Study to Evaluate the Efficacy, Safety, and Tolerability of Mirabegron in Older Adult Subjects With Overactive Bladder (OAB)

Inclusion Criteria assessed at Visit 1 (Screening): * Subject is willing and able to complete the micturition diary and questionnaires correctly. * Subject has symptoms of wet overactive bladder (OAB) (urinary frequency and urgency with incontinence) for greater than or equal to 3 months prior to Screening. * Subject agrees not to participate in another interventional study from the time of screening until the final study visit. Inclusion Criteria assessed after placebo run-in period at Visit 3 (Baseline): * Subject continues to meet all inclusion criteria of Visit 1. * Subjects must experience at least one incontinence episode in the placebo run-in period based on the 3-day micturition diary. * Subject must experience at least 3 episodes of urgency (grade 3 or 4) based on the 3-day micturition diary. * Subject must experience an average of greater than or equal to 8 micturitions/day based on the 3-day micturition diary. Exclusion Criteria assessed at Visit 1 (Screening): * Subject has ongoing symptoms suggestive of bladder outlet obstruction (BOO) or history of BOO that is currently not well controlled. * Subject has Post-Void Residual Volume (PVR) greater than 150 mL. * Subject has neurogenic bladder or neurological dysfunction or injury which could affect the lower urinary tract or nerve supply. * Subject has significant stress incontinence or mixed stress/urgency incontinence where stress is the predominant factor as determined by the Investigator (for female subject…