OBJECTIVES:  Antimuscarinic (AM) and β3 adrenergic receptor agonist medications (mirabegron) are commonly used to treat symptoms associated with OAB. Mirabegron is typically prescribed as a second line agent to AMs. The objective was to describe baseline characteristics including CV risk in OAB patients initiating treatment with either mirabegron or an AM, or those who were untreated. METHODS:  Integrated claims and electronic health records (EHR) of patients with OAB were examined. Index was the first date of treatment for AM or mirabegron between October 2012 and December 2014. Patients with12 months pre-index data, baseline blood pressure (BP) measurements, and no CV events within 30 days pre index were included. Untreated OAB cohort included patients without recorded OAB treatment. Index for untreated patients was the earliest date with their OAB related diagnosis within the same identification period. Unadjusted demographic and clinical characteristics, including CV risk factors, were compared across groups at index. RESULTS:  The study groups included 54,187 untreated patients, 10,311 AM patients, and 408 mirabegron patients. Compared to AM and untreated patients, mirabegron patients were older (mean age 70 years vs. 67 years AM and 60 years untreated). Males comprised 33.6% of mirabegron patients, 26.8% of AM patients, and 39.6% of untreated patients. Mirabegron patients were more likely to have had prior CV events >30 days pre index (17.2% vs. 14.3% for AM and 12.3% for untreated), and were more likely to have diabetes mellitus (42.2% vs. 34.8% for AM and 26.3% for untreated). Baseline BP and cholesterol were similar across groups. Concomitant medication use was highest in AM patients. CONCLUSIONS:  In a real world analysis, baseline CV risk differs between OAB patients receiving mirabegron versus antimuscarinics. Analysis using integrated claims and EHR data therefore require adequate bias reduction techniques for assessing CV risk in OAB populations.