Transplant Trial Watch

Comparison of a magnetic retrieval device vs. flexible cystoscopy for removal of ureteral stents in renal transplant patients: A randomized controlled trial.

Kapoor, A., et al.

Canadian Urological Association Journal 2020 [record in progress].

The aim of this study was to assess the clinical and cost-related outcomes of conventional versus magnetic stents in deceased donor kidney transplant recipients.

Participants were randomly assigned to either a conventional stent or a Black-Star® magnetic stent.

41 patients scheduled to undergo deceased donor renal transplantation.

The primary endpoint was patient comfort of the stent in situ and following removal. The secondary endpoints were stent retrieval time, infection rate, cost-effectiveness, and to determine if it is feasible to conduct a larger randomized controlled trial.

6 weeks

CET Conclusions
This is an interesting RCT of magnetised ureteric stents that do not require a cystoscopy to remove, as they can be retrieved with a magnetic catheter. Patients were randomized using an online random number generator to standard JJ-stent and cystoscopic removal, or to magnetic “Black-Star” stents and magnetic catheter removal. The study was small (only 41 patients) so may not have been adequately powered for differences in some key outcomes (UTI for example). No power calculation is provided in the paper, so it is not clear how the study was powered for the primary outcome of patient comfort, assessed by a urological symptom score. The study found that retrieval of the magnetic “Black-Star” stents was significantly quicker than the cystoscopic removal of standard ureteric stents (4.8 minutes versus 6.6 minutes). The time measured however was from the time the patient entered the room, until the stent was removed, not the procedure time. One patient in the “Black-Star” group could not have the stent removed successfully with the magnetic catheter and had to have a cystoscopy. This patient’s results were excluded from the analysis, which is not best practice. There was no significant difference in symptom score with the stent in situ, or 1-week after removal. There was no significant difference in the rate of UTI, or patient-reported comfort on stent removal. The study did not have blinding for patients, clinical staff, or outcome assessors. Therefore, it is possible for bias to enter the results, particularly with a subjective outcome. The source of funding is not apparent in the report. Despite its small size and methodological shortfalls, this study does add to the evidence base for magnetic ureteric stents though and more studies should follow. If the magnetic stents are indeed as safe as standard JJ-stenting, then they may provide an alternative to reduce costs by removing the requirement for cystoscopy in all cases.

Jadad score

Data analysis
Per protocol analysis

Allocation concealment

Trial registration

Funding source
Not reported