OBJECTIVES: To explore the ability (validity) of the OAB-V8 screening scale to predict changes in patient’s HRQoL and severity of symptom bother (SB) in subjects with symptomatic OAB treated with antimuscarinic drugs in daily practice in clinics of Urology. METHODS: Patients, both genders, >18 years, with symptomatic OAB [score >8 in OAB-V8 scale] and able to understand and fill-in PRO instruments written in Spanish were enrolled in this study. The culturally adapted and validated Spanish version of OABq-SF was administered twice 3 months apart to patients recruited consecutively at clinics of Urology all over the country and who were prescribed a treatment with an antimuscarinic drug according to usual practice. Patients were compared in the OABq-SF: SB and HRQoL scorings. To test the predictive validity of the OAB-V8 scale, baseline scores were included in multivariate regression models along with age, symptoms duration, age at the initiation of symptoms, body mass index, and generic HRQoL (assessed with EQ-5D) as covariates to predict changes in OABq-SF dimensions from baseline to follow-up at 3-months period. RESULTS: The study enrolled 246 OAB symptomatic patients (mean age 57.7 years, 67% women, 99% Caucasian, 37% active workers, 36% primary schooling). OAB-V8 scores significantly correlated (Pearson´s r coefficient) with OABq-SF domains; +0.790 and -0.659 for SB and HRQoL domains, respectively (p<0.001 in both cases) indicating a possible linear relation. Multivariate regression models showed OAB-V8 baseline score being able to predict changes in both domains of the OABq-SF; R2 =0.212 and 0.162 in severity of SB and HRQoL, respectively. OAB-V8 coefficients were significant in the two models with β coefficients of 0.421 (p<0.001) and 0.340 (p<0.001), respectively.    CONCLUSIONS: The OAB-V8 scale provided evidence of predictive validity of self-assessment quality-of-life and severity of symptoms bother changes in patient with OAB treated with antimuscarinic drugs in routine medical practice.