Overactive bladder

Synonym: detrusor instability

See also the separate articles Urinary incontinence and Voiding difficulties.

What is overactive bladder?

Overactive bladder (OAB) is also known as overactive bladder syndrome. Overactive bladder syndrome is defined as “urinary urgency, usually accompanied by frequency and nocturia, with or without urinary incontinence, in the absence of UTI or other obvious pathology”.¹ Overactive bladder is a chronic condition that can have debilitating effects on quality of life. The hallmark urodynamic feature is detrusor overactivity but the diagnosis of OAB is exclusively based on symptoms.

Strictly speaking, the term overactive bladder should be confined to cases where the condition is secondary to a known cause, whilst overactive bladder syndrome should be used in cases which are idiopathic. In practice the term is often used interchangeably. OAB can have a significant impact on quality of life.²

• OAB is the second most common cause of female urinary incontinence (stress incontinence is the most common).

• The EPidemiology of InContinence (EPIC) study was a cross-sectional telephone survey of adults
  conducted in five countries and demonstrated an overall prevalence of OAB symptoms of 11.8% (10.8% in men
  and 12.8% in women).¹

• The prevalence of OAB increases with age.²

• OAB may be associated with Parkinson's disease, spinal cord injury, diabetic neuropathy, multiple sclerosis, dementia or stroke; however, most cases have no specific cause.

• Several studies have highlighted a positive association between metabolic syndrome and OAB, with female predisposition.³⁴

• In men, urge incontinence may be due to neurological disease or an enlarged prostate gland (benign prostatic hypertrophy or prostate cancer).

Overactive bladder symptoms include a sudden urge to pass urine that is very difficult to delay and may be associated with leakage. Other features include:

• Frequency of micturition.

• Nocturia.

• Abdominal discomfort.

• Urge incontinence (more common in women).

There are no specific physical signs and the diagnosis is usually made from the symptoms (as assessed by keeping a bladder diary for between 3-7 days).¹

• Stress incontinence.

• Functional incontinence.

• Overflow incontinence.

• Urinary fistula.

• Enuresis.

• Urinary tract infection.

• Diabetes.

• Bladder cancer.

• Bladder stones.

• Urine dipstick analysis and midstream urine specimen should be sent to the laboratory in order to rule out urinary tract infection.

• A post-void residual urine collection is useful.

• Investigations to consider differential diagnosis - eg, blood tests for renal function, electrolytes, calcium, fasting glucose.

• Urodynamic studies show involuntary contraction of the bladder during filling. Whilst this is a gold standard test for detrusor overactivity, it should not be requested routinely.⁶

• Depending on the presentation, ultrasound of the renal tract and cystoscopy may be required. However, neither is recommended routinely by the European Association of Urology.⁶

Initial management in primary care⁷

The following may be helpful, both for men and for women.

• Lifestyle changes:

  • Trial of reduction in caffeine intake.

  • Modification of high or low fluid intake. Some patients may cut back on the amount that they drink so that the bladder does not fill so quickly.

  • However, this can make symptoms worse, as the urine becomes more concentrated, which may irritate the bladder muscle. Patients should aim to drink normal quantities of fluid per day (about two litres).

  • If body mass index is over 30, advise the patient to lose weight.

• Incontinence management strategies:

  • Patients who present with incontinence symptoms should be advised regarding potential strategies used to manage incontinence (eg, liners, pads, pants and slips, barrier creams, external catheters, absorbent washable protective briefs or underwear) and to mitigate the impact of leaking on QoL.⁵

• Bladder training :⁸

  • This is first-line treatment and should be for a minimum of six weeks.

  • It typically involves pelvic muscle training, scheduled voiding intervals with stepped increases and suppression of urge with distraction or relaxation techniques .

  • A 2023 Cochrane systematic review showed that most of the current evidence was low or very-low certainty of the efficacy of the treatment.⁹

• Drug treatment:¹⁰

  • Anticholinergic drugs: anticholinergics (antimuscarinic drugs) - eg, oxybutynin, propiverine, tolterodine, darifenacin, solifenacin, fesoterodine, trospium chloride - have a direct relaxant effect on urinary smooth muscle. They reduce involuntary detrusor contractions and increase bladder capacity. A 2023 Cochrane systematic review (47106 participants) showed the use of anticholinergic drugs results in important but modest improvements in symptoms compared with placebo treatment.¹¹ In addition, recent studies suggest that this is generally associated with only modest improvement in quality of life. Adverse effects were higher with all anticholinergics compared with placebo. Withdrawals due to adverse effects were also higher for all anticholinergics except tolterodine. It is not known whether any benefits of anticholinergics are sustained during long-term treatment or after treatment stops. There is no evidence of a clinically important difference in efficacy between antimuscarinic drugs. Immediate-release non-proprietary oxybutynin is the most cost-effective of the available options, although European guidelines suggest extended-release formulations are associated with fewer side-effects (eg, dry mouth).⁶ Oxybutynin may be started if bladder training is not effective. It may also be used in conjunction with bladder training. Do not use in the frail or elderly who may be at risk of sudden deterioration in physical or mental health.¹²

  • The efficacy and side-effects of tolterodine are comparable to those of modified-release oxybutynin. When choosing between oral immediate-release oxybutynin or tolterodine, tolterodine may be preferable because of the reduced risk of dry mouth. As with oxybutynin, extended-release preparations of tolterodine might be preferred to immediate-release preparations because there is less risk of dry mouth.¹³

  • Tolterodine is as effective in reducing leakage and other symptoms of OAB in patients with mixed incontinence as it is in patients with urge incontinence alone.¹⁴

  • If immediate-release oxybutynin is not well tolerated, darifenacin, solifenacin, tolterodine, propiverine, trospium or an extended-release or transdermal formulation of oxybutynin should be considered as alternatives.⁷

  • Intravaginal oestrogens: these can be used to treat OAB syndrome in postmenopausal women who have vaginal atrophy.

  • Mirabegron and vibegron are agonists of beta-3 receptors in detrusor smooth muscle, designed to promote detrusor relaxation. They are recommended for people in whom antimuscarinic drugs are contra-indicated or clinically ineffective, or who have unacceptable side-effects.¹⁵ It is contra-indicated in patients with severe uncontrolled hypertension.¹⁶

When to refer⁷

• Patients on anticholinergic drugs should be reviewed after four-weeks if there is no benefit from current treatment, and the dosage altered or another drug in the group tried.

• A secondary care referral should be considered for patients who fail to respond to drug treatment after three months or who do not wish for drug treatment.

• Patients who are stable on drug treatment should be reviewed annually (or six-monthly if aged over 75).

Management options offered in secondary care^{1 7}

Before embarking on invasive treatments, patients who fail to respond to conservative measures should have urodynamic studies to ensure that their symptoms are due to detrusor overactivity. Involvement of a multidisciplinary team (MDT) is recommended.

• Botulinum toxin A:

  • Injection of the bladder wall with botulinum toxin A is the first-line invasive option. It may be used if there is idiopathic OAB that has not responded to conservative treatment. The patient must be prepared to perform intermittent catheterisation if the effects wear off between injections. Urinary tract infections are a recognised risk. The duration is variable. More research is required to determine the long-term risks and benefits.

• Nerve stimulation:¹⁷

  • Sacral nerve stimulation is effective in treating symptoms of OAB, including urinary urge incontinence, urgency and frequency in patients who do not respond to botulinum toxin A.

  • Percutaneous posterior tibial nerve stimulation (PTNS) is also effective in reducing symptoms in the short term and medium term for patients with OAB syndrome and should be offered to patients who do not want the first- or second-line options.

• Surgical treatment:

  • Surgery is only indicated for intractable and severe idiopathic OAB. Augmentation cystoplasty is the most frequently performed surgical procedure for severe urge incontinence.

  • In patients whose condition is refractory to non-surgical treatment, open augmentation cystoplasty or laparoscopic augmentation cystoplasty (including clam cystoplasty) are established procedures.¹⁸

May cause severe social difficulties, including undertaking shopping and attending meetings and therefore may also lead to social isolation and psychological difficulties.

Lifestyle changes combined with drug treatment are often effective, but shared decision-making and a patient-centred approach are recommended when improvement does not occur. Caution should be exercised when prescribing anticholinergic medicines long-term to older adults.