Risk factors for failure of long-term dutasteride add-on treatment to alpha-adrenergic antagonist for patients with lower urinary tract symptoms and benign prostatic enlargement.

Purpose: To identify the clinical factors resulting in the failure of dutasteride add-on treatment to alpha-adrenergic antagonist for patients with lower urinary tract symptoms and benign prostatic enlargement (BPE).

Methods: We retrospectively surveyed the patient cohort who had been enrolled in the study of dutasteride add-on treatment to alpha-adrenergic antagonist from December 2009 to November 2011. Treatment failure was defined as receiving surgery for BPE or requiring intermittent catheterization or permanent bladder catheter for urinary retention or huge postvoid residual urine. Clinical parameters before dutasteride treatment were compared between the successful and failed group.

Results: Of 92 patients, 23 (25%) were defined as treatment failure at 7-109 months (mean: 38 months) after dutasteride add-on treatment. In the failed group, the patient' age was younger (71.6  ±  6.8 vs 75.4  ±  8.4, p = 0.033), prostatic volume (PV) was larger (76  ±  41 vs 49  ±  26 ml, p = 0.005), voiding efficiency was lower (54  ±  27 vs 68  ±  24%, p = 0.045) and bladder outlet obstruction index was higher (73  ±  30 vs 48  ±  30, p = 0.015). The cox proportional-hazards model indicated that only intravesical prostatic protrusion (IPP) was associated with treatment failure. Non-failure rate at 3 years after dutasteride add-on treatment was 89% with patients of IPP < 13 mm versus 51% with those of IPP ≥ 13 mm (p < 0.001).

Conclusion: IPP ≥ 13 mm is the risk factor resulting in the failure of dutasteride add-on treatment to alpha-adrenergic antagonist. This kind of information should be provided to the patients early in the clinical practice so that they could consider the necessity of BPE surgery in the long run.