The payer and the piper--a view on evidence-based medicine.

Filtration should be carried out within 48 hours of collection, i.e. by the transfusion service. Bedside filters are not recommended since consistent quality control is not possible and older units will accumulate cytokines, etc. which may be responsible for some of the side-effects attributed to white cells. Obviously if individual clinicians believe that their patients would benefit from leucocyte-depleted components for indications other than those above, they should naturally request this and the Services will issue accordingly. By monitoring the usage and gearing up accordingly the Services will be in a position to meet any such demands.