase 3 Safety Data

For new treatments that have some level of health risks, researchers may use data from a phase 3 trial to create guidelines on when the benefits of the treatment are likely to outweigh its risks. The aim is to ensure that once the treatment is approved, physicians and other providers will be able to determine when a patient’s condition is serious enough to warrant the potential risks associated with the treatment.


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