Background
Non-neurogenic overactive bladder (OAB) affects 7%-27% of men and 9%-43% of women, and symptoms cause considerable negative impact on quality of life. The American Urological Association has published a new guideline regarding diagnosis and treatment of OAB.
Conclusions
Overactive bladder is defined as urinary urgency (with or without urge incontinence) in the absence of urinary tract infection or other obvious pathology. Frequency and nocturia may be other cardinal features of OAB. Symptoms of OAB (particularly incontinence) significantly affect patients’ daily activities, and successful treatment of OAB symptoms has been shown to improve quality of life.
Dr. Alice Alexander
The AUA guidelines are based on a systematic review conducted under the auspices of the Agency for Healthcare Research and Quality, with the addition of several studies that focused on men with overactive bladder (who were excluded from the initial AHRQ review). There were insufficient studies to provide an evidence base for diagnosis, but there were numerous randomized controlled trials regarding treatments for OAB. The chief limitation of these trials is that the follow-up periods were generally short (less than 12 weeks).
The first-line treatment for OAB is behavioral therapy, as it may have benefits and has essentially no risks. These treatments require active participation on the part of the patient. Most of the available literature focuses on the outcome of incontinence, and typical mean improvements in trials of behavioral interventions range from 50%-80% reduction in episodes of incontinence. Based on limited literature, no single type of behavioral therapy appears to be superior to any other.
Antimuscarinic drugs are the only approved pharmacologic treatment for OAB. Available agents include darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine, and trospium. There is no evidence of differential efficacy between the above antimuscarinics, but there are different side effect profiles for each drug.
Most studies evaluating side effects looked at oxybutynin vs. tolterodine; dry mouth and constipation were more likely with oxybutynin than with tolterodine. Extended-release oral formulations cause less dry mouth than immediate-release oral formulations, and transdermal oxybutynin may cause less dry mouth than oral formulations.
Sacral neuromodulation, also known as sacral nerve stimulation (SNS), may benefit patients with very severe OAB symptoms who have been refractory to drug and behavioral therapy. Adverse events are relatively frequent – surgical revision rates are as high as 30%. Patients must comply with the treatment protocol, because benefits are maintained only as long as the device is being used appropriately. Placement of a SNS system means that diagnostic MRIs are contraindicated thereafter.
Peripheral tibial nerve stimulation (PTNS) may also benefit patients with moderately severe incontinence; patients must be able to comply with frequent office visits (once weekly for 12 weeks in the most common protocol). Follow-up durations in most studies of PTNS were relatively short.
In January 2013, the Food and Drug Administration approved intradetrusor onabotulinumtoxinA (Botox) injections for patients with overactive bladder who have contraindications to or don’t respond to anticholinergics.
These injections can improve symptoms, but the rates of urinary retention are very high. Patients may need to have postvoid residuals measured periodically and may have to perform self-catheterization for long periods.
Implementation
OAB is a clinical diagnosis: A history, physical exam, and urinalysis should be performed as part of the initial workup. A postvoid residual should be checked in a man who is being considered for antimuscarinic therapy. Urodynamics, cystoscopy, and ultrasound of the kidneys and/or bladder are not necessary in the initial workup of the patient with uncomplicated OAB.
It is important to educate patients about what is normal regarding bladder function. Regarding nocturia in particular, elderly patients can expect to have more of their urine output at night. And other factors, such as sleep problems, may contribute to nocturia. It is also important to distinguish frequency related to OAB from frequency related to polydipsia/polyuria.
Behavioral therapy is probably at least as efficacious as antimuscarinics, but it does not expose patients to the risks of drug therapy. Therefore, it is first-line for the treatment of OAB. Changing voiding habits, with delayed voiding and with bladder training, may modify bladder function. Pelvic-floor muscle training may also be helpful. Weight loss, fluid management, and reducing caffeine intake may also significantly reduce OAB symptoms.
Antimuscarinic therapy is second-line treatment for OAB. Oral antimuscarinics are effective in reducing frequency, urgency, and incontinence. But they have non–life-threatening side effects, including dry mouth, dry eyes, urinary retention, and constipation. Contraindications to antimuscarinic therapy include narrow-angle glaucoma, impaired gastric emptying, and a history of urinary retention. Antimuscarinics have not been well studied in the frail elderly; they may cause cognitive side effects and should be used with caution.