Performance of Day 5 KIDScore™ morphokinetic prediction models of implantation and live birth after single blastocyst transfer

Purpose While several studies reported the association between morphokinetic parameters and implantation, few predictive models were developed to predict implantation after day 5 embryo transfer, generally without external validation. The objective of this study was to evaluate the respective performance of 2 commercially available morphokinetic-based models (KIDScore (TM) Day 5 versions 1 and 2) for the prediction of implantation and live birth after day 5 single blastocyst transfer. Methods This monocentric retrospective study was conducted on 210 ICSI cycles with single day 5 embryo transfer performed with a time-lapse imaging (TLI) system between 2013 and 2016. The association between both KIDScore (TM) and the observed implantation and live birth rates was calculated, as well as the agreement between embryologist's choice for transfer and embryo ranking by the models. Results Implantation and live birth rate were both 35.7%. A significant positive correlation was found between both models and implantation rate (r = 0.96 and r = 0.90, p = 0.01) respectively. Both models had statistically significant but limited predictive power for implantation (AUC 0.60). There was a fair agreement between the embryologists' choice and both models (78% and 61% respectively), with minor differences in case of discrepancies. Conclusions KIDScore (TM) Day 5 predictive models are significantly associated with implantation rates after day 5 single blastocyst transfer. However, their predictive performance remains perfectible. The use of these predictive models holds promises as decision-making tools to help the embryologist select the best embryo, ultimately facilitating the implementation of SET policy. However, embryologists' expertise remains absolutely necessary to make the final decision.