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

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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.