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Five-year outcomes after aquablation compared to TURP: The final WATER study results

  • Gilling P.J.,
  • WATER Investigators

Introduction & Objectives

To compare five-year safety and efficacy outcomes after Aquablation or transurethral resection of the prostate (TURP) for the treatment of lower urinary tract symptoms (LUTS) related to benign prostate hyperplasia (BPH).

Materials & Methods

181 patients with BPH were assigned at random (2:1 ratio) to either Aquablation or TURP. Patients and follow-up assessors at each site were blinded to treatment. Assessments included International Prostate Symptom Score (IPSS), Male Sexual Health Questionnaire (MSHQ), International Index of Erectile Function (IIEF) and uroflow (Qmax).


The primary safety endpoint was successfully achieved at 3 months where the Aquablation group had a lower event rate compared to TURP (26% vs. 42%, p=.0149 for superiority). The rate of persistent grade 1 events (all of which were retrograde ejaculation) at month 3 was lower (7% vs. 25%, p=.0004) after Aquablation and the rate of grade 2 and above events was similar across groups (20% for Aquablation vs. 23% for TURP, p=.3038). The primary efficacy endpoint was successfully achieved at 6 months where the mean IPSS decreased from baseline by 16.9 points for Aquablation and 15.1 points for TURP; the mean difference in change score at 6 months was 1.8 points larger for Aquablation (p<.0001 for non-inferiority, p=.1346 for superiority).
At five years, IPSS scores improved by 15.5 points in the Aquablation group and 13.5 points in TURP (p=.3768, 95% CI for difference -6.4 to 2.5 points). Improvements in maximum flow rate (Qmax) were large in both groups at 10.4 and 9.0 cc/sec for Aquablation and TURP, respectively (p=.9078, 95% CI for difference -4.3 to 7.0). PSA was reduced in both groups; the change in PSA at month 60 did not differ across groups (p=.9460).


Aquablation data at five years has been shown to be durable and consistent across all years of follow-up and comparable to TURP. Retrograde ejaculation rates were less for Aquablation.