Overactive bladder (OAB): A symptom in search of a disease - Its relationship to specific lower urinary tract symptoms and conditions.

Background: The ICCS defines OAB by the subjective symptom of urgency; detrusor overactivity (DO) is only implied. While no other symptom is required, OAB can also be associated with urinary frequency, decreased functional bladder capacity, and incontinence.

Objective: We sought to determine how often these associated findings occur in OAB and what if any uroflow/EMG-defined conditions are found to be associated with it.

Methods: The charts of 548 children (231M, 318F; mean age 9.0 years, range 3-20) who presented sequentially with urgency (OAB), over a period of 2 years, were reviewed paying particular attention to whether or not there was a history of frequency and/or daytime incontinence in addition to the urgency. All patients had been previously diagnosed with one of the following four lower urinary tract (LUT) conditions based on specific uroflow/EMG findings: 1. dysfunctional voiding (DV; active pelvic floor EMG during voiding); 2. idiopathic detrusor overactivity disorder (IDOD; OAB with a short EMG lag time (<2 s), and quiet pelvic floor EMG during voiding); 3. detrusor underutilization disorder (DUD; willful infrequent voiding with %EBC >125%, quiet EMG during voiding); and 4. primary bladder neck dysfunction (PBND; prolonged EMG lag time (>6 s), quiet EMG during voiding, and depressed uroflow curve). Mean %EBC was compared between patients with urgency alone and those with urgency plus other symptoms. Any association with gender was analyzed.

Results: Urgency was accompanied by either frequency or daytime incontinence in 91% of the children (summary Table). Daytime incontinence was reported in 398 (72.6%) and frequency in 268 (48.9%). Mean %EBC was 80.9. Females were more likely to report daytime incontinence (76.7% vs. 66.7%, p = 0.02) and frequency was found more often in males (63.6% vs. 38.1%, p < 0.001). %EBC was less in males (70.0 vs. 88.8, p < 0.001). The majority of patients with urgency were diagnosed with IDOD (62%), while 15% had DV, 5% PBND, 3% DUD, and in 15%, the uroflow/EMG was not diagnostic.

Conclusions: %EBC was usually normal or mildly increased in OAB when urgency is the only symptom but significantly decreases with each additional LUTS. OAB is more common in girls and they tend to have a lower incidence of frequency, more incontinence, and >%EBC than boys. Because urgency in an anatomically and neurologically normal child is the only required criterion for diagnosing OAB, it must be realized that OAB can be associated with any of a number of objectively defined LUT conditions. Thus OAB appears to be a symptom, not a condition, that is often associated with other symptoms.