Biased Ascertainment and the Natural History of Diseases

The outcome of a given chronic disease is of much interest to the individual patient and his physicians. Knowledge of the natural history of untreated disease becomes particularly important in decisions regarding initiation of treatment and assessing the effect of various modes of therapy on the course of a given disease. A bias in most published data regarding prognosis and natural history of chronic disease suggests worse outcomes than actually apply. Inappropriate therapeutic decisions may result.Many chronic diseases have a wide range of clinical manifestations. Patients with more severe symptoms are more likely to find their way to physicians. . . .