Longitudinal Functional Outcomes Following Rezūm Water Vapor Therapy: A 24-Month Analysis of 1,238 Patients

Technical Summary: Longitudinal Functional Outcomes Following Rezūm Water Vapor Therapy

Problem Statement
Benign prostatic hyperplasia (BPH) is a prevalent chronic condition causing lower urinary tract symptoms (LUTS) and reduced quality of life (QoL) in aging men. While minimally invasive surgical therapies (MISTs) like Rezūm water vapor therapy have emerged as effective alternatives to transurethral resection of the prostate (TURP), there is a scarcity of large-scale, contemporary studies evaluating the durability of functional outcomes beyond the immediate postoperative period. Existing literature often suffers from small sample sizes, incomplete follow-up, and limited assessment of objective functional metrics. Furthermore, there is insufficient data regarding predictors of long-term response, retreatment rates, and the impact of baseline bladder dysfunction on treatment durability.

Methodology
This study employed a retrospective cohort design involving 1,238 consecutive patients treated with Rezūm convective water vapor therapy at five international ambulatory surgical centers between April 2022 and May 2025.

• Population: Patients with bothersome LUTS refractory to medical management or electing treatment. Exclusion criteria included indwelling catheters, neurogenic bladder, active urinary tract infection, recent outlet surgery, or missing baseline data.
• Intervention: Procedures were performed by experienced surgeons using the Rezūm System, with treatment individualized based on gland size and configuration. Patients were discharged with a temporary Foley catheter, typically removed on day 5.
• Data Collection: Baseline assessments included demographics, prostate volume, transition zone volume, median lobe presence, International Prostate Symptom Score (IPSS), QoL, peak urinary flow rate (Qmax), and post-void residual (PVR). Follow-up occurred at 3, 6, 12, and 24 months.
• Statistical Analysis: The study utilized longitudinal mixed-effects models to assess changes in IPSS, QoL, Qmax, and PVR. Clinical durability was analyzed via Kaplan-Meier survival analysis (retreatment-free survival, freedom from retention). Multivariable logistic regression and proportional hazards modeling identified predictors of outcomes. Model performance was evaluated using receiver operating characteristic (ROC) curves, calibration plots, and decision curve analysis.

Key Contributions

• Scale and Duration: This represents one of the largest published cohorts (n=1,238) evaluating contemporary functional outcomes of Rezūm therapy with a 24-month longitudinal assessment.
• Objective Metrics: Beyond subjective symptom scores, the study rigorously analyzed objective measures including Qmax, PVR, and voided volume to provide a comprehensive view of treatment efficacy.
• Predictive Modeling: The research developed and validated predictive models to identify baseline factors associated with durable response and clinical failure, utilizing modern analytics (AUC, decision curve analysis).
• Subgroup Analysis: The study specifically examined outcomes in patients with large prostates (>80 mL) and those with median lobes, addressing common clinical concerns regarding patient selection.

Results

• Functional Improvement: Significant improvements were observed across all metrics. Mean IPSS decreased from 23.1 at baseline to 8.4 at 24 months (p<0.001). Mean QoL improved from 4.8 to 1.8. Qmax increased from 8.7 mL/s to 16.0 mL/s (an ~84% improvement), and mean PVR decreased from 146 mL to 56 mL (>60% reduction). Improvements were evident by 3 months and remained stable through 24 months.
• Durability: The 24-month retreatment-free survival rate exceeded 95%. Rates of freedom from urinary retention and re-catheterization remained high throughout the follow-up period.
• Predictors of Outcome: Multivariable analyses identified elevated baseline PVR and a history of urinary retention as the principal independent predictors of less favorable long-term outcomes, including lower odds of durable response and higher retreatment rates.
• Non-Significant Factors: Age, BMI, baseline prostate volume, and the presence of a median lobe showed only modest or no significant impact on long-term outcomes. Specifically, patients with prostate volumes >80 mL did not demonstrate statistically significant differences in durable response or complication rates compared to those with smaller glands.
• Model Performance: Predictive models demonstrated good discrimination (AUC ~0.78 for durable response; >0.80 for clinical failure) and calibration.

Significance and Claims
The paper claims that Rezūm therapy provides durable improvements in urinary symptoms, quality of life, urinary flow, and bladder emptying for up to 24 months in a large, real-world cohort. The study establishes that clinical durability is high, characterized by low retreatment rates and excellent patient satisfaction.

Crucially, the authors assert that baseline bladder dysfunction—specifically elevated PVR and a history of urinary retention—is the primary determinant of long-term outcome. This finding suggests that clinicians should temper expectations for patients with significant pre-existing bladder dysfunction and consider preoperative optimization of bladder function. Conversely, the data indicates that prostate volume and the presence of a median lobe are less critical factors in predicting success, potentially broadening the candidate pool for Rezūm therapy. The study concludes that while predictive models show promise for tailoring patient counseling and postoperative management, external validation is required before clinical implementation.