The problem of identification of prognostic factors for persistent trophoblastic disease.

The role of anamnestic and clinical factors in defining the high group at risk of developing persistent trophoblastic disease (PTD) has been analyzed in 301 cases of hydatidiform mole. Patients age 40 or more years with AB blood, and a previous history of molar pregnancy had an elevated risk of developing PTD. The presence of various risk factors increased the frequency of PTD. However, with discriminant analysis, correct classification of outcome was obtained for only 69% of cases. Despite the magnitude of risk of PTD for women with three or more risk factors, the clinical relevance of prognostic variables in the prediction of outcome was limited by the low proportion of women classified in the low- and high-risk groups, making the identification at diagnosis of the women who could benefit of prophylactic chemotherapy extremely difficult and hence of little clinical importance.