Michelson et al (Reference Michelson, Allgulander and Dantendorfer2001) evaluated the efficacy of fluoxetine in panic disorder and reported that fluoxetine was associated with a significantly greater proportion of panic-free patients compared with placebo. We read this double-blind randomised study with interest and wish to raise some concerns about the use of a placebo arm.

The use of placebo arms in randomised controlled trials remains a controversial issue and has been criticised on ethical grounds. In this context, the Declaration of Helsinki demands that individual patients in a study ‘be assured of the best proven diagnostic and therapeutic method’ even in the control group (Reference Rothman and MichelsRothman & Michels, 1994). This statement clearly discards the use of a placebo as control when a ‘proven’ treatment exists. The declaration also directs that a study that violates its precepts should not be accepted for publication.

In addition to this, a trial that aims to establish whether a treatment is better than placebo may be trying to answer the wrong question. After all, even if a new treatment is worse than an existing one, it may still be ‘effective’ in that it is better than no treatment (placebo). In this regard, Hill (Reference Hill1963) pointed out that the essential medical question at issue is how the new treatment compares with the old one, not whether the new treatment is better than nothing.

As there are many drugs with proven efficacy in panic disorder (i.e. benzodiazepines, tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, reversible inhibitors of monoamine oxidase A and buspirone), we are keen to know why the authors did not try to compare the efficacy of fluoxetine with existing drugs. It appears that they are keen to reflect a drug-specific effect rather than demonstrating the relative efficacy. In this context Cochrane (Reference Cochrane1989) stated that 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 treatments but cheaper or safer.