However, all these studies were used just to compare the efficacy and safety of combination therapy (α1-blockers plus PDE5-Is) with monotherapy (α1-blockers or PDE5-Is alone); there was no study to compare the efficacy and safety of different combined arms (such as sildenafil plus tamsulosin versus vardenafil plus tamsulosin versus tadalafil plus tamsulosin) for treating BPH-LUTS with or without ED. This evidence concerns the gene PDE5A and benign prostatic hyperplasia.