Is estradiol (estrogen replacement therapy) associated with urinary incontinence?

Estrogen and Urinary Incontinence: The Relationship and Clinical Implications

Estrogen therapy is associated with an increased risk of urinary incontinence in postmenopausal women, particularly when administered systemically, and should not be used as a treatment for urinary incontinence. 1

Evidence on Estrogen and Urinary Incontinence

Systemic Estrogen Therapy

The Women's Health Initiative (WHI) provided high-quality evidence demonstrating that systemic estrogen therapy increases the risk of urinary incontinence:

• Combined oral hormone therapy (estrogen plus progestin) increased the risk of new-onset stress, urge, or mixed urinary incontinence (HR 1.39,95% CI 1.27-1.52) 1
• Oral estrogen alone showed an even higher risk (HR 1.53,95% CI 1.37-1.71) 1
• These symptoms persisted in a subsample of estrogen and progestin users at 3 years of follow-up 1

The 2012 USPSTF review confirmed that both hormone therapy regimens (estrogen alone and estrogen plus progestin) increase the risk for urinary incontinence 1.

Route of Administration Matters

The effect of estrogen on urinary incontinence appears to depend on the route of administration:

• Vaginal estrogen formulations may improve stress incontinence:

  • Vaginal estrogen tablets and ovules showed improvement in urinary incontinence compared to placebo 1
  • Vaginal estrogen tablets increased continence compared with placebo (NNTB 5,95% CI 3-12) 1

• Transdermal estrogen patches worsened both stress and any urinary incontinence 1

• Estradiol implants did not improve urinary incontinence compared to placebo 1

Combination Therapy

When estrogen is combined with other treatments:

• Low-quality evidence showed that intravaginal estriol plus pelvic floor muscle training (PFMT) more effectively achieved continence than intravaginal estriol alone (NNTB 1,95% CI 1-2) 1

• However, one small trial showed women were more likely to have improvement in incontinence with PFMT alone than with local estrogen therapy 2

Clinical Decision Algorithm

1. For postmenopausal women with urinary incontinence:

   • Do NOT prescribe systemic estrogen (oral or transdermal) to treat urinary incontinence
   • Systemic estrogen therapy worsens incontinence and should be avoided when incontinence is a concern

2. For postmenopausal women with vaginal atrophy AND urinary symptoms:

   • Consider vaginal estrogen formulations (tablets or ovules) which may improve stress incontinence
   • Monitor for improvement in symptoms

3. For women already on systemic HRT who develop incontinence:

   • Consider discontinuing systemic estrogen therapy if urinary incontinence is bothersome
   • Discuss alternative treatments for menopausal symptoms

4. First-line treatments for urinary incontinence should be:

   • Pelvic floor muscle training (more effective than estrogen therapy)
   • Weight loss and exercise in obese women (NNTB 4,95% CI 2-18) 1
   • Behavioral therapies

Common Pitfalls and Caveats

1. Conflicting historical data: Older studies suggested estrogen might improve incontinence, but large randomized trials have demonstrated the opposite for systemic therapy. The Women's Health Initiative provides the strongest evidence on this topic.

2. Route of administration confusion: The effects of estrogen on urinary incontinence vary significantly by route of administration. Systemic estrogen worsens incontinence, while vaginal estrogen may improve it in some cases.

3. Prescribing estrogen for incontinence: Despite evidence to the contrary, some clinicians still prescribe systemic estrogen for urinary incontinence. This practice should be avoided as it may worsen symptoms.

4. Ignoring other effective treatments: Non-hormonal approaches like pelvic floor muscle training, weight loss, and bladder training are more effective for urinary incontinence than estrogen therapy.

The evidence clearly demonstrates that systemic estrogen therapy increases the risk of developing urinary incontinence in postmenopausal women and should not be used as a treatment for this condition.