Analysis of risk factors for persistent gestational trophoblastic disease

Persistent disease is a serious consequence of molar pregnancies. Its early detection is critical to effective chemotherapy. Therefore, determination of risk becomes an important clinical decision.

To determine the relative risk of persistent disease in a cohort of patients with partial and complete molar pregnancies by analysis of five factors derived from a database using multivariate analysis.

Of 686 patients, 78 developed persistent disease which required treatment (rate of 11.3%). Risk was markedly increased when serum human chorionic gonadotrophin (HCG) failed to reach negative by 12 weeks after evacuation [hazard ratio (HR) = 120.78, P < 0.001]. Risk was markedly decreased when the interval from last pregnancy exceeded 12 months (HR = 0.24, P = 0.005). Other factors such as patient's age, stage of gestation and serum HCG level at presentation were not found to be strongly associated with risk of persistent disease.

These findings support the application of the following two factors in risk prediction for molar pregnancies: > 12 weeks to become HCG negative and interval from last pregnancy < 12 months. They will contribute to a greater awareness of persistent disease and assist in early detection and effective chemotherapy.