A Study to Evaluate the Efficacy and Safety of Mirabegron Compared to Solifenacin in Patients With Overactive Bladder Who Were Previously Treated With Another Medicine But Were Not Satisfied With That Treatment.

Inclusion Criteria: * Subject is willing and able to complete the micturition diary and questionnaires correctly * Subject has symptoms of OAB (urinary frequency and urgency with or without urgency incontinence) for at least 3 months * Subject is currently or has previously received at least one antimuscarinic agent intended to treat their OAB. The last antimuscarinic must have been taken for at least 4 weeks and taken within 6 months prior to the Screening Visit Exclusion Criteria: * Female subject is breastfeeding, pregnant, intends to become pregnant during the study, or of childbearing potential is sexually active and not practicing a highly reliable method of birth control * Subject has neurogenic bladder * Subject has significant stress incontinence or mixed stress/urgency incontinence where stress is the predominant factor as determined by the investigator (for female subjects confirmed by a cough provocation test) * Subject has an indwelling catheter or practices intermittent self-catheterization * Subject has diabetic neuropathy * Subject has evidence of a symptomatic urinary tract infection, chronic inflammation such as interstitial cystitis, bladder stones, previous pelvic radiation therapy or previous or current malignant disease of the pelvic organs * Subject has uncontrolled narrow angle glaucoma, urinary or gastric retention, severe ulcerative colitis, toxic megacolon, myasthenia gravis or any other medical condition which makes the use of anticholinergics c…