Pharmacological treatment of ectopic pregnancy: Accuracy, safety and cost-effectiveness of day 1–7 β-hCG measurements

Objective: The aim of the present study was to compare accuracy, safety and cost-effectiveness of three β-hCG measurements protocols, applied in managing ectopic pregnancies (EP) with methotrexate (MTX): (1) day 1 to 7 β-hCG levels, (2) day 1 to 4 β-hCG levels and (3) day 4 to 7 β-hCG levels. Methods: Cost-minimization analysis (CMA) based on a retrospective study of patients treated with single-dose MTX for EP, was evaluated at a single institution between January 2001 to May 2021. Successful MTX treatment was defined as no surgical intervention. We evaluated safety by analyzing cases of day 4 interventions and cases of inconsistency between the different protocols. Predicting accuracy was assessed by the area under the receiver operating characteristic (AUC) curve. Results: A total of 229 patients with single dose MTX treatment were included. Overall, 184 (80.3%) patients were treated successfully with a single dose of MTX. For days 1 and 7 the optimal cutoff point was 7% reduction in β-hCG levels with sensitivity, specificity and PPV of 76.6% (69.9–82.5, 95% CI), 75.5% (60.5–87.1, 95% CI) and 92.8% (88.4–95.6, 95% CI), respectively. There was no significant difference between the protocols' AUC. None of the patients had any change of management during their day 4 visit in our 20 years of records. The cost for each visit day (day 4 and 7) was calculated with a total cost of 251 USD per patient. Conclusion: Patients treated with MTX for EP, measurement of day 1 and day 7 β-hCG serum levels has a cost minimization advantage and is not inferior to the traditional protocol for predictive accuracy and safety.