Two distinct entities: Bladder oversensitivity and detrusor overactivity

We read Dr. Chen's article entitled “Are patients with bladder oversensitivity different from those with urodynamically proven detrusor overactivity in female overactive bladder syndrome?” with interest. Dr. Chen and colleagues prospectively evaluated 205 patients with overactive bladder syndrome (OAB) by urodynamic study to compare the differences between clinical characteristics and urodynamic perception volume with filling cystometry set at a relatively lower filling rate (20 ml/min). The authors found that the use of cut-off value of 127 ml in the item of first desire to void could provide an acceptable predictive value for detecting detrusor overactivity with a sensitivity of 70.6% and a specificity of 59.1%. We congratulated the success of publication of the authors. As shown by authors, clinical parameters in their study have already shown the significantly different patterns between bladder oversensitivity and detrusor overactivity. Nocturia is frequently found in women with bladder oversensitivity than that with detrusor overactivity (48.6% vs. 29.6%, p < 0.001). By contrast, urgency and urgent incontinence is often found in women with detrusor overactivity than that with bladder oversensitivity (38.5% vs. 14.3%, p < 0.001), and additionally, frequency and urgency occurred in nearly all women with bladder oversensitivity compared to that in the third-fourths with detrusor overactivity (97.1% vs. 77.8%, p < 0.001). Although the different clinical presentations of symptoms between bladder oversensitivity and detrusor overactivity are found, it is sometimes difficult for a clinician to distinguish each other. Therefore, with an aid of objective urodynamic study, it may become much easier. We congratulated the authors' success to provide a relatively good reference to distinguish two distinct entities. The authors found the statistically significant difference of first desire to void between two (117.5 ± 21.7 ml vs. 135.2 ± 22.9 ml, p < 0.001). Furthermore, the authors used a receiver operating characteristics curve to detect the cut-off value of 127 ml (0.702, 95% confidence interval 0.629e0.779) which can be used to distinguish bladder oversensitivity from detrusor overactivity. Although it is promising, there are some uncertainties which need discussion. First, the cut-off value to distinguish bladder oversensitivity from detrusor overactivity may be questionable. However, it may be not practical, since both bladder oversensitivity and