Mini Percutaneous Nephrolithotomy Is a Noninferior Modality to Standard Percutaneous Nephrolithotomy for the Management of 20-40mm Renal Calculi: A Multicenter Randomized Controlled Trial

Abstract

Background: High quality of evidence comparing mini percutaneous nephrolithotomy (mPNL) with standard percutaneous nephrolithotomy (sPNL) for the treatment of larger-sized renal stones is lacking.

Objective: To compare the efficacy and safety of mPNL and sPNL for the treatment of 20-40mm renal stones.

Design, setting, and participants: A parallel, open-label, and noninferior randomized controlled trial was performed at 20 Chinese centers (2016-2019). The inclusion criteria were patients 18-70 yr old, with normal renal function, and 20-40mm renal stones.

Intervention: Percutaneous nephrolithotomy PNL was performed using either 18 F or 24 F percutaneous nephrostomy tracts.

Outcome measurements and statistical analysis: The primary outcome was the one-session stone-free rate (SFR). The secondary outcomes included operating time, visual analog pain scale (VAS) score, blood loss, complications as per the Clavien-Dindo grading system, and length of hospitalization.

Results and limitations: The 1980 intention-to-treat patients were randomized. The mPNL group achieved a noninferior one-session SFR to the sPNL group by the one-side noninferiority test (0.5% [difference], p < 0.001). The transfusion and embolization rates were comparable; however, the sPNL group had a higher hemoglobin drop (5.2 g/l, p < 0.001). The sPNL yielded shorter operating time (-2.2 min, p = 0.008) but a higher VAS score (0.8, p < 0.001). Patients in the sPNL group also had longer hospitalization (0.6 d, p < 0.001). There was no statistically significant difference in fever or urosepsis occurrences. The study's main limitation was that only 18F or 24F tract sizes were used.

Conclusions: Mini mPNL achieves noninferior SFR outcomes to sPNL, but with reduced bleeding, less postoperative pain, and shorter hospitalization.

Patient summary: We evaluated the surgical outcomes of percutaneous nephrolithotomy using two different sizes of nephrostomy tracts in a large population. We found that the smaller tract might be a sensible alternative for patients with 20-40mm renal stones.

Keywords: Mini; Percutaneous nephrolithotomy; Randomized controlled trial; Renal stone; Standard.