Finasteride for Benign Prostatic Hyperplasia
For benign prostatic hyperplasia, finasteride (5 mg/day) is an effective, guideline-recommended treatment that shrinks the prostate and eases urinary symptoms, but the benefit is meaningful mainly in men with an enlarged prostate (roughly >=30 mL), works slowly, and carries a real risk of sexual side effects.
Why this grade7-layer evidence engine
This earns a Moderate (A) grade because the efficacy evidence is consistent and high-quality, yet bounded by who actually benefits and offset by safety caveats. A systematic review of 22 randomized trials (PMID 12477383; n=14,729) found finasteride cut symptom scores more than placebo (3.7 vs 2.3 points), improved peak urine flow by about 1.3 mL/s, shrank the prostate ~25%, and lowered the long-term need for surgery (NNT 18) and acute urinary retention (NNT 26). A 2022 meta-analysis (PMID 35402192; n=2,116) showed it performs about as well as dutasteride, supporting class-level efficacy.
The key limitation is scope: a long-term MTOPS analysis (PMID 21334655) found the progression benefit was real only in prostates >=30 mL (88.1% vs 77.8% progression-free, p<0.001) and absent in smaller prostates. This is why the American Urological Association (L5e) recommends 5-alpha-reductase inhibitors specifically for men with prostate enlargement, and why Cleveland Clinic and Harvard Health describe the drug as shrinking the prostate to relieve symptoms.
Safety tempers the verdict. The 22-trial review reported sexual adverse events (NNH 14, e.g. impotence 8% vs 3%), and the FDA, UK NHS, and WHO all flag sexual dysfunction, including symptoms that can persist after stopping. A large PCPT trial (PMID 23944298; n=18,880) found no survival difference and a borderline high-grade prostate-cancer signal (RR 1.17, p=0.05) now widely attributed to detection bias, not true added risk. Effects take 3-6 months and reverse if the drug is stopped.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.73
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status