Sir: I would like to comment on an aspect of Laugharne's analysis of evidence-based medicine (EBM) (Psychiatric Bulletin, November 1999, 23, 641-643). He states that the philosophy underlying EBM consists of rational and measurable interventions that should prove beneficial to patients. This does not do much to resolve the tension between EBM and user involvement. If these principles are not integrated to other basic concepts, then he has outlined the basis of what I call ‘evidence-slaved medicine’.

Sacket et al (Reference Sacket, Rosenberg and Gray1996) define EBM as “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients…”, and”… external clinical evidence can never replace individual clinical expertise and it is this expertise that decides whether the external evidence applies to the individual patient at all, and, if so, how it should be integrated into a clinical decision”.

Laugharne stresses the extent to which medicine must catch up with aspects of non-linear dynamics and quantum mechanics. However, realising the observations made by Poincaré (19th century) and Planck (20th century) might not help him much here. He may find that the observations about games that Bayes made in the 18th century are much more useful.

Laugharne's dilemma may be approached by using concepts of decision analysis, a slowly evolving aspect of EBM. Roughly, a clinical decision process must include the patient's relative preferences (e.g. utilities), or better still, the values that the patient assigns to such utilities. Only when a patient cannot do this, might the clinician alone quantify these utilities. In either case, the final decision may not necessarily favour the option best supported by the external evidence.