Design of Randomized Controlled Trials in the Treatment of Leg Ulcers: More Answers with Fewer Patients

Abstract

Objective:

To illustrate the benefit of the factorial design in randomized controlled trials of leg ulcers.

Design:

A 2 × 2 × 2 factorial design.

Setting:

Hospital leg ulcer clinics in Edinburgh and Falkirk.

Patients:

Adults with at least one unhealed leg ulcer of determined origin, present for at least 2 months and greater than 1 cm in diameter.

Interventions:

Pentoxifylline (Trental) 400 mg, three times daily, versus placebo

Main outcome measure:

Complete healing of all ulcers within 24 weeks.

Results:

Of 525 patients screened, 200 pure venous ulcers were randomized (58.5% healed by 24 weeks), 45 complex venous ulcers were randomized (57.8% healed) and 41 arterial patients were randomized (excluding bandaging comparisons) (19.5% healed). There were no interactions between treatments.

Conclusion:

The factorial design was feasible to administer and allowed three therapeutic questions to be investigated using the same resources as would have been needed to answer a single question.