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Types & Phases

Types of clinical trials

The most common type of clinical research tests new drugs and other treatments. Other studies are conducted to find new, improved ways of preventing, detecting and diagnosing specific diseases or conditions. There are also studies to find new ways to improve the quality of life for patients with chronic diseases.

Clinical trial phases

There are four phases of clinical trials. Each phase may take months or even years to complete, so a patient rarely participates in all phases of a clinical trial.

  • Phase I: Assess patient safety
    The first step in testing a new drug or treatment on patients is to determine its safety, dosage and side effects. This phase usually involves small groups of patients.
  • Phase II: Assess treatment effectiveness
    The new drug or treatment is tested on a larger group of patients. Researchers continue to test the safety of the drug or treatment while evaluating its effectiveness.
  • Phase III: Compare new treatments to standard therapies
    Researchers determine if the new treatment is better than, the same as or worse than a commonly used treatment. Some patients receive the new treatment while others receive the commonly used treatment. This phase may involve hundreds or thousands of patients at multiple locations.
  • Phase IV: Long-term safety and effectiveness
    These studies take place once the new treatment is approved for standard use and put on the market. We do not conduct phase IV trials at our hospital.