Table 1. Randomised trials of oral phosphodiesterase type 5 inhibitors.

Authors	Year	Subjects	Treatment	Measure	Duration	Comment
Brock et al. 40	2003	440	Placebo versus vardenafil 10 mg, 20 mg	IIEF-EF Diary questions Global Assessment Question	3 months	Benefit in severe erectile dysfunction
Montorsi et al. 35	2008	628	Placebo versus vardenafil (5 mg to 20 mg); nightly versus on-demand	IIEF	9 months, 2-month washout	On-demand better than nightly, better than placebo
Padma-Nathan et al. 41	2008	76	Placebo versus nightly sildenafil 50 mg, 100 mg	IIEF	36 weeks, 8-week washout	Premature closing due to lack of treatment effect. Results after 12 months of follow-up; 4% of placebo patients regained spontaneous erection compared with 27% in treatment arm
Mulhall et al. 42	2013	298	Avanafil on-demand versus placebo	Sexual encounter profile (question 2) Sexual intercourse IIEF-EF	3 months
Pavlovich et al. 36	2013	100	Sildenafil; on-demand with nightly placebo versus nightly with on-demand placebo	Quality-of-life assessments	12 months, 1-month washout	No significant differences found. No sole placebo group
Montorsi et al. 37	2014	423	Placebo versus tadalafil; daily versus on-demand	IIEF-EF Sexual encounter profile Penile length	9 months, 6-week washout, 3-month open- label	Penile length loss reduced by 4.1 mm Unassisted erectile function not improved after treatment cessation. No benefit to tadalafil versus placebo
Moncada et al. 38	2015	423	Placebo versus tadalafil; daily versus on-demand	IIEF-EF	9 months, 6-week washout	IIEF-EF improved most with daily (29.5%, 23.9%,18.4% with IIEF ≥22)
Kim et al. 39	2016	74	On-demand sildenafil with addition of either nightly sildenafil or placebo	Rigiscan/IIEF	12 months, 1-month washout	No benefit of additional nightly dosing to on-demand. No pure placebo group

IIEF, International Index of Erectile Function; IIEF-EF, International Index of Erectile Function–erectile function domain.