Yarali 2002.

Methods	RCT Setting: Turkey Method of randomisation: computer‐generated numbers. Centralised randomisation process* Blinding: double‐blind Number randomised: 32
Participants	Summary: metformin vs placebo in non‐obese PCOS, CC resistance Inclusion criteria: PCOS (oligomenorrhoea < 6 cycles/year, anovulation confirmed with progesterone < 5 ng/mL, testosterone > 2.4 nmol/L, exclusion of other endocrinopathy, US findings of PCO, CC resistance to 250 mg for 5 d for up to 6 months, normal semen analysis, normal HSG or laparoscopy within 6 months Exclusion criteria: diabetes mellitus, adrenal hyperplasia, Cushing’s syndrome, thyroid dysfunction, hyperprolactinaemia, medication known to alter insulin action, previous gonadotrophin treatment, infertility other than that caused by PCOS, previous pelvic surgery Baseline characteristics of each group: metformin (n = 16) vs placebo (n = 16) mean age (± SD) 29.7 (5.6), 28.4 (5.1) mean BMI (± SD) 28.6 (4.0), 29.6 (4.8) mean fasting insulin mIU/L (± SD) 15.5 (21.4), 11 (5.5) mean total testosterone mmol/L (± SD) 6.19 (3.57), 6.01 (2.93) Dropouts: 2 (6%) from the metformin/placebo part of the study owing to pregnancy. They were excluded from analysis
Interventions	Main intervention: 1 of metformin 850 mg 2/d, placebo Duration: 6 weeks initially, then those who did not ovulate continued for 1 cycle Co‐interventions: those that did not ovulate after 6 weeks had recombinant FSH in a low‐dose, step‐up protocol No change in usual eating habits
Outcomes	Primary: none Secondary: live birth rate, gastrointestinal side effects, pregnancy rate, ovulation: serum progesterone > 15.9 nmol/L weekly, BMI, fasting glucose, fasting insulin, total and free testosterone
Notes	Free testosterone was significantly higher in the metformin group. Fasting insulin was non‐significantly higher with a wide SD compared with placebo *Information not in the original paper kindly provided by the study author
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated numbers. Centralised randomisation process*
Allocation concealment (selection bias)	Unclear risk	Inadequate information
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Inadequate information
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Inadequate information
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropouts: 2 (6%) from the metformin/placebo part of the study owing to pregnancy. They were excluded from analysis
Selective reporting (reporting bias)	Unclear risk	Inadequate information
Other bias	Low risk	No evidence of other bias