Diagnosing, Treating Refractory OAB
Patients with refractory OAB most likely represent a minority of the total OAB population.
Idiopathic overactive bladder (OAB) is a common condition in the United States, with a prevalence of 16% for men and 16.9% for women (World J Urol. 2003;20:327-336). OAB is costly, with related expenditures for 2000 estimated at more than $26 billion.
Defined by the International Continence Society (ICS) as urgency with or without urge incontinence, OAB is usually accompanied by nocturia and frequency in the absence of explanatory pathology. Urgency of urination, which acts as the primary driving force for the OAB patient, is defined by the ICS as a “sudden compelling desire to pass urine that is difficult to defer.”
In contrast to 20 years ago, multiple treatment options now exist. They include behavioral modification, timed voiding, pelvic floor exercises, and anticholinergic medications. Patients with refractory OAB have, by definition, failed these first-line treatment modalities; options for these patients include neuromodulation and off-label use of botulinum toxin A.
Despite the high prevalence of OAB, the majority of patients do not require intervention, and many may not seek treatment. This is likely the result of variability in patients' perception of bother and impact on quality of life (QoL). The criteria for treatment are debatable but usually are determined when OAB symptoms begin to affect QoL.
The epidemiology of the refractory OAB patient is unknown, but these individuals most likely represent a minority of the total OAB population. Many patients may be prematurely labeled as having refractory OAB after only a modest attempt at medical or behavioral treatments.
Therefore, true population studies of the refractory OAB patient are difficult to perform accurately. Inability to consistently identify and classify this population has severely limited our understanding of the natural history of the OAB patient (J Urol. 2003;169:843-848). Adding further complexity is the fact that male and female OAB can have different causes.
OAB affects QoL in all patients. Several studies have demonstrated this, using both specific and nonspecific health-perception instruments (Short Form-36 and Incontinence-QoL). Patients with OAB have more depression and depression-related symptoms than controls without OAB (Urol Clin North Am. 2006;33:433-438). Sleep disturbances may be related to the nocturia component of the OAB symptom complex.
Women with OAB have a 26% greater risk of fall, accompanied by a 34% increased risk of bone fractures; this risk was even higher for those who had daily leakage episodes. There also is evidence that OAB patients may have more skin and urinary tract infections, and that these decrease in number after OAB treatment. Sexual dysfunction is common in both male and female OAB patients.
Assessment with the Female Sexual Function Index showed negative effects on orgasm, lubrication, sexual desire, and satisfaction (J Sex Med. 2008;5:1418-1423).
For men, lower urinary tract symptoms have been shown to be an independent risk factor for erectile dysfunction, and successful treatment of these symptoms may help improve sexual function (Curr Med Res Opin. 2006;22:2497-2506). Last, an increase in bowel complaints has been observed in 58.6% of female patients with refractory OAB (Neurourol Urodyn. 2007;26:19-28).
Evaluation and diagnosis
A comprehensive history is essential in all patients whose complaints are consistent with OAB. If the chief complaint has a major pain component, a diagnosis of interstitial cystitis warrants consideration. Details determined from careful history-taking (comorbid conditions, such as diabetes, prior urologic surgeries, history of urethral instrumentation, or sexually transmitted diseases) are very important for an accurate diagnosis.
For example, if the problem is relatively acute, attention should be focused on recently prescribed medications, such as diuretics, that could be causing the problem. Further, if the patient has a history of tobacco use, bladder cancer is a strong consideration. Discussion of caffeine, alcohol, and general daily fluid intake may also prove revealing.
A thorough physical examination is crucial and should include a detailed pelvic examination. The examiner should look for signs of prolapse and leakage with cough to help rule out potentially coexistent stress incontinence (mixed incontinence). Careful palpation of the urethra will detect masses or urethral diverticula. The levator muscles should be examined, with special attention given to point tenderness and spasm, both of which may indicate pelvic floor dysfunction.
Male patients require a genital exam as well, and the prostate should be palpated for masses or signs of benign prostatic hyperplasia. In all patients, a focused neurologic exam is needed to assess both sensation and rectal tone. The lower back should be examined for signs of dimpling or hair tuft, which would suggest myelodysplasia/spina bifida.
One of the most important diagnostic tools remains the three-day fluid and voiding diary. The potentially important information gleaned from this tool includes fluid intake and output, times of fluid intake and output, functional bladder capacity, and documentation of leakage and type of leakage.