Study design, materials and methods
Between July 2009 and January 2018, all women with OAB visiting a medical center for evaluation were reviewed. The classification of OAB-wet or OAB-dry is based on the record of three-day bladder diary of each patient. The diagnosis of OAB in each patient was based on the presence of at least one episode of urgency in her three-day bladder diary and with the absence of stress urinary incontinence. The presence of at least one episode of urgency associated incontinence was defined to be OAB-wet, otherwise, OAB-dry.
Results
A total of 1,071 women with OAB, including 203 (19.0%) OAB-wet and 868 (81.0%) OAB-dry women were included in this study. There was a trend of an increase in the rate of OAB-wet with aging, especially after the age period of 61-70 (Table 1).
Receiver operating characteristic curve analysis revealed age ≥ 64 year-old is an optimal cut-off value to predict OAB-wet (sensitivity = 52.2%, specificity = 68.0%; area = 0.61, 95% CI = 0.56 to 0.65). The rates of OAB-wet in women < 64 year-old and ≥ 64 year-old were 14.1% (97/687) and 27.6% (106/384), respectively (P < 0.001).
In addition, OAB-wet was associated with a higher Overactive Bladder Symptom Scores (OABSS), Urgency Severity Scales (USS), Urogenital Distress Inventory (UDI-6) score, pad weight and urgency episodes; and a lower maximum urethral closure pressure (MUCP) and daytime frequency episodes, compared with OAB-dry (Table 2).
Besides, OAB associated variables, such as OABSS, USS and UDI-6, voided volume, the volume at strong desire to void and nocturia episodes, deteriorated with aging (Table 2).
Interpretation of results
Age more than 65 year-old is usually defined as old age. OAB associated variables deteriorated with aging, especially after 64-year-old. Thus, it is prudent to assess old age women with OAB whether having concomitant urgency incontinence. In addition, poor urethral sphincter function might play a role in the pathophysiology of OAB-wet.