Kar 2015.

Methods	RCT Setting: India (private hospital) Method of randomisation: envelopes prepared by a nurse "naive to this study" Blinding: double‐blind Number randomised: 105
Participants	Summary: metformin and CC vs CC vs metformin in Asian Indian women with "treatment naive" PCOS Inclusion criteria: history of infertility and oligomenorrhoea, meeting the Rotterdam criteria for PCOS Normal male factor, at least 1 patent tube by hysterosalpingography, treatment naive Exclusion criteria: any major systemic illness Baseline characteristics of each group: metformin and CC (n = 24) vs metformin (n = 24) vs CC (n = 32) Mean age (SD) 26.62 (3.54) vs 25.2 (3.47) vs 25.8 (2.46) MEan BMI (SD) 27.2 (3.7) vs 24.5 (5) vs 26.5 (3.7) Mean fasting insulin (SD) 12.85 (14.05) vs 10.32 (7.48) vs 14.14 (9.88) Mean fasting glucose (SD) 94.55 (15.8) vs 90.18 (8.39) vs 95.25 (12.54) Dropouts: 25 (3 in the CC group, 11 in metformin group, 11 in combined group)
Interventions	Main intervention: 3 equal groups. Group 1: CC 50‐150 mg/d. Group 2: metformin 1700 mg/d. Group 3: CC plus metformin, doses as above) Duration: 6 months, or until pregnant, or until resistant to CC Co‐interventions: not applicable
Outcomes	Primary: live birth rate Secondary: ovulation: follicle tracking on US, clinical pregnancy rate, miscarriage
Notes	We have contacted the study authors for further information regarding methodology No units provided for fasting insulin and fasting glucose levels
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of generating random sequence for distribution in envelopes not stated
Allocation concealment (selection bias)	Unclear risk	Allocation revealed in envelopes but not clear if opaque or sealed
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants and personnel were blinded
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of investigators unclear
Incomplete outcome data (attrition bias) All outcomes	High risk	22.9% dropout rate, without reasons given Data analysis not performed as ITT
Selective reporting (reporting bias)	Unclear risk	Insufficient information in the study. 3‐arm study however data presented for all 3 arms clearly
Other bias	Low risk	No evidence of other bias