Kim 2016.

Methods	Study design: randomised, double‐blind, placebo‐controlled trial Setting/country: USA Dates when study was conducted: 2006–2012
Participants	Inclusion criteria: IIEF ≥ 21, nsRP Exclusion criteria: known risk factors for ED, poor surgical candidates, health conditions that are potential contraindications for PDE5I therapy, prior treatment with PDE5I, and 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 Total number of participants randomly assigned: 97 Group A Number of participants randomly assigned: 49 Mean age (years): 54.3 (SD 7.1) Mean PSA (ng/mL): 5.1 (SD 2.9) Gleason score (pathological): 3 + 3: 35 (74.5%), 3 + 4: 6 (12.8%), 4 + 3: 3 (6.4%), 4 + 4: 3 (6.4%) Tumour stage (pathological): T1c: 34 (72.3%), T2a–T2c: 12 (25.5%), T3: 1 (2.1%) IIEF‐5: NR Mean IIEF‐EF: 28.0 (SD 4.6) Group B Number of participants randomly assigned: 48 Mean age (years): 54.3 (SD 7.1) Mean PSA (ng/mL): 4.2 (SD 2.8) Gleason score (pathological): 3 + 3: 39 (83.0%), 3 + 4: 5 (10.6%), 4 + 3: 0 (0.0%), 4 + 4: 3 (6.4%) Tumour stage (pathological): T1c: 30 (63.8%), T2a–T2c: 16 (34.0%), T3: 1 (2.1%) IIEF‐5: NR Mean IIEF‐EF: 28.3 (SD 5.5)
Interventions	Group A: nightly PDE5I (sildenafil 50 mg) Group B: placebo with 6 tablets of SC (100 mg) every 30 days for on‐demand use Surgery or cointervention: nsRP (RRP or RARP) Interval between surgery and intervention: 1 day Intervention duration: 12 months Washout period before outcome assessment: 1 month Total follow‐up period: 13 months
Outcomes	Primary outcomes Self‐reported potency; IIEF‐EF How measured: Rigiscan device; IIEF‐EF Questionnaire Time points measured: 2 weeks, and then at 3, 6, 9 and 12 months Time points reported: 2 weeks, and then at 3, 6, 9 and 12 months Secondary outcomes: NR Safety outcomes: NR Subgroup: none
Funding sources	Pfizer Inc.
Declarations of interest	None reported
Notes	Protocol: NA Language of publication: English
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Treatment arm was concealed from patients and clinical personnel until all interventions and assessments were complete."
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Quote: "Double‐blind" Judgement: not described who was blinded.
Blinding of outcome assessment (detection bias) Objective outcomes	Low risk	Objective outcomes were unlikely affected by lack of blinding.
Incomplete outcome data (attrition bias) Self‐reported potency	Low risk	2/49 (4.0%) participants in experimental group and 1/48 (2.0%) participant in control group were not included in analysis.
Incomplete outcome data (attrition bias) EF/IIEF	Low risk	2/49 (4.0%) participants in experimental group and 1/48 (2.0%) participant in control group were not included in analysis.
Incomplete outcome data (attrition bias) Serious adverse event	Unclear risk	No information given
Incomplete outcome data (attrition bias) Sexual quality of life	Unclear risk	No information given
Incomplete outcome data (attrition bias) Treatment discontinuation	Low risk	All participants included in analysis
Incomplete outcome data (attrition bias) Acceptability of the intervention	Unclear risk	No information given
Selective reporting (reporting bias)	Unclear risk	Predefined outcomes well described but protocol not available.
Other bias	Low risk	Not detected