Saline-assisted Fascial Exposure Microultrasound-guided Nerve Preservation During Robotic Prostatectomy: Interim Analysis of a Randomized Controlled Trial.

Abstract

Background: Erectile dysfunction remains a major morbidity after radical prostatectomy. The SAFE technique uses real-time, micro-ultrasound-guided low-pressure hydrodissection to enable atraumatic nerve sparing.

Objective: We compared functional and oncologic outcomes of SAFE versus standard robotic-assisted radical prostatectomy (RARP).

Design, setting, and participants: In this randomized trial, patients were assigned 1:1 to micro-ultrasound-guided SAFE-RARP or standard RARP. Surgeons were unblinded; patients and outcome assessors were blinded.

Outcome measurements and statistical analysis: The primary endpoint was erectile function recovery at 6 mo (SHIM ≥17), with secondary functional and oncologic outcomes. The primary endpoint was assessed at the prespecified interim analysis using a one-sided pooled z-test within a group-sequential O'Brien-Fleming α-spending framework (interim efficacy boundary, one-sided p < 0.002).

Results and limitations: A total of 107 patients were analyzed (SAFE, n = 54; control, n = 53). At 6 mo, erectile function recovery was higher with SAFE than with standard RARP (52% vs 43%; absolute difference 8.5%, 95% CI -10% to 27%; one-sided p = 0.22), without crossing the prespecified interim efficacy boundary. At 6 weeks, early recovery rates were higher with SAFE (37% vs 21%; one-sided p = 0.032), with a smaller difference at 3 mo. Linear mixed-effects modeling showed earlier improvement in SHIM with SAFE, with convergence by 6 mo. Continence, oncologic outcomes, and complication rates were similar between groups. Limitations include the prespecified interim nature of the analysis, the relatively small sample size, and the need for longer follow-up to determine the durability and clinical significance of functional differences.

Conclusions: In this prespecified interim analysis, the primary endpoint of 6-mo recovery was not met. Exploratory analyses suggested earlier postoperative recovery with SAFE, without evidence of compromised safety or oncologic outcomes; these findings are hypothesis-generating.