#316 To Pee or Not to Pee: Combination agents for benign prostatic hypertrophy
CLINICAL QUESTION
For patients with benign prostatic hypertrophy (BPH) is combination therapy with alpha-blockers and 5-alpha reductase inhibitors (5ARI) more efficacious than alpha-blockers alone?
BOTTOM LINE
At best, adding 5ARIs to alpha-blockers reduces the number of men with clinical progression (5% compared to 10% on alpha-blocker alone), and the number needing BPH surgery (2% compared to 8% on alpha-blocker alone). Drug related adverse effects are increased from 19% on alpha-blockers alone to 28% on combination.
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EVIDENCE
- Systematic review1 identified 6 RCTs, 2 with >1 year follow-up.2,3 Enrolled patients were symptomatic white males receiving additional testing (example transrectal ultrasound) and specialist care.2,3 Four-year outcomes reported below.
- Doxazosin (1mg titrated up to 8mg), doxazosin plus finasteride (5mg), or placebo (n=3,047):2
- Clinical progression: Composite of worsening symptoms [>4 point change on 35-point American Urological Association Score], acute retention, incontinence, or recurrent urinary tract infection (UTI). Symptom progression contributed ~80% of the composite.
- Doxazosin 10%, combination 5%: Number needed to treat (NNT)=20 (placebo 17%).
- BPH surgery:
- Doxazosin 3%, combination 1%: NNT=50 (placebo 5%).
- Adverse effects, statistics not reported:4
- Decreased erectile function: Doxazosin 13%, combination 17% (placebo 13%).
- Tamsulosin (0.4mg) or tamsulosin plus dutasteride (0.5mg) (n=4,844):3
- Clinical progression: Composite of worsening symptoms [≥ 4-point change on 35-point International Prostate Symptom Score], acute retention, incontinence, recurrent UTI, urosepsis or renal insufficiency. Symptom progression contributed ~65% of the composite.
- Tamsulosin 22%, combination: 13%: NNT=12.
- BPH surgery:
- Tamsulosin 8%, combination 2%: NNT=23.
- Adverse effects:
- Any drug related adverse effect: Tamsulosin 19%, combination 28%; number needed to harm=12.
- Erectile dysfunction: Tamsulosin 5%, combination 9%, not statistically different.
- Dizziness: No difference.
- Clinical progression: Composite of worsening symptoms [≥ 4-point change on 35-point International Prostate Symptom Score], acute retention, incontinence, recurrent UTI, urosepsis or renal insufficiency. Symptom progression contributed ~65% of the composite.
- Clinical progression: Composite of worsening symptoms [>4 point change on 35-point American Urological Association Score], acute retention, incontinence, or recurrent urinary tract infection (UTI). Symptom progression contributed ~80% of the composite.
- 5ARI may decrease prostate cancer incidence, but cancers found may be higher grade.5,6
- 17-year follow-up: No difference in prostate cancer mortality.7
- 5ARI decreases prostate serum antigen (PSA) levels by ~50%,8 which might delay prostate cancer diagnosis.9
- If following, PSA should be multiplied by 2-2.3 for patients on 5ARI.5,6
- Canadian guidelines recommend:10
- Alpha-blockers: First line.
- Combination: If prostate enlargement.
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