Dear Editor,
We read with interest the RCT by Mantravadi and Rao [1] on ICSI outcomes following frozen embryo transfer in couples with male partners exhibiting elevated sperm DNA fragmentation (SDF) in the ejaculated semen. The trial randomly assigned 150 couples to either magnetic-activating cell sorting (MACS) or testicular sperm aspiration (TESA) to assess whether these sperm selection techniques improved ICSI outcomes. We commend the authors for conducting the first RCT on this topic. While the comparable live birth rates (LBRs) and higher implantation rates (IRs) in the MACS group are noteworthy, several critical methodological flaws must be addressed.
First, concerning inclusion criteria, the SDF threshold reported in the manuscript (30%) and the Clinical Trial Registry-India (25%) need to be consistent, or the discrepancy justified. The mean/median %SDF of the two groups (34%) is too close to the 30% threshold reported in the manuscript. However, no information is provided about the interquartile range or standard deviation/standard error of the two groups’ mean/median %SDF to allow readers to understand case distribution. Furthermore, it is unclear whether groups were comparable regarding other demographic features than patient age and baseline %SDF. A small sample-sized RCT simply must ensure such baseline comparability.
Second, the study lacks a defined primary outcome measure and a sample size estimation. Assuming a 45% LBR in both groups, 378 patients are required to ensure a two-sided 90% confidence interval excludes a difference between the groups of more than 15%, confirming no difference in LBRs. Similarly, to detect a significant increase in IR from 35 to 50%, as reported for TESA and MACS, respectively, with 80% power at the 5% significance level, 334 patients are needed. Thus, the present study (75 per group) lacks power and is prone to a type II error, calling the conclusions into question.
Third, the reporting of study endpoints needs to be more consistent. The IR was defined as the number of implanted embryos per the total number of transferred embryos. However, the authors reported IR per the total number of enrolled patients. The miscarriage rate was calculated per the total number of embryo transfers, deviating from the standard definition of spontaneous abortions per 100 clinical pregnancies [2]. The multiple pregnancy rate (MPR) was reported per embryo transfer rather than per live birth, complicating interpretation.
Additionally, the reporting of LBRs needs clarification. The authors stated that LBRs were based on the intention-to-treat (ITT) population and per embryo transfer (ET) cycle. Yet, they used the total number of patients per group as the denominator in both cases. ITT includes patients in the primary analysis within their respective treatment groups as assigned at randomization. Since there was no apparent cross-over or loss to follow-up, how do the authors explain the differences observed in LBRs per ITT (41.3% MACS; 44% TESA) and per ET (63% MACS; 56% TESA)?
The authors also report twice as high MPRs in the MACS group (8% vs. 4% in TESA). Without information on the number of embryos transferred per group, this suggests a potential bias in IRs and LBRs. Moreover, no embryological data is provided apart from the blastocyst conversion rate. Despite these issues, the authors claim that MACS significantly increases the likelihood of achieving a live birth compared to TESA, although non-significant LBR differences were reported.
Previous studies indicate no significant differences between sperm selection techniques like MACS or physiological intracytoplasmic sperm injection (PICSI) in embryological data, implantation, and pregnancy rates [3]. A study of 228 ICSI cycles with elevated SDF showed higher LBRs with TESA than ejaculated sperm, even when using advanced sperm selection techniques [4]. Another study reported higher rates of good-quality blastocysts in the TESA-ICSI group than ejaculated sperm [5]. Improved LBRs using testicular sperm from non-azoospermic males are attributed to lower SDF in TESA specimens [6, 7].
While the authors acknowledge the lack of a control arm and SDF results post-intervention, the study limitations are more critical, as outlined above. These limitations impede the interpretation of the findings. Given the potential adverse effects of SDF on IVF/ICSI outcomes and offspring health [8], the focus should be on selecting spermatozoa with optimal DNA quality. The search for the optimal sperm selection technique for males with elevated SDF continues.
Yours sincerely.
Author contribution
Sandro C. Esteves: Conceptualization and writing—original draft, review and editing; Sezcan Mumusoglu and Hakan Yarali: critical evaluation of statistical analyses, writing—review and editing; Peter Humaidan: writing—review and editing.
Declarations
Conflict of interest
SCE and HY report honoraria for lectures from Merck and Med.E.A. PH reports honoraria for lectures from Gedeon Richter, Merck, and IBSA. SM has nothing to disclose.
Footnotes
A Correspondence to this article was published on 09 September 2024.
Publisher's Note
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References
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