Session: PD28: Stone Disease: Surgical Therapy (including ESWL) III
PD28-11: A proposed mathematical model to help preoperative planning between RIRS and MiniPerc for renal stones between 10 and 20 mm using Holmium:YAG laser (Cyber Ho): the Stone Management According to Size-Hardness (SMASH) score
Introduction: We performed a prospective randomized comparison between Retrograde IntraRenal Surgery (RIRS) and MiniPerc (MP) for stones between 10 and 20 mm to evaluate the performance of a mathematical model to drive preoperative planning. Methods: Patients with a single renal stone between 10-20 mm were enrolled. Exclusion criteria were age < 18 or > 75, presence of acute infection, coagulation impairments, cardiovascular or pulmonary comorbidities. For each patient a mathematical model named Stone Management According to Size-Hardness (SMASH) score was so calculated: hounsfield units (HU) x stone maximum size (cm) / 100. Patients were divided into 4 groups according to type of treatment and SMASH score: RIRS with score < 15 (Group A), RIRS with score = 15 (Group B), MP with score < 15 (Group C), MP with score = 15 (Group D). In all groups the Cyber Ho laser device was used. A CT scan after 3 months was performed. A negative CT scan or asymptomatic patients with stone fragments < 3 mm were the criteria to assess the stone-free status. A statistical analysis was carried out to assess efficacy and safety of each procedure. Results: 350 patients were enrolled (87 in Group A, 88 in Group B, 82 in Group C, 93 in Group D). Mean stone size was 13.1 vs 13.3 mm in Group A vs B (p=0.18) and 16.2 vs 18.1 mm in Group C vs D (p=0.12). The overall stone free rate (SFR) was 82%, 61%, 75% and 85% for Group A, B, C and D, respectively. SFR was comparable when comparing Group C and D (p=0.32) and Group A and C (p=0.22). On the contrary, SFR was significantly higher in Group A over B (p=0.03) and in Group D over B (p=0.02). Complication rate was 2.2%, 3.4%, 12.1% and 12.9% for Groups A, B, C and D, respectively. The difference was significant between Groups A and C (p=0.02) and Groups B and D (p=0.02). Conclusions: RIRS and MP are both safe and effective to obtain a postoperative SFR with Cyber Ho. The mathematical model taking into account HU with the proposed cut-off allowed a proper allocation of the patients between endoscopic and percutaneous approach. SOURCE OF Funding: None
