لخّصلي

Classical clinical trial design is rigidly structured to investigate a set number of variables and prevent additional variables from being introduced that will confound the results.The benefit of these strict criteria is a well-defined population to be studied that excludes patients predicted to be potentially harmed if entered into the trial.For instance, a traditional, randomized, controlled trial stipulates inclusion and exclusion criteria to allow only a specific population of patients entering into the trial.

Classical clinical trial design is rigidly structured to investigate a set number of variables and prevent additional variables from being introduced that will confound the results.
For instance, a traditional, randomized, controlled trial stipulates inclusion and exclusion criteria to allow only a specific population of patients entering into the trial.
The benefit of these strict criteria is a well­defined population to be studied that excludes patients predicted to be potentially harmed if entered into the trial.
However, the disadvantage of such rigidity is the inability to make adjustments to the inclusion and exclusion criteria as the study progresses and new information comes from those patients who have completed the trial.
If the investigators discover there is a specific patient group that responds to the treatment during the trial, adjustments to include only that patient population are not allowed.
For that reason, a significant number of patients who are anticipated to not respond are exposed to a treatment that may cause severe side effects.