Prognosis

Abstract

Determining the prognosis of a disease involves a prediction of the probable outcome. The term natural history is sometimes used synonymously with prognosis, but it is probably better used to describe a particular sort of prognosis—that which ensues in the absence of any therapeutic intervention. The most reliable information about the outcome of a disease is usually derived from the experience of other patients with the same disorder. To estimate prognosis, therefore, we typically examine the outcome of a group of patients who all have the same disorder. To refine our estimate of the prognosis, we compare outcome among subgroups of patients based, for example, on age, gender, comorbidity, or some other variable. Variables or factors that really do predict outcome are known as prognostic factors. Prognostic factors are really just examples of risk factors. In the same way that risk factors predict the occurrence of disease, prognostic factors predict the outcome of disease.