First morning voided volume as a valuable tool for evaluating patients with overactive bladder

ObjectiveThis study aims to assess whether first morning voided volume (FMV) can be used as a tool to evaluate the symptom severity of patients with an overactive bladder (OAB).Materials and methodsWe prospectively recruited patients with OAB symptoms from January 2009 to April 2010. All the patients completed a 3-day frequency–volume chart, including the measure of FMV and the Overactive Bladder Symptom Score (OABSS) questionnaire. All patients underwent either conventional pressure-flow urodynamic study or videourodynamic study. We analyzed the correlation between FMV, urodynamic studies, and symptom severity.ResultsA total of 102 patients, including 43 men and 59 women, were recruited in the study. FMV was significantly correlated to the daily mean voided volume (p < 0.001) and cystometric capacity (p = 0.026). It was also negatively correlated to the subscores for daytime frequency (p = 0.013) and nighttime frequency (p < 0.001) on OABSS. However, no significant correlation was observed between FMV and the total score of OABSS. FMV showed a fair agreement with the maximum voided volume, which can predict small-volume bladders (kappa = 0.42 ± 0.08, p < 0.001), whereas the agreement between cystometric capacity and maximum voided volume was poor (kappa = 0.096 ± 0.05, p = 0.08).ConclusionIn patients with OAB, FMV can represent the severity of day- and nighttime frequencies. FMV was also shown to have a better ability in predicting small-volume bladders compared to the cystometric capacity. The measure of FMV may be helpful for patients who have poor compliance with regard to recording the frequency–volume chart.