How durable is the effect of mirabegron in successfully-treated overactive bladder patients? Analysis of a multicentre study.

ABSTRACT

OBJECTIVE: Many clinical studies indicate that pharmacologic treatment of overactive bladder (OAB) is considered effective and safe, but in real clinical practice a substantial proportion of patients discontinues the treatment. The reason for discontinuing the treatment most frequently reported is lack of efficacy and/or side effects. A further significant proportion of patients reports that they stopped the treatment because the symptoms disappeared or were resolved. This β3 agonist seems to be crucial in providing comparable efficacy in the OAB treatment and better tolerance in comparison with anticholinergics. Our aim was to investigate the durability of the mirabegron effect in successfully treated OAB patients and to understand more fully what prompts patients to return to the medication. Is this merely a subjective decision, or is it based on objective worsening of the symptoms? DESIGN: Analysis of multicentre prospective study. SETTINGS Gynaecology and Obstetric Department First Faculty of Medicine, Charles University and General University Hospital, Prague. METHODS: This is an analysis of longitudinal multicentre study of OAB mirabegron treatment persistence. After continuing mirabegron treatment for more than 18 months patients were assessed by bladder diary and specific questionnaires. Patients with a UB-VAS score (Urgency Bother Visual Analogue Scale) of 50 or less were asked to stop the mirabegron treatment and restart the treatment any time later if they felt the need. Patients recorded the date of return to medication; they kept a daily bladder diary and filled in the same questionnaires as at the time of medication discontinuation. We provide a comparison of symptoms at the time of mirabegron discontinuation and at the time of mirabegron medication restart. RESULTS: 206 patients entered the study. 176 females (85%) and 30 males (15%) with mean age 62.9 ± 12.43, BMI ranging from 16.6 to 48.0 (mean 27.2 ± 4.96). After 18 months 126 patients were persisting with mirabegron treatment. 89 patients had UB-VAS score 50 (89 of 126 patients, i.e. 71%). Those patients were asked to stop the treatment. From the eligible group of 89 patients, 19 patients (21%) were unwilling to stop the treatment and were therefore excluded. There were no significant differences in bladder diary and QoL characteristics between patients who were unwilling to discontinue the treatment and patients who did stop taking the medication. The group who stopping treatment comprised 70 patients. At the time of last follow-up 22 patients (31%) had not restarted the medication, with mean follow-up of 122.6 days. Therapy was restarted by 48 patients (i.e. 69% of 70). The mean time without treatment was 48 days (± 32.0 days), median 53 days. There was significant worsening of OAB symptoms and subjective bother at the time of restarting the medication. CONCLUSION: Subjective bother based on increase number of frequency, urgency, and nycturia causes patients with positive experience to return to mirabegron treatment. Most patients with successfully-treated symptoms of OAB who discontinue treatment can only do so temporarily. A worsening of the symptoms occurs rather rapidly, because 69% of patients with OAB symptoms successfully treated with mirabegron (UB-VAS 50) are unable to discontinue taking the medication for more than two months.