Transurethral resection of the prostate (TURP) is the gold standard for benign prostatic hyperplasia (BPH) surgery and has good long-term outcomes. However, there are some reports that although the International Prostate Symptom Score (IPSS) and QOL scores improve dramatically immediately after surgery, they gradually deteriorate over the next 10 years (1). Furthermore, a decrease in the maximum flow rate (Qmax) has been reported as one of the causes of IPSS deterioration (2). The postoperative decrease in Qmax may be due to either recurrence of bladder outlet obstruction due to urethral stricture or recurrence of adenoma, or a decrease in detrusor contractility. The aim of our study was to prospectively assess the impact of TURP on detrusor function at 5 years after surgery.

We carried out a single center prospective observational study in a university hospital. The study was approved by the institutional review board of the hospital. This trial was registered with the UMIN Clinical Trials Registry. Sixty consecutive patients were prospectively enrolled and underwent TURP from November 2014 to November 2018. The patients had lower urinary tract symptoms (LUTS) secondary to BPH and were planned to undergo surgery according to the Japanese Urological Association guidelines for BPH. Exclusion criteria were a history of prostate, bladder or urethral surgery or neurological disease. For postoperative management, the use of all urological medications taken before surgery was discontinued immediately after TURP, and if LUTS persisted or newly appeared after surgery, the options considered were administration of urological medications, repeat TURP and surgery for urethral stricture. Furthermore, regardless of whether there was LUTS or not, if the bladder outlet obstruction index (BOOI) was 40 or higher on pressure flow study (PFS) performed postoperatively, endoscopy of the urethra was performed to clarify whether the cause of the obstruction was urethral stricture or residual or relapsed adenoma. At 6, 24 and 60 months postoperatively, free uroflowmetry (UFM) and PFS were performed and the IPSS, overactive bladder symptom score (OABSS) were determined. PFS was performed according to the standard methods defined by the ICS. The primary endpoint was the change of the bladder contractility index (BCI), which was defined by the following formula: detrusor pressure at Qmax (PdetQmax) + 5Qmax. The secondary endpoints were the changes of the IPSS, QOL score, OABSS, UFM and PFS parameters, including the BOOI, which was defined by the following formula: PdetQmax - 2Qmax. Furthermore, to evaluate the outcomes by age, we divided the age groups at 70 years and defined the younger group as those under 70 years old, and the elderly group as those aged 70 years or older.

Table 1 shows the characteristics of the intention-to-treat 60 patients at baseline. The IPSS total score and OABSS total score were significantly higher in the older group than in the younger group. There were no significant differences between the two groups in other variables, including the BCI (younger, 110 vs. elderly, 106). The mean duration of surgery was 83 minutes and the mean resected tissue weight was 21g. There was no significant difference between the groups regarding these 2 variables. Of the 60 patients, 39 completed our protocol. Of the 21 patients who were unable to complete the protocol, 6 refused PFS testing, 5 could not be contacted, 4 had difficulty coming to the hospital due to poor physical condition, 3 died, 2 could not void in PFS, and one dropped out due to PFS machine failure during the postoperative follow-up period. Three patients (7.7%) received urological medications and no patients underwent urethral stricture surgery or repeat BPH surgery during the follow-up period. Table 2 shows the outcomes of questionnaire, UFM and PFS during the follow-up period in per protocol analysis. In the 39 patients who completed the protocol, the BOOI at 6 months (6.3), 24 months (15.2), and 60 months (14.0) after surgery was significantly lower than that before surgery (59.3). This trend was the same even when the patients were divided by age into the elderly and young groups. On the other hand, the BCI showed no significant change from preoperative values up to 60 months after surgery in all 39 patients. However, in the elderly group, the BCI was significantly decreased 60 months (85.6) after surgery compared to before surgery (102) (p=0.02), which was not observed in the younger group (Figure). Furthermore, the maximum cystometric capacity (MCC) at 60 months (398ml) was significantly higher than the preoperative value (356ml) (p=0.03), but this was not observed at 6 or 24 months in any of the 39 patients. The same was observed in the younger group (preoperatively, 362ml vs. 60 months after surgery, 431ml, p=0.03), but no significant change in the MCC was observed up to the time of final evaluation in the elderly group. The IPSS, QOL, and OABSS remained significantly lower than the preoperative data until 60 months after surgery, regardless of age (all, p<0.01).

This is the first study that prospectively evaluated the detrusor function by PFS up to 5 years after TURP. The present study revealed that if surgery for BPH is performed at an older age, the detrusor contractility gradually decreases after surgery. One possible reason why detrusor contractility decreases in elderly patients is that as people get older, they are more likely to suffer from various vessel and nerve diseases, such as diabetes, hypertension, and dyslipidemia, which are reported as the causes of detrusor contractility decline. However, in this study, there were no significant differences between age groups regarding comorbidities. When an elderly patient complains of voiding symptoms such as slow stream several years after BPH surgery, we should suspect that the patient's detrusor contractility is decreasing. Furthermore, the patient's age should be considered when deciding whether to perform BPH surgery, and specifically, we may need to recommend surgery at a younger age. Moreover, if surgery is performed at a younger age, the MCC will significantly increase over the long term compared to the time of surgery, so it is likely to be advantageous in terms of improving storage symptoms. There are several limitations to the study. The first is that the planned number of patients was small. Since the study was conducted at a single institution, it took much time, approximately four years, to collect the planned patients. The second is that many patients, 35%, dropped out. The reasons for the high number of drop outs is that it took a very long period of five years to complete the protocol and, since PFS is an invasive test, some patients refused to undergo it during the protocol.

We prospectively evaluated the detrusor contractility up to 5 years after TURP. Detrusor contractility was significantly reduced in the elderly, in spite of which the relief of bladder outlet obstruction was maintained 5 years after surgery.

Masumori N, Furuya R, Tanaka Y, Furuya S, Ogura H, Tsukamoto T. The 12-year symptomatic outcome of transurethral resection of the prostate for patients with lower urinary tract symptoms suggestive of benign prostatic obstruction compared to the urodynamic findings before surgery. BJU Int. 2010;105:1429-1433.
Hoekstra RJ, Van Melick HH, Kok ET, Ruud Bosch JL. A 10-year follow-up after transurethral resection of the prostate, contact laser prostatectomy and electrovaporization in men with benign prostatic hyperplasia; long-term results of a randomized controlled trial. BJU Int. 2010;106:822-826.

Continence 12S (2024) 101379
DOI: 10.1016/j.cont.2024.101379