The prevalence and the severity of lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) is common and progressive.¹ Transurethral resection of the prostate has traditionally been the mainstay treatment for LUTS/BPH, but is associated with adverse effects including erectile dysfunction and retrograde ejaculation, and requires general anesthesia with hospital stays. These aspects increase the cost and impact the quality of life.²

Convective water vapor thermal therapy (CWVTT-Rezu-m™) is a minimally invasive surgical technique for LUTS/BPH that has been shown to produce clinically significant and durable results for up to 5 years.³ This therapy disrupts epithelial cell membranes by transferring stored thermal energy directly to prostatic tissue. Unlike transurethral needle ablation and transurethral microwave therapy, the thermal effects are confined to the transitional zone.⁴ An additional advantage is preservation of sexual function, including erection and ejaculatory function.⁵

While CWVTT has been shown to be clinically effective and provide rapid relief for LUTS/BPH, a subset of men experience a delay in their LUTS improvement following the procedure. In this study, we described patient- and treatment-specific risk factors that drive this delayed improvement, as this has not previously been investigated. We hypothesized that there are preoperative and perioperative risk factors that increase the likelihood for men to experience a delayed improvement in their LUTS following CWVTT.

In our study, patients who underwent CWVTT from January 2018 to December 2020 were retrospectively identified. Patient demographics, comorbidities, preoperative evaluation, intraoperative data, and postoperative outcomes were extracted for analysis. The primary outcome of our study was clinically significant improvement in LUTS 4 weeks following CWVTT, as defined by reaching the minimal clinically important difference (MCID) of a 25% improvement in International Prostate Symptom Score (IPSS). Conversely, delayed LUTS improvement was defined as a failure to reach a 25% improvement in the IPSS by 4 weeks. Patient-specific and treatment-specific risk factors were assessed using univariate and multivariate logistic regression to estimate the odds of delayed LUTS improvement.

Figure 1. Percent of patients with 25% improvement of LUTS over time following CWVTT. The likelihood of persistent LUTS following CWVTT decreased with time.

A total of 109 patients qualified for analysis, and 73% (80/109) of our patients had preoperative pressure flow studies performed. We found that 50% of men had clinically significant LUTS improvement (MCID >25%) at 1 month following CWVTT. Of the men 81.8% had clinically significant LUTS improvement at the time of their last followup (Fig. 1). We also found that as months following surgery increased, the probability that men reported LUTS decreased (Fig. 2). Overall, postoperative IPSS scores tended to decrease with time from CWVTT, indicating overall improvement in LUTS among the cohort (data not shown).

Lower bladder outlet obstruction index (BOOI) and prior surgical therapy for BPH were significantly associated with delayed LUTS improvement. The mean preoperative BOOI for patients with and without delayed LUTS improvement was 48.3 (SD=27.3) and 59.0 (SD=32.7), respectively. Every 10-unit increase in the preoperative BOOI was associated with a 15% decrease in the odds of delayed LUTS improvement (adjusted odds ratio [aOR]=0.85, p=0.01). Patients with prior surgical BPH therapy were 3.5 times more likely than those without prior surgical BPH therapy to experience delayed LUTS improvement following CWVTT (aOR=3.47, p=0.01). Finally, the odds of reaching the MCID increases by 9% with each additional month following CWVTT (aOR=0.91, p=0.003) (data not shown).

Figure 2. Probability of clinically significant LUTS following CWVTT. Following CWVTT, the probability of patients having LUTS decreases.

Postoperative time to gauge LUTS improvement and ­treatment efficacy was short in our cohort. However, our data suggest that regardless of an initial delayed LUTS improvement, most men will have clinically significant LUTS improvement by 1 year following CWVTT. This improvement was shown to be durable in initial randomized trials.³ Patients with lower BOOI and patients with prior surgical BPH therapy might not benefit as quickly from CWVTT, as these individuals are more at risk for a delayed improvement in their LUTS. For these patients, shared decision making and accurately weighing the risks and benefits of CWVTT with providers is important when proposing a treatment plan. These data provide novel insights into patient counseling and prioritize comprehensive review of patient characteristics and past medical history prior to CWVTT. Furthermore, our study lays the groundwork for prospective research for patients at risk for delayed LUTS improvement following CWVTT. STOP