This study, known as the FLAME Trial (Flexible ureteroscopy for Lower pole stones And Mini-pErcutaneous nephrolithotomy), is an international, multicenter, randomized, non-inferiority trial. It aims to compare the effectiveness and safety of flexible ureteroscopy using a flexible and navigable suction ureteral access sheath (FANS) versus mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower pole kidney stones. A total of 640 eligible adult patients will be enrolled across 20 high-volume urology centers in China, Russia, Turkey, and India. Participants will be randomly assigned to undergo either FANS-assisted flexible ureteroscopy or mini-PCNL. The primary outcome is the immediate stone-free rate (SFR) assessed by non-contrast CT within 72 hours after surgery. Secondary outcomes include SFR at 1 month, operative time, pain score, length of hospital stay, complication rates, and changes in health-related quality of life. The goal of this trial is to determine whether the less invasive FANS-assisted approach is non-inferior to mini-PCNL in terms of efficacy, while potentially offering advantages in postoperative recovery and safety.
The FLAME Trial (Flexible ureteroscopy for Lower pole stones And Mini-pErcutaneous nephrolithotomy) is an international, multicenter, prospective, randomized, controlled, non-inferiority study that aims to evaluate the safety and efficacy of flexible ureteroscopy assisted by a Flexible and Navigable Suction Ureteral Access Sheath (FANS) compared with mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower pole renal stones. This trial will enroll 640 patients from 20 urology centers with substantial experience in endoscopic stone surgery, including hospitals in China, Russia, Turkey, and India. Eligible participants will be randomly assigned in a 1:1 ratio to either the FANS-assisted flexible ureteroscopy group or the mini-PCNL group. All patients will undergo preoperative imaging, intraoperative standardization, and postoperative follow-up according to the study protocol. The primary endpoint is the stone-free rate (SFR) within 72 hours postoperatively, evaluated by non-contrast-enhanced computed tomography (NCCT). Secondary endpoints include SFR at 1 month, operative time, length of hospital stay, postoperative pain (measured by VAS score), complication rates (graded by Clavien-Dindo classification), changes in renal function, and health-related quality of life (HRQoL). The FANS, developed to improve irrigation control and active stone fragment suction during flexible ureteroscopy, may provide better visualization, reduce intrarenal pressure, and shorten operative time. By directly comparing FANS-assisted fURS with mini-PCNL, the trial seeks to determine whether a less invasive method can achieve comparable outcomes in terms of stone clearance and complication rates.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
640
The FANS with negative-pressure suction, enhancing intrarenal pressure control and fragment evacuation during flexible ureteroscopy.
Mini-PCNL is performed under general anesthesia with less than 20 Fr access tract, using rigid nephroscopy and stone fragmentation under direct visualization. Postoperative drainage is provided via nephrostomy or ureteral stent as per protocol.
The First Affiliated Hospital of Guangzhou Medical University
Guangzhou, Guangdong, China
RECRUITINGImmediate Stone-Free Rate (SFR)
Stone-free status will be evaluated using non-contrast-enhanced computed tomography (NCCT) performed within 72 hours after surgery. Stone-free is defined as the absence of residual stone fragments or presence of clinically insignificant fragments ≤2 mm.
Time frame: 72 hours after surgery
Final Stone-Free Rate (SFR) at 1 Month
Assessed by low-dose CT scan. Patients with no residual stones or with residual fragments ≤2 mm are defined as stone-free.
Time frame: 1 month after surgery
Operative Time
For the FANS-fURS group, operative time is defined as the duration from insertion of the endoscope into the urethra to completion of stent placement. For the mini-PCNL group, it is defined as the time from retrograde placement of the ureteric catheter to nephrostomy tube placement or percutaneous access removal.
Time frame: Intraoperative
Postoperative Pain Level
Evaluated using the 10-point Visual Analog Scale (VAS), where 0 indicates no pain and 10 indicates worst pain.
Time frame: Within 24 hours after surgery.
Length of Hospital Stay
From surgery to discharge.
Time frame: From the day of surgery until the day of discharge, assessed up to 30 days postoperatively.
Complication Rate Within 1 Month
All postoperative complications will be recorded and graded using the Clavien-Dindo classification system.
Time frame: 1 month after surgery.
Change in Quality of Life Score
Assessed using the Wisconsin Stone Quality of Life (WISQOL) questionnaire before surgery and at 1-month follow-up.
Time frame: Baseline and 1 month after surgery.
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