Dr Jeremy Howick, Centre for Evidence-Based Medicine, University of Oxford

Abstract: A resilient issue in research ethics is whether and when a placebo-controlled trial (PCT) is justified if it deprives research subjects of a recognized treatment. The clinicians' moral duty to provide the best available care seems to require the use of 'active' controlled trials (ACTs) that use an established treatment as a control whenever there is an established therapy. On the other hand, ACTs are supposedly methodologically inferior to PCTs. Hence, the moral duty of the clinical researcher to use the best methods will favour PCTs. In this paper I analyze the three reasons for believing that ACTs are inferior to PCTs namely: (1) ACTs lack 'assay sensitivity' (2) ACTs do not measure absolute effect size (3) ACTs require more participants and contend that none are acceptable. Consequently the tension between clinical and research ethics dissolves: the moral duty of the clinician to avoid PCTs is unopposed by methodological considerations.