Overactive Bladder

Introduction

Overactive bladder (OAB) is a syndrome characterised by symptoms of urgency, with or without urgency incontinence, usually with increased daytime frequency and nocturia (increased night-time urination). The term OAB can only be used if there is no proven infection or other causative pathology.

OAB affects about 12% of both men and women. The incidence increases with advancing age and affects between 70-80% of people by the age of 80. More women than men exhibit incontinence, but, overall, 33% of patients have OAB with urgency incontinence (“OAB wet”), while 66% have OAB without urgency incontinence (“OAB dry”). OAB is a bothersome condition that negatively affects quality of life and can lead to social isolation. OAB also has significant psychological and financial consequences and may be associated with increased morbidity and mortality in the elderly. For instance, older individuals may need to get up more frequently at night increasing their risk of falls.

Symptoms

The symptoms of OAB are suggestive of detrusor (bladder muscle) overactivity but can be due to other forms of urinary/voiding dysfunction. The symptom of urgency is the most bothersome and drives the other OAB symptoms.

• Urgency is the sudden, compelling desire to pass urine which is difficult to defer.
• Urgency urinary incontinence is the complaint of involuntary leakage of urine that is accompanied by or immediately preceded by urgency.
• Frequency denotes voiding too often during waking hours. In clinical trials, this has generally been defined as urinating more than 8 times in a 24 hour period. The new ICS definition does not specify a particular number of voids, as an increase in the daytime frequency is a subjective matter that can be confirmed by a bladder diary. The key question when assessing urinary frequency is the degree of bother to the patient, as there is no scientifically proven definition.
• **Nocturia **refers to the need to awaken to void one or more times during sleep.
• Detrusor overactivity (DO) is a diagnosis made after urodynamics, clinical studies of bladder function. Such testing demonstrates involuntary detrusor contractions during bladder filling. While OAB is a clinical diagnosis, DO occurring spontaneously or by provocation, is a urodynamic diagnosis that may or may not be associated with OAB.
  The majority of people with OAB are thought to have detrusor overactivity (DO): 69% of men and 44% of women with urgency but no incontinence have DO, while 90% of men and 58% of women with urgency urinary incontinence have DO. Since Overactive Bladder Syndrome is a clinical diagnosis, urodynamic testing is not required to establish the diagnosis.

Assessment

The clinical diagnosis of OAB is based on a careful history and physical examination. The key symptom is urinary urgency which the patients may describe in various ways, the key feature being an inability to hold their urine long enough to make it to the lavatory. The diagnosis is supplemented by the use of a bladder diary or frequency-volume chart. It documents how frequently a patient voids over a 24-72 hour period. The bladder diary may show increased daytime frequency and nocturia with small voided volumes and incontinence episodes in between. Urinalysis with culture as indicated is necessary to rule out infection and if blood is present in the urine, the patient must be evaluated for bladder cancer.

Treatment

Lifestyle modifications, behavioural therapy and pharmacotherapy in the form of antimuscarinics or B3-agonists are the mainstays of treatment.
About 50% of patients gain satisfactory benefit from lifestyle modifications when combined with behavioural therapy such as bladder retraining and pelvic floor muscle rehabilitation. Lifestyle modifications and behavioural therapy involve avoiding caffeinated beverages and other bladder irritants, restricting fluid intake at night, changing the time of administration of diuretics and training the bladder to hold for a longer period of time. Individuals suffering from OAB should attempt these before seeking further interventions.

Antimuscarinic agents are often effective for the treatment of OAB. A number of approved medications are available: oxybutynin, tolterodine, fesoterodine, trospium, solifenacin, darifenacin and propiverine. More recently, mirabegron, the first of a new class of medication for OAB, the beta-3 agonists, has come into use. If medication is not tolerated or is ineffective, minimally invasive procedures such as injection of botulinum toxin A into the bladder wall, posterior tibial nerve stimulation (transcutaneous electrical current directed via needle just above the ankle), or sacral neuromodulation (spinal implant) are available.

If the minimally invasive therapies fail, surgical urinary diversion may be necessary as for neurogenic detrusor overactivity. (Please see fact sheet on Neurogenic Bladder.) Surgery for detrusor overactivity should be reserved only for patients for whom all less nvasive treatment modalities have failed, since all surgical procedures entail greater potential for complications.

Conclusion

Overactive bladder is a highly prevalent condition associated with impairments in many domains of QOL. It is effectivelty treated by conversative, pharmacological or minimally invasive therapies.

Suggested reading

1. Abrams P, Cardozo L, Fall M, et al. The standardisation of terminology of lower urinary tract function: report from the Standardisation Sub-committee of the International Continence Society. Neurourol Urodyn 2002; 21(2): 167-178.
2. Andersson KE, Chapple CR, Cardozo L, et al. Pharmacological treatment of urinary incontinence. In: Abrams P, Cardozo L, Khoury S, Wein A, editors. Incontinence. 4th International Consultation on Incontinence ed. Paris: Health Publication Ltd.; 2009. PP. 631-700.
3. Nygaard I. Clinical practice. Idiopathic urgency urinary incontinence. N Engl J Med. 2010;363(12):1156-62.
4. Marinkovic SP, Rovner ES, Moldwin RM, et al. The management of overactive bladder syndrome. BMJ 2012;344:e2365. Review.