Differences in PLNES in the treatment groups after 6 months and 12 months of intervention. The PLNES were reported as the mean ± s.d. (in cm). (a) After 6 months of treatment, the PLNES values were as follows: Group C, 6.42 ± 1.57; Group T, 7.04 ± 1.10; Group V, 7.72 ± 1.48; and Group T+V, 7.33 ± 1.78. (b) After 12 months of treatment, the PLNES values were as follows: Group C, 5.97 ± 1.40; Group T, 6.45 ± 1.12; Group V, 7.74 ± 1.49; and Group T+V, 7.40 ± 1.69. C: control group; T: tadalafil 5 mg oral OaD; V: vacuum erectile devices treatment for 15 min twice daily; T+V: tadalafil 5 mg oral OaD combined vacuum erectile devices treatment for 15 min twice daily. *P = 0.003 (Group T vs Group V); #P = 0.027 (Group T vs Group T+V), one-way ANOVA, P < 0.05 indicates statistical significant. ANOVA: analysis of variance; PLNES: penile length in the non-erectile state; s.d.: standard deviation; OaD: once a day.