To the Editor,
We perceive a need to comment on the study by Kahraman et al., [1] who retrospectively compared the IVF outcomes of patients who had only a single good-quality blastocyst and underwent transfer either with (n = 1126) or without preimplantation genetic testing for aneuploidy (PGT-A) (n = 938). The PGT-A group had 225 and the non-PGT-A group had 938 single euploid embryo transfer cycles.
Using a generalized linear mixed model (GLMM), the authors concluded that in PGT-A cases, regardless of other variables, the probabilities of clinical pregnancy and live birth were found to be, respectively, 3.907- and 3.448-fold higher than in non-PGT-A cases (P < 0.001), with a 1.943-fold higher (P = 0.013) probability of a total pregnancy loss in non PGT-A cases. They, therefore, concluded that in the presence of only a single blastocyst PGT-A significantly increased clinical pregnancy and live birth rates and, regardless of age, decreased total pregnancy losses.
Evidence for the clinical utility of PGT-A remains ambiguous [2–4], due to statistical biases from outcome reporting with reference to embryo transfer. Once their data set is reanalyzed with outcomes reported with reference to cycle start (i.e., intent to treat) quite different conclusions are reached.
It then becomes apparent that only 115 of their 1126 patients (10.2%) in the PGT-A group achieved a live-birth, compared to 278 out of 938 (29.6%) in the control group (P < 0.0001). In practical terms this, furthermore, means that in 218 [(1126*29.6%)-115] cycles in the PGT-A group, embryos were discarded despite their potential ability to implant and reach delivery.
Viewed in this light the authors’ claim of outcome benefits for PGT-A utilization in patients with only a single blastocyst are much less apparent and possibly even compromising to IVF cycle outcome chances, especially in patients with small embryo numbers.
Finally, it would have been better to calculate on a per cycle rather than a per-transfer basis. Even one blastocyst reflects favorable patient selection in comparison to infertile women with not even one transferrable embryo at blastocyst-stage.
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References
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