Editors are not immune to the dangers of abbreviations. In a letter by Arminée Kazanjian (“Comprehensive evidence is needed in decision making,” 26 May, p 1304) we rather foolishly spelt out the author's abbreviation “CTs” as computed tomography (see beginning and end of third paragraph). In most situations this is indeed the usual meaning, but unfortunately in this case the author was referring to clinical trials. We apologise for this.