Abstract

The medical concept of prognosis is analysed into its basic constituents: patient data, medical intervention, outcome, utilities and probabilities; and sources of utility and probability values are discussed. Prognosis cannot be divorced from contemplated medical action, nor from action to be taken by the patient in response to prognostication. Regrettably, the usual decision-theoretic approach ignores this latter aspect. Elicitation of utilities, decision contemplation and prognostic counselling interweave, diagnostics playing a subsidiary role in decision-oriented clinical practice. At times the doctor has grounds for withholding information. As this is known to the patient, prognostic counselling becomes a conflict-prone and rationality-thwarting activity. The meaning of standard phrases such as prognosis of a disease, the prognosis of this patient, the prognosis is unknown, is examined.