OBJECTIVES: To assess the effect of individual International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes on database estimates of overactive bladder (OAB) in the absence of a specific OAB ICD-9-CM code. METHODS: ICD-9-CM codes used to define OAB were identified from a review of published claims database studies. OAB prevalence and patient characteristics were evaluated for each code using 2015 OptumHealth claims data. Prevalence was calculated among all subjects in the data with insurance eligibility. The share of patients with a medical claim for each code was counted overall, and compared between visits to urologists and all other healthcare providers. Patient clinical and demographic characteristics and oral OAB pharmacologic treatment rates were measured for each sample. RESULTS: Fourteen studies were reviewed, yielding 27 distinct ICD-9-CM codes used to identify OAB patients. A total of