Karimzadeh 2007.

Methods	RCT  Setting: Iran  Method of randomisation: computer‐generated sequences that was sealed in envelopes Blinding: double  Number randomised: 200
Participants	Summary: metformin vs placebo in non‐obese PCOS  Inclusion criteria: Rotterdam criteria 2003  Exclusion criteria: hyperprolactinaemia, CSH, thyroid disease, Cushings syndrome, androgen‐secreting tumour Baseline characteristics of each group: mean age (SD) 27.2 (6.8), 28.6 (7.4) mean BMI (SD) 28.3 (3.18), 29.5 (4.75) Dropouts: not mentioned
Interventions	Main intervention: metformin 500 mg 3/d, placebo  Duration: 3 months  Co‐interventions: nil
Outcomes	Primary: gastrointestinal side effects Secondary: clinical pregnancy rate, ovulation: progesterone > 10 ng/mL, BMI, fasting insulin, miscarriage
Notes	Women were recruited from a single centre. The primary objective of this study was to investigate the effect of metformin on lipid profile. The duration of the trial was relatively short. Therefore, it was difficult to ascertain the reliability on both of the ovulation rates and the improvement in menstrual patterns.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated sequences that were sealed in envelopes
Allocation concealment (selection bias)	Low risk	Sequences sealed in opaque envelopes and code kept in the pharmacy department
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding of participants and personnel
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding of investigators
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not stated
Selective reporting (reporting bias)	Unclear risk	Insufficient information in the study
Other bias	Low risk	No evidence of other bias