Predictors of Success of Methotrexate in the Treatment of Ectopic Pregnancy: A New Perspective

Abstract

Objectives: Methotrexate is commonly used in the treatment of ectopic pregnancy. Outcomes with a suboptimal drop in human chorionic gonadotrophic (hCG) level are unknown. This study aimed to determine the optimal cutoff value for hCG drop in detecting treatment success, to investigate the predictors of success, and to evaluate outcome following a single dose of methotrexate as treatment of ectopic pregnancy.
Methods: A retrospective study was conducted of 182 patients with ectopic pregnancy treated with methotrexate. Outcomes included resolution of hCG or further surgical intervention. The optimal cutoff value for hCG drop in prediction of treatment success was evaluated using receiver operating characteristic curve analysis.
Results: The success rate was 79.1%. The cutoff value for hCG drop between day 4 and day 7 for prediction of success following a single dose of methotrexate was 3.34%, with a positive predictive value of 91.67%. Compared with subjects with initial hCG level of <1000 IU/L, there was a significant reduction in success for those with initial hCG levels ranging from 1000 to 3999 IU/L (odds ratio=0.184; p=0.02), 4000 to 4999 IU/L (odds ratio=0.116; p=0.03), and ≥5000 IU/L (odds ratio=0.057; p=0.01).
Conclusions: Pretreatment hCG level and hCG drop between day 4 and day 7 are good predictors of success following methotrexate treatment. With a high positive predictive value for success, conservative management with serial hCG monitoring may be considered when drop in hCG level between day 4 and day 7 is ≥3.34%.