Comments on “A comparative analysis of tip-bendable suction ureteral access sheath versus traditional sheath in retrograde intrarenal stone surgery: a systematic review and meta-analysis of comparative studies”

Dear Editor,

I have carefully read the study titled “A comparative analysis of tip-bendable suction ureteral access sheath versus traditional sheath in retrograde intrarenal stone surgery: a systematic review and meta-analysis of comparative studies” by Guo et al, published in the International Journal of Surgery. This study systematically compares the efficacy and safety of TBS-UAS and traditional UAS in RIRS, providing new evidence for clinical ureteroscopy procedures. The article presents a detailed integration of data on immediate and final stone-free rates (SFR), complication control, and other key outcomes, especially the significant reduction in the incidence of fever, which has important clinical implications^[1].

While fully acknowledging the contributions of the article, I would like to offer a few supplementary suggestions from a methodological perspective to further deepen the academic discussion. These aspects were not fully addressed in the original manuscript but are relevant for enhancing the quality of the evidence, in line with the TITAN Guidelines 2025 on transparency in research reporting^[2].

In the current study, the authors used the Newcastle–Ottawa Scale (NOS) to assess the quality of the included studies. However, NOS is primarily used for evaluating observational study quality and is not appropriate for randomized controlled trials (RCTs). The NOS focuses on aspects such as patient selection, sample grouping, and exposure, which are important for observational studies^[3]. However, the quality assessment of RCTs needs to focus on issues such as the randomization process, allocation concealment, blinding, and data loss, which are unique sources of bias in RCTs. The Cochrane Risk of Bias 2.0 (RoB 2.0) tool is specifically designed for RCT assessment, offering a more detailed and precise analysis of issues such as randomization, blinding, allocation bias, and outcome assessment bias^[4]. The RoB 2.0 tool ensures that these key biases are accurately identified and controlled in the analysis, providing higher precision and scientific rigor in the quality evaluation of RCTs. Therefore, future studies should use the RoB 2.0 tool to replace NOS for the quality assessment of RCTs. This will ensure that specific biases in the study design are effectively identified and controlled, offering more precise and reliable results, and enhancing the rigor of the research.

Some outcomes, such as surgical time, had an I² value as high as 86.4%, indicating significant heterogeneity. The GRADE guidelines clearly state that when I² > 50%, downgrading should be considered. Specifically, if there is high heterogeneity, the outcome should be downgraded for “Inconsistency” to reflect the uncertainty^[5]. Unfortunately, the study did not address the analysis and downgrading of high heterogeneity, which may have introduced bias in the final assessment. Moreover, in the GRADE assessment, the risk of bias for certain outcomes was rated as “very serious,” yet the evidence level for these outcomes was ultimately rated as “Moderate,” which may present a logical inconsistency. According to GRADE guidelines, when the risk of bias is considered “very serious,” the evidence level should typically be downgraded by two levels, bringing it directly to “Low” to reflect the higher uncertainty. Keeping it at “Moderate” may lead to an overestimation of the confidence in the result. It is recommended that the GRADE evaluation be conducted using the GRADE software tool to standardize the analysis and directly export the results for more transparent and consistent assessment.

In conclusion, the study conducted by Guo et al provides strong evidence supporting the application of TBS-UAS in RIRS, especially through its detailed analysis of clinical outcomes, which is of great significance for the promotion of this technique. However, given that certain methodological details could be further optimized, we suggest that future studies use the RoB 2.0 tool for quality assessment of RCTs and conduct a more detailed and transparent analysis of downgrading factors in the GRADE evaluation. These improvements will provide a more robust basis for clinical decision-making and further advance the scientific development of this field.

Ethical approval

Not applicable as this article is a letter and does not report original research involving patients.

Consent

As this is a letter to the editor and no new research data or patient information has been included in this correspondence, data sharing and consent for publication are not applicable.

Sources of funding

This study did not receive any funding.

Author contributions

J.Y.: study concept and design, literature review, writing the paper; K.Z.: literature review, writing the paper.

Conflicts of interest disclosure

The authors declare no conflicts of interest.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Jian Yang.

Provenance and peer review

Not commissioned.

Data availability statement

Not applicable.