Prescription pattern of oxybutynin ER in patients with overactive bladder in real life practice: A multicentre, open-label, prospective observational study

Aims of study: To investigate the prescription pattern and dose distribution of the antimuscarinic agent oxybutynin extended release (ER) in patients with overactive bladder (OAB) in actual clinical practice. Materials and methods: In this multicentre, prospective, observational, flexible-dosing study, the dosage of oxybutynin ER for each patient was adjusted after discussions of efficacy and tolerability between doctor and patient, over a 12 week treatment period. Efficacy was measured by administering the Primary OAB Symptom Questionnaire (POSQ) before and after treatment. Patients were also administered, the patient perception of treatment benefit (PPTB) questionnaire at the end of the study. Adverse events (AE) were documented at each study visit. Results: Of the 809 patients enrolled, 590 (73.2%) continued to take study medication for 12 weeks. Most patients were prescribed 5 (24.2%) or 10 (68.8%) mg/day oxybutynin ER at the start of treatment. Most were also prescribed 5 (19.1%) or 10 (67.4%) mg/day at the end of treatment, with a dose escalation rate of 14.9%. All OAB symptoms evaluated by the POSQ were improved; 94.1% of patients reported benefits from treatment and 89.3% were satisfied. Independent predictive factors for discontinuation were female, younger age (age ≤ 65), obesity (BMI ≥ 25), severe symptoms (USS, Gr. 5) and larger numbers of other co-medications. Conclusions: Most patients were prescribed 5-10 mg/day oxybutynin ER as both starting and maintenance doses, with a dose escalation rate of only 14.9%. Prescription of > 10 mg/day oxybutynin ER was not frequent in real life practice.