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Randomized Controlled Trial
. 2022 Aug 11;387(6):506-513.
doi: 10.1056/NEJMoa2204253.

Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse

Mathew D Sorensen  1 , Jonathan D Harper  1 , Michael S Borofsky  1 , Tariq A Hameed  1 , Kimberly J Smoot  1 , Barbara H Burke  1 , Branda J Levchak  1 , James C Williams Jr  1 , Michael R Bailey  1 , Ziyue Liu  1 , James E Lingeman  1
Affiliations
Randomized Controlled Trial

Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse

Mathew D Sorensen et al. N Engl J Med. .

Abstract

Background: The benefits of removing small (≤6 mm), asymptomatic kidney stones endoscopically is unknown. Current guidelines leave such decisions to the urologist and the patient. A prospective study involving older, nonendoscopic technology and some retrospective studies favor observation. However, published data indicate that about half of small renal stones left in place at the time that larger stones were removed caused other symptomatic events within 5 years after surgery.

Methods: We conducted a multicenter, randomized, controlled trial in which, during the endoscopic removal of ureteral or contralateral kidney stones, remaining small, asymptomatic stones were removed in 38 patients (treatment group) and were not removed in 35 patients (control group). The primary outcome was relapse as measured by future emergency department visits, surgeries, or growth of secondary stones.

Results: After a mean follow-up of 4.2 years, the treatment group had a longer time to relapse than the control group (P<0.001 by log-rank test). The restricted mean (±SE) time to relapse was 75% longer in the treatment group than in the control group (1631.6±72.8 days vs. 934.2±121.8 days). The risk of relapse was 82% lower in the treatment group than the control group (hazard ratio, 0.18; 95% confidence interval, 0.07 to 0.44), with 16% of patients in the treatment group having a relapse as compared with 63% of those in the control group. Treatment added a median of 25.6 minutes (interquartile range, 18.5 to 35.2) to the surgery time. Five patients in the treatment group and four in the control group had emergency department visits within 2 weeks after surgery. Eight patients in the treatment group and 10 in the control group reported passing kidney stones.

Conclusions: The removal of small, asymptomatic kidney stones during surgery to remove ureteral or contralateral kidney stones resulted in a lower incidence of relapse than nonremoval and in a similar number of emergency department visits related to the surgery. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Veterans Affairs Puget Sound Health Care System; ClinicalTrials.gov number, NCT02210650.).

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Figures

Figure 1.
Figure 1.
Enrollment and Randomization.
Figure 2.
Figure 2.. Cumulative Incidence of Relapse.
Shaded areas represent 95% confidence intervals. Small circles represent censored data. Patient relapse data were censored when the patient did not have a relapse before being lost to follow-up or by the end of follow-up. CT denotes computed tomography.
Figure 3.
Figure 3.. Cumulative Incidence of New Stones in the Trial Kidney.
New stones were detected on CT. Small circles represent censored data. Shaded areas represent 95% confidence intervals.
See this image and copyright information in PMC

Comment in

References

    1. Boyce CJ, Pickhardt PJ, Lawrence EM, Kim DH, Bruce RJ. Prevalence of urolithiasis in asymptomatic adults: objective determination using low dose noncontrast computerized tomography. J Urol 2010;183:1017–21. - PubMed
    1. Assimos D, Krambeck A, Miller NL, et al. Surgical management of stones: American Urological Association/Endourological Society guideline. J Urol 2016;196:1153–69. - PubMed
    1. EAU guidelines. Presented at the EAU20 Virtual Congress, July 17–19, 2020.
    1. Keeley FX Jr, Tilling K, Elves A, et al. Preliminary results of a randomized controlled trial of prophylactic shock wave lithotripsy for small asymptomatic renal calyceal stones. BJU Int 2001;87:1–8. - PubMed
    1. Li S, Quarrier S, Serrell EC, Penniston KL, Nakada SY. Should we treat asymptomatic concurrent contralateral renal stones? A longitudinal analysis. Urolithiasis 2022;50:71–7. - PubMed

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