Hypothesis / aims of study
Lower urinary tract symptoms (LUTS) are a frequently encountered problem, which are often difficult to treat. OAB is defined as urgency, with or without urinary incontinence, usually with nocturia and frequency. These symptoms can have an important negative impact on a patient’s quality of life. OAB can be divided in either neurogenic OAB (nOAB) or idiopathic OAB (iOAB). Intravesical onabotulinum toxin-A injections (BoNT-A) are an efficacious and safe treatment option for patients suffering from iOAB. Evidence regarding long-term results in male iOAB patients is limited and rarely focuses on the effects after prior prostatic surgery. The aim of this study is to identify the long-term efficacy and treatment persistency of repeated intravesical BoNT-A injections in male iOAB patients after prior prostatic surgery (i.e. desobstructive surgery or radical prostatectomy).
Study design, materials and methods
In this retrospective, single-centre study, data from 477 patients who received BoNT-A treatment between 2004 and 2018 was collected and evaluated. Outcome data of 120 male patients with idiopathic OAB refractory to anticholinergic therapy, with collectively 207 BoNT-A injections, was analysed and presented. Both patients with urgency incontinence (OAB wet) and urgency without incontinence (OAB dry) were included. Before start of BoNT-A treatment, a specialised nurse taught patients how to perform clean intermittent self-catheterization (CISC) in case necessary. The need for CISC was evaluated after treatment by measuring the post-void residual (PVR). Patients with a PVR of >150 ml were advised to perform CISC. All intravesical BoNT-A injections were performed cystoscopically by an experienced urologist, either under general anesthesia or under local anesthesia at the outpatient clinic. The total administered dosage ranged between 100 and 300 units per patient, at a concentration of 1 unit per milliliter.
The mean age at first BoNT-A injection was 72 years (62 – 81 years). The median duration of follow-up was 23 months (6 – 65 months). Twenty-three cases of urinary tract infections (11.1%) following BoNT-A treatment were recorded. A total of 40 patients (33.3%) required CISC during follow-up, of whom 20 patients already performed CISC before the start of BoNT-A treatment. No other adverse events were recorded. The median inter-injection time was 11.5 months (9 – 21 months). At last point of follow-up, 35 patients (29.2%) were still on active treatment. Of the 85 patients who discontinued treatment, 54 (63.5%) stopped due to no or insufficient effect, 28 (32.9%) stopped due to improvement of their symptoms and 3 (3.5%) stopped after urinary retention requiring clean intermittent self-catheterization (CISC). The remaining 28 patients (32.9%) reported improvement of their symptoms after BoNT-A treatment but didn't require any further injections. In total, 20 patients (16.7%) required CISC after BoNT-A treatment. Three subgroups were identified: 56 patients without prior prostate surgery, 40 patients with transurethral resection of prostate (TURP) and 24 patients with radical prostatectomy (RP) prior to BoNT-A treatment. Discontinuation rates across the thee groups were similar, but a significant difference in post-treatment CISC (P = 0.021) was seen. The necessity of catheterization after BoNT-A treatment differs for the group without surgery, the TURP-subgroup and RP-group, with 26.8%, 10.0% and 4.2% respectively. The odds of new CISC after BoNT-A treatment was significantly higher for the group without prior surgery compared to both the TURP-subgroup, with an OR of 3.29 (95% CI: 1.001-10.827; P = 0.050), and the RP-subgroup, with an OR of 8.41 (95% CI: 1.043-67.872; P = 0.046).
Interpretation of results
The effect (none, insufficient or satisfactory) of the BoNT-A treatment did not differ significantly across the three groups. However, what did stand out was the number of patients that required CISC after BoNT-A treatment. At almost twenty-seven percent, the CISC percentage is much higher for the subgroup without prior prostate surgery compared to the TURP- and RP-subgroup (ten and four percent respectively). Since the rate of patients with prior use of catheter (CISC or indwelling) was similar for the three subgroups, it does not explain the before-mentioned significant difference in de novo CISC. This finding, in addition to the lower discontinuation rate for the RP-subgroup, indicates that BoNT-A treatment is tolerable for patients with prior radical prostatectomy. This favorable outcome for the RP-subgroup corresponds with findings of Habashy et al., where patients that had undergone RP prior to BoNT-A treatment showed the greatest subjective improvement in urinary symptoms, as well as a statistically significant reduction in pad usage. (1) Another study conducted by Rahnama’i et al. compared four subgroups: idiopathic OAB without surgery, neurogenic OAB, post-TURP and post-RP OAB. Following the neurogenic OAB-subgroup, the RP-subgroup had the highest success rate at 29%, compared to 21% in the subgroup without prior surgery and 11% in the TURP-subgroup. (2)