Does a prediction model for pregnancy of unknown location developed in the UK validate on a US population?

K.T. Barnhart1,2,*, M.D. Sammel2, D. Appleby2, M. Rausch1, T. Molinaro1, B. Van Calster3, E. Kirk4, G. Condous5, S. Van Huffel3, D. Timmerman6 and T. Bourne6,7
A logistic regression model (M4) was developed in the UK to predict the outcome for women with a pregnancy of unknown location (PUL) based on the initial two human chorionic gonadotrophin (hCG) values, 48 h apart. The purpose of this paper was to assess the utility of this model to predict the outcome for a woman (PUL) in a US population.