Choi 1999.

Study characteristics
Methods	Study design: parallel randomized controlled clinical trial Randomization ratio: S. Korea (2:1); China (1:1); Singapore (1:1) (KRG: 40; placebo: 30) Dates when study was conducted: NR Setting/ countries: outpatient/ multi‐center (3)/ S. Korea, China, Singapore
Participants	Inclusion criteria: participants with penile rigidity under 70% on the audio visual sexual stimulation test under psychogenic ED, mild or moderate organic ED, ED from unknown cause Exclusion criteria: participants with definite organic ED and a need for surgical treatment Baseline characteristics of participants ‐ the number of participants randomized: 70 (Korea: 30; China: 20; Singapore: 20) (KRG: 40; Placebo: 30) ‐ the number of participants analyzed: 64 (KRG: 37; placebo: 27) ‐ age (mean): KRG: Korea ‐ 43.4, China ‐ 39.1, Singapore ‐ 50.2; placebo: Korea ‐ 45.2, China ‐ 42.9, Singapore ‐ 43.9 ‐ comorbidity: diabetes mellitus (KRG: Korea ‐ 4, China ‐ 0, Singapore ‐ 1; placebo: Korea ‐ 1, China ‐ 0, Singapore ‐ 2), hypertension (KRG: Korea ‐ 2, China ‐ 0, Singapore ‐ 3; placebo: Korea ‐ 1, China ‐ 0, Singapore ‐ 1), hypercholesterolemia (KRG: Korea ‐ 3, China ‐ 0, Singapore ‐ 2; placebo: Korea ‐ 0, China ‐ 1, Singapore ‐ 3) ‐ psychogenic ED (KRG: Korea ‐ 4, China ‐ 0, Singapore ‐ 1; placebo: Korea ‐ 2, China ‐ 0, Singapore ‐ 2), idiopathic (KRG: Korea ‐ 3, China ‐ 8, Singapore ‐ 0; placebo: Korea ‐ 3, China ‐ 7, Singapore ‐ 0) ‐ ED severity (mean): libido: 4.4 (KRG: 5.8; placebo: 4.7) erection: 14.0 (KRG: 19.0; placebo: 16.0) ejaculation: 5.8 (KRG: 8.4; placebo: 6.1) sexual activity: 9.8 (KRG: 13.0; placebo: 11.0) satisfaction: 7.2 (KRG: 10.0; placebo: 7.8)
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 (same shape and appearance as KRG) Run‐in period: no Follow‐up period: 12 weeks
Outcomes	1) Erectile function: How measured: questionnaire (not validated, items [libido, erection, ejaculation, sexual activity, satisfaction]) Time points measured: at baseline and 12 weeks Time points reported: at baseline and 12 week 2) AEs: How measured: NR Time points measured: NR Time points reported: likely cumulative
Funding sources	KT&G Corp.
Declarations of interest	NR
Notes	Publication language: Korean
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomly divided to KRG and placebo" 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)	High risk	Quote: "... single blinded... The placebo group received the same shape and appearance with KRG group." Comment: the appearances of the treatments were the same in both groups but noted as single blind.
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Quote: "... single blinded...", " The placebo group received the same shape and appearance with KRG group." Comment: the appearances of the treatments were the same in both groups but noted as single blind.
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: "6 patients were not assessed in the follow‐up assessment" Comment: 37/40 and 27/30 randomized participants in the KRG and placebo groups, respectively, were included in the analysis.
Incomplete outcome data (attrition bias) Adverse events	Low risk	Quote: "6 patients were not assessed in the follow‐up assessment" Comment: 37/40 and 27/30 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: "6 patients were not assessed in the follow‐up assessment" Comment: 37/40 and 27/30 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: insufficient information available to permit a judgement and there was no published protocol.
Other bias	Unclear risk	Comment: likely baseline imbalance in severity of sexual functions between the groups.