To the editor: Dr de Belder asks the question how to determine the worth of drug-eluting stents?1 The answer to this question does not lie in the trial data. The function of trial data is to establish the extent of clinical-effectiveness to a given degree of certainty. In this context, while a trend may generate a hypothesis it does not establish clinical-effectiveness.

There is no balance between clinical- and cost-effectiveness. Clinical-effectiveness necessarily precedes cost-effectiveness. If there is a balance to be struck it lies between value and cost. The cost is set by the market and by negotiation between the respective parties. Once this is settled the remaining key variable left to be determined is the value placed upon the degree of benefit demonstrated by the clinical trial evidence.

The value of the intervention to the patient as perceived by the NHS has to be balanced against its cost to the NHS as payer. It is this combination of clinical-effectiveness, cost and value2 that presently falls to NICE to consider.

Importantly, note that the value to the patient of the treatment is judged not by the patient but by the payer. Because of this critical point the process should possess a stronger political component than it presently does. This is because it is politicians and not NICE who are directly accountable to the key stakeholders—that is, the public, whose dual guise as patients and tax payers drives this dilemma.3

Questions of clinical-effectiveness can yield to randomised controlled clinical trials. However it is clear, from the principle of fact–value distinction first expressed by David Hume,4 that the value of an intervention cannot be determined from the trial data because trial data only ever return a factual conclusion. Questions of value yield to the principles of ethics. Questions of cost yield to principles of economics.

As the present situation with drug-eluting stents demonstrates there seems to be a need to engage doctors who can wield the full spectrum of such principles with the aim of better protecting the interests of patients.