Intravesical prostatic protrusion does not compromise the therapeutic effects of Mirabegron in male patients with overactive bladder

Abstract

Intravesical prostatic protrusion (IPP) is associated with the degree of benign prostatic obstruction. We evaluated the effects of Mirabegron, a selective β3 adrenoceptor agonist, on overactive bladder (OAB) in male patients with different degrees of IPP. About 185 male patients ≥40years with lower urinary tract symptoms were recruited from a tertiary referral center. OAB was defined by the overactive bladder symptom score (OABSS) urgency score of ≥2 and sum score of ≥3. IPP was measured in the midsagittal section using transrectal ultrasound and patients were divided into IPP ≤5mm and IPP >5mm groups. Outcomes were assessed at the baseline, 4, and 12weeks. About 104 patients (56.2%) were diagnosed with OAB and received Mirabegron (50mg) daily use. Both IPP groups (≤5 and >5mm) had similar baseline OABSS and International Prostate Symptom Scores (IPSS). Four-week Mirabegron usage was associated with significant decreases in both symptom score measurements, OABSS: IPP ≤5mm -27.4% and IPP >5mm -19.7% (P=.419) and IPSS: -32% and -22.5% (P=.202), respectively. Urgency, urge incontinence, and nocturia sub-scores were decreased in both groups, -26.3% and -27.4% (P=.690), 53.3% and 46.2% (P=.916), and 20.8% and 15.4% (P=.958). Effects were maintained at 12weeks. We found no significant improvement in the frequency sub-score in either group. One patient stopped medication because of intolerable hypertension. Most frequent adverse event was increased residual urine (≥50mL higher than baseline), IPP ≤5mm 9.2% and IPP >5mm 5.1% (P=.707), but no case had acute urinary retention. Mirabegron is an effective drug to treat male OAB regardless of IPP grade.