predictive power of human chorionic gonadotropin in post-molar gestational trophoblastic neoplasia: a longitudinal roc analysis

Background: the present study aims at identifying an applicable longitudinal marker from the serum human chorionic gonadotropin (hcg) levels during 3 weeks after mole evacuation for predicting the gestational trophoblastic neoplasia (gtn) in patients with partial or complete molar pregnancy. methods: in this historical cohort study, 201 documents of patients with hydatidiform mole (according to their pathological reports) were investigated. a two-stage shared random effects model was used to describe the relationship between repeated measures of β-hcg (as a longitudinal indicator) and incidence of gtn. a receiver operating characteristic (roc) curve was used to determine the power of repeated β-hcg values for predicting gtn. results: among all patients, 171 cases (85.1%) had spontaneous remission and gtn was detected in 30 cases (14.9%). the modeling approach used in the current study revealed that the repeated measures of β-hcg concentration (in weeks 0, 1, 2, and 3) can correctly classify approximately 86.7% of patients with gtn and 83.0% of patients without gtn. the repeated measures of -hcg concentration had higher predictive accuracy than cross sectional values of this marker for early detection of gtn. conclusions: in general, findings of the present study showed that the three-week β-hcg concentration is a powerful marker for predicting gtn in women with molar pregnancy (with auc of 91.2%). thus, monitoring the three-week trend of this marker is recommended for early detection of this malignancy in these women.