Choi 2003.

Study characteristics
Methods	Study design: parallel randomized controlled clinical trial Randomization ratio: 2:1 (KRG: 20, placebo: 10) Dates when study was conducted: NR Setting/country: outpatient/ single center/ S. Korea
Participants	Inclusion criteria: participants with clinical ED, without definite organic cause Exclusion criteria: 1) anatomic penile disorder 2) decreased libido without ED 3) elevated prolactin (over three times the upper limit) or decreased free testosterone (less than 80% of the lower limit) 4) psychologic disorder (major depression or schizophrenia) 5) ED from spinal cord injury 6) history of alcohol abuse or drug abuse 7) history of hematologic disease, renal disease, hepatic disease 8) refractory diabetes mellitus Baseline characteristics of participants ‐ the number of participants randomized: 30 (KRG: 20, placebo: 10) ‐ the number of participants analyzed: 28 (KRG: 19, placebo: 9) ‐ age (mean): KRG: 45.1; placebo: 44.4 ‐ comorbidity: unclear ‐ ED severity: NR
Interventions	Details of intervention and control ‐ Experiment: KRG (1800 mg; 2 tablets of 300 mg 3 times daily) (commercial product from KT&G) ‐ Control: placebo (NR in detail) Run‐in period: no Follow‐up period: 4 weeks
Outcomes	1) AEs: How measured: NR TIme points measured: NR Time points reported: likely cumulative 2) Participant's ability to have intercourse reported by participant (or partner): How measured: number of participants with improvement in the total score of IIEF‐15 compared with baseline TIme points measured: at 4 weeks Time points reported: at 4 weeks
Funding sources	KT&G
Declarations of interest	NR
Notes	Publication language: Korean The authors did not reported the score for each domain of the IIEF
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "... randomly assigned..." Comment: no explicit explanation of the sequence generation.
Allocation concealment (selection bias)	Unclear risk	Comment: no detailed information about allocation concealment.
Blinding of participants and personnel (performance bias)	Low risk	Comment: the appearance of each treatment was the same and adequately used.
Blinding of outcome assessment (detection bias) Subjective outcomes	Low risk	Comment: placebo controlled trial.
Blinding of outcome assessment (detection bias) Objective outcome: adverse events	Low risk	Comment: objective outcome was not likely affected by lack of blinding.
Incomplete outcome data (attrition bias) Erectile function and sexual satisfaction	Low risk	Quote: "2 patients were not assessed in the follow‐up assessment" Comment: 19/20 and 9/10 randomized participants in the KRG and placebo groups, respectively, were included in the analysis.
Incomplete outcome data (attrition bias) Adverse events	Low risk	Quote: "2 patients were not assessed in the follow‐up assessment" Comment: 19/20 and 9/10 randomized participants in the KRG and placebo groups, respectively, were included in the analysis.
Incomplete outcome data (attrition bias) Ability to have intercourse reported by participants (or partner)	Low risk	Quote: "2 patients were not assessed in the follow‐up assessment" Comment: 19/20 and 9/10 randomized participants in the KRG and placebo groups, respectively, were included in the analysis.
Incomplete outcome data (attrition bias) QoL	Unclear risk	Comment: not measured.
Selective reporting (reporting bias)	Unclear risk	Comment: the outcomes were described well but the protocol was not published.
Other bias	Unclear risk	Comment: the severity of erectile dysfunction at baseline was not reported for the study groups.