1. Baseline characteristics.

Study	Trial period	Setting/country	Description of participants	Intervention(s) and comparator(s)	Duration of intervention, washout and total follow‐upa	Mean age (SD)	Mean PSA (SD)	Pathological Gleason score n (%)	Pathological tumour stage n (%)
Aydogdu 2011	2006–2008	Single institution/Turkey	Men aged < 65 years, preoperative full potency (IIEF‐EF scores > 25 and answered SEP questions 2–3 'yes'), no history of penile plaques or previous penile surgery, clinical stage T1c or lower, PSA < 10 ng/mL and a biopsy Gleason score < 8. No exclusion criteria reported	Tadalafil 20 mg/day, 3 days/week	Intervention: 6 months Washout: 5 months and 10–14 days Follow‐up: 12 months	56.2	6.3	NR	NR
				No treatment		58.1	5.8	NR	NR
Kim 2016	2006–2012	Single institution/USA	Men with localised prostate cancer who elected to go surgical treatment. These men had normal preoperative EF, defined as Sexual Health Index for Men score ≥ 21 and at > 1 erectile event with tip penile rigidity > 60% and lasting > 10 minutes in duration documented by Rigiscan. Men with known risk factors for ED and men with health conditions which are potential contraindications for PDE5I therapy were excluded from study. Men taking potent cytochrome P450 inhibitors or alpha‐adrenergic blocking agents (which could interact with sildenafil), or with known hypersensitivity to sildenafil or other ingredients of Viagra were also excluded.	Nightly sildenafil 50 mg + 6 tablets of sildenafil 100 mg per month for on‐demand use	Intervention: 12 months Washout: 1 month Follow‐up: 13 months	54.3 (7.1)	5.1 (2.9)	3+3: 35 (74.5) 3+4: 6 (12.8) 4+3: 3 (6.4) 4+4: 3 (6.4)	T1c: 34 (72.3) T2a‐T2c: 12 (25.5) T3:1 (2.1)
				Matched placebo + 6 tablets of sildenafil 100 mg per month for on‐demand use		53.7 (7.1)	4.2 (2.8)	3+3: 39 (83.0) 3+4: 5 (10.6) 4+3: 0 (0.0) 4+4: 3 (6.4)	T1c: 30 (63.8) T2a‐T2c: 16 (34.0) T3: 1 (2.1)
McCullough 2010	NA	Multicentre/USA	Men aged < 70 years, sexually active in a stable relationship, with normal EF as determined by IIEF‐EF questionnaire (IIEF‐EF score ≥ 26) and scheduled to undergo bilateral nsRP were included. Those men with Gleason Score > 7, PSA > 20 ng/mL and postoperative RT or ADT were excluded.	Nightly sildenafil 50 mg	Intervention: 9 months Washout: 1 month Follow‐up: 11 months	55.6 (5.9)	NR	NR	NR
				Nightly intraurethral alprostadil		56.8 (6.4)	NR	NR	NR
Montorsi 2008	2004–2007	87 centres across Europe, the US, Canada, and South Africa	Men, aged 18–64 years, in a heterosexual relationship, and scheduled to undergo bilateral NSRP within approximately 1mo of screening; an interest in resuming sexual activity as soon as possible after surgery; normal preoperative EF (IIIEF ≥ 26 at screening without the use of therapy or devices for the improvement of erections and no previous use of therapy or devices for ED; historical total PSA <10 ng/ml; Gleason tumour score ≤ 7 on biopsy; no tumour perforation of the prostate capsule were included. Men who had residual prostate cancer or requirement for RT or adjuvant therapy; need for further surgery due to haemorrhage; and urethral catheter expected to be in place for ≥ 3 weeks due to anastomotic fistula; had contraindication of PDE5I were excluded.	Nightly vardenafil 10 mg (which could be decreased to 5 mg if required) plus on‐demand placebo	Intervention: 9 months Washout: 2 months Follow‐up: 13.5 months	57.4	NR	NR	NR
				Flexible‐dose (starting at 10 mg with the option to titrate to 5 mg or 20 mg), on‐demand vardenafil plus nightly placebo		56.8	NR	NR	NR
				Nightly placebo, on‐demand placebo		57.1	NR	NR	NR
Montorsi 2014	2009–2011	Multicentre/Europe & Canada	Men aged < 68 years with normal EF who underwent nsRP for organ‐confined, non‐metastatic prostate cancer (Gleason Score ≤ 7, PSA ≤ 10 ng/mL). Postsurgical inclusion criteria included the development of ED as measured by a participant‐reported Residual Erection Function Score of ≤ 3 (= "penis is hard enough for penetration but not completely hard") were included. Men 1) with history of ED 2) who received prior PDE5I treatments 3) who received neoadjuvant RT or a ADT or were due to receive adjuvant RT or ADT, 4) with history of prostatic surgery or prostatic physical treatments, 5) with history of diabetes mellitus, 6) with history of galactose intolerance, lapp lactase deficiency, or glucose‐galactose malabsorption 7) who have clinically significant renal insufficiency were excluded.	Tadalafil 5 mg once daily	Intervention: 9 months Washout: 6 weeks Follow‐up: 13.5 months	58.6 (5.07)	NR	NR	NR
				Tadalafil 20 mg on‐demand		57.5 (5.91)	NR	NR	NR
				Placebo		57.6 (5.69)	NR	NR	NR
Pace 2010	2005–2009	Single centre/Italy	Men with total PSA level < 10 ng/mL, Gleason score ≤ 7 on biopsy, no capsular involvement, a normal preoperative EF assessed by an IIEF score ≥ 26, without the use of any therapy for improving erection	Sildenafil 50 mg or 100 mg at night for 8 weeks	Intervention: 8 weeks Washout: 14 weeks Follow‐up: 24 months	NR	5.5 (range 1.2–9.9)	6: 18 (90.0%) 7: 2 (10.0%)	T1b and T1c: 10 (50.0%), T2a: 9 (45.0%), T2b: 1 (5.0%)
				No treatment		NR	6 (range 1.8–8.9)	6: 18 (90.0%) 7: 2 (10.0%)	T1b and T1c: 9 (45.0%); T2a: 9 (45.0%); T2b: 2 (10.0%)
Padma‐Nathan 2008	1999–2001	16 sites in North America, France, Belgium and Australia screened participants, and 11 sites in North America and France	Men aged 18–70 years, weighing 50–125 kg who had to had normal preoperative EF (combined score ≥ 8 on questions 3 and 4 of the IIEF questionnaire) and wish to return to sexual activity after surgery and be in a stable, heterosexual relationship for the past 6 months	Sildenafil 100 mg once nightly	Intervention: 36 weeks Washout: 8 weeks Follow‐up: 48 weeks	55 ± 6/	NR	NR	NR
				Sildenafil 50 mg once nightly		55 ± 6	NR	NR	NR
				Placebo once nightly		57 ± 7	NR	NR	NR
Pavlovich 2013	2006– 2007	Single institution/USA	Men who chose to undergo nsRP who satisfied the following criteria: aged < 65 years, untreated prostate cancer < cT2b, biopsy Gleason score < 8, baseline IIEF‐EF score ≥ 25/30, no PDE5I use, and presence of a steady sexual partner	Nightly sildenafil 50 mg with on‐demand placebo	Intervention: 12 months Washout: 4 weeks Follow‐up: 13 months	54.3 (range 2–63)	4.7 (range 0.6–14)	6: 41 (82.0%) 7: 9 (18.0%)	T1c: 37 (74.0%), T2a: 13 (26.0%)
				On‐demand sildenafil 50 mg (maximum 6 tablets/month) with nightly placebo		53.6 (range 40–64)	5.1 (range 0.8–9.0)	6: 42 (84.0%)/7: 8 (16.0%)	T1c: 40 (80.0%); T2a: 10 (20.0%)

ADT: androgen deprivation therapy; ED: erectile dysfunction; EF: erectile function; IIEF‐EF: International Index of Erectile Function – Erectile Function domain; n: number of participants; NA: not applicable; NR: not reported; nsRP: nerve‐sparing radical prostatectomy; PDE5I: phosphodiesterase Inhibitor 5 inhibitor; PSA: prostate‐specific antigen; RT: radiotherapy; SD: standard deviation; SEP: Sexual Encounter Profile.

^aIntervention started within 1 month after surgery in all included studies except Montorsi 2008 (14 days after surgery) and Montorsi 2014 (starting date of intervention: not defined).