Study's design leaves cost effectiveness and 'therapeutic impact' in doubt

EDITOR,--Evaluation of diagnostic technology is generally more difficult than evaluation of therapeutic technology and is often omitted. C M Francis and colleague's study of the use made by general practitioners of an open access echocardiography service is therefore welcome.1 The descriptive design of the study, however, limits the conclusions that may be drawn from the findings. A comparative study (for example, with a randomised design) would …