WATER versus WATER II 2-Year Update: Comparing Aquablation Therapy for Benign Prostatic Hyperplasia in 30–80-cm3 and 80–150-cm3 Prostates

Abstract Background Surgical options are limited when treating large (>80 cm3) prostates for lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH). Open simple prostatectomy remains the most common procedure performed for large prostates. There is a need for novel surgical approaches with shorter learning curves and effective treatment. Aquablation could be this novel tool. Objective To compare the outcome of Aquablation for 30–80-cm3 prostates with the outcome for 80–150-cm3 prostates at 2-yr follow-up. Design, setting, and participants We used data from two trials. WATER is a prospective, double-blind, multicenter, international clinical trial comparing the safety and efficacy of Aquablation and transurethral resection of the prostate in the treatment of LUTS/BPH in men aged 45–80 yr with a prostate of 30–80 cm3. WATER II is a prospective, multicenter, single-arm international clinical trial of Aquablation in men with a prostate of 80–150 cm3. Intervention Aquablation, an ultrasound-guided, robotically executed waterjet ablative procedure. Outcome measurements and statistical analysis We compared 24-mo outcomes between 116 WATER and 101 WATER II study subjects. Student’s t test or a Wilcoxon test was used to compare continuous variables and Fisher’s test for categorical variables. Results and limitations The International Prostate Symptom Score (IPSS) reductions at 24 mo was 14.5 points for WATER and 17.4 points for WATER II (p = 0.31). At baseline, the maximum urinary flow rate (Qmax) was 9.4 and 8.7 cm3/s in WATER and WATER II, improving to 20.5 and 18.2 cm3/s, respectively (p = 0.60) at 24 mo. Improvements in both IPSS and Qmax were immediate and sustained throughout follow-up. At 2 yr, the surgical retreatment rate was 4% in WATER and 2% in WATER II. Conclusions Aquablation is effective in patients with a prostate of 30–80 cm3 and patients with a prostate of 80–150 cm3 treated for LUTS/BPH, with comparable outcomes in both groups. It has low complication and retreatment rates at 2 yr of follow-up, with durable improvements in functional outcome. Patient summary Outcomes of Aquablation for both small-to-moderately-sized and large prostates are similar and sustainable at 2 yr of follow-up.