For example, suppose that a medical trial compares four treatments.

Each month, the independent scientists reviewed data from the trial comparing the effects of the two treatments.

The results of the second trial comparing the drugs, known as Isis-3, were announced this March.

Clinical trials may also compare a new treatment to a treatment that is already available.

The typical clinical trial compares two groups of patients.

A clinical trial comparing different chemotherapyregimens (doses and schedules of treatment).

"There still is no gold standard randomized trial comparing embolization to the other interventions," he added.

The Vioxx findings were based on the strongest evidence - a clinical trial comparing the drug with a placebo.

A controlled trial comparing 12 to 24 weeks of treatment failed to show any beneficial effect of the prolonged therapy.

A clinical trial to compare high-dose and low-dose radiation therapy.