Letter to the editor

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Dear editor,

This letter is about the article “Systematic Review and Cumulative Analysis of the Managements for Proximal Impacted Ureteral Stones” published in World Journal of Urology in 2019 [1]. While preparing a speech about impacted proximal ureteral stones for a congress I was invited to recently, I read the meta-analysis of Deng et al. I have encountered some errors in the study which contains high value data on the subject.

In Fig. 8(b), which included meta-analyses of the auxilliary procedure, I found the details of the studies of Qi et al. and Yang et al. doubtful.

I then examined the original results of the works I mentioned above. It was reported that 20 patients who underwent URS need flexible ureteroscopy in the postoperative period, and none of the patients with PCNL required an auxilliary procedure in the study of Qi et al. [2]. The data in meta-analysis belong to patients who do not need auxilliary procedure.

Also, it is seen that none of the 91 patients who underwent mini-PCNL showed postoperative SWL requirement (auxilliary procedure), whereas 21 of the 91 patients who underwent URS required SWL for residual stones in Table 2 from the study of Yang et al. [3]. The auxilliary procedure data of PCNL and URS obtained from Yang et al.’s study was reversed in the meta-analysis.

All these errors overshadowed the forest plot analyses, which were expected to show a significant difference in favor of mini-PCNL. However, a more remarkable effect can be seen in Table 3.2.2 in Fig. 8b, where the results that should be in favor of PCNL have turned in favor of URS.

To prevent the scientific value of the study from becoming controversial, the above corrections have been presented to the attention of the authors.

Sincerely yours,

Oktay Özman, MD


  1. 1.

    Deng T, Chen Y, Bing Liu M, Laguna P, de la Rosette JJMCH, Duan X, Wenqi Wu, Zeng G (2019) Systematic review and cumulative analysis of the managements for proximal impacted ureteral stones. World J Urol 37(8):1687–1701

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  2. 2.

    Qi S, Li Y, Liu X, Zhang C, Zhang H, Zhang Z, Xu Y (2014) Clinical efcacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy for large impacted proximal ureteral calculi: a prospective, randomized study. J Endourol 28:1064–1070

    Article  Google Scholar 

  3. 3.

    Yang Z, Song L, Xie D et al (2012) Comparative study of outcome in treating upper ureteral impacted stones using minimally invasive percutaneous nephrolithotomy with aid of patented system or transurethral ureteroscopy. Urology 80:1192–1197

    Article  Google Scholar 

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Correspondence to Oktay Özman.

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Özman, O. Letter to the editor. World J Urol 39, 293 (2021). https://doi.org/10.1007/s00345-020-03194-z

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