(a) IIEF-5 total score changes over time. Significant improvements with sildenafil and doxazosin GITS combined therapy (Group A) versus sildenafil monotherapy (Group B) were observed both at 3 and 6 months post-medication. (b) IIEF-5 mild score comparison between the two groups. In mild ED patients (IIEF-5: 17–21), no significant improvements with combined therapy versus monotherapy were observed both at 3 and 6 months post-medication (P>0.05). (c) IIEF-5 moderate score comparison between the two groups. In moderate ED patients (IIEF-5: 12–16), significant improvements with combined therapy versus monotherapy were observed at 6 months (P=0.000) post-medication but not at 3 months (P>0.05). (d) Severe ED patients IIEF-5 score comparison between the two groups. In severe ED patients (IIEF-5: 5–11), significant improvements with combined therapy versus monotherapy were observed both at 3 months (P=0.008) and 6 months (P=0.001) post-medication. *P<0.05, compared with Group B. Statistical difference analysis was carried out by analysis of variance of repeated data measured. ED, erectile dysfunction; IIEF-5, International Index of Erection Function-5; Pre Tx, pre-treatment.