Klysner et al (Reference Klysner, Bent-Hansen and Hansen2002) evaluated the prophylactic efficacy of citalopram in comparison with placebo in elderly patients, and stated ‘the highly recurrent nature of major depression in the young and the elderly warrants long-term antidepressant treatment’. In view of this, is it ethical to use a placebo arm? The answer to this question depends upon whether or not there is an already available treatment of proven or accepted value. In this context, Cochrane (Reference Cochrane1989) stated that ‘placebo controlled trials are appropriate when there is no existing treatment for a disorder, otherwise comparison trials are indicated. No new treatments should be introduced into medicine unless they have been shown, in randomised controlled trials, to be superior to existing treatments, or equivalent to existing treatment but cheaper or safer’. Similarly, section 12.4 of the National Health and Medical Research Council (1999) statement on ethical conduct in research involving humans states: ‘the use of a placebo alone or the incorporation of a non-treatment control group is ethically unacceptable in a controlled trial where: (a) other available treatment has already been clearly shown to be effective; and (b) there is a risk of significant harm in the absence of treatment. If there is genuine uncertainty about the net clinical benefit of a treatment, a placebo controlled trial or a trial with a no-treatment arm may be considered’.

The use of placebo in this clinical drug trial raises questions of deception, of patient information and of informed consent. The patients in the placebo group were left without any active treatment for 48 weeks — this raises doubt as to whether patients were fully informed, before giving their consent, that they might receive a placebo by random allocation. We are keen to know why the authors did not try to compare the efficacy of citalopram with existing antidepressants.