Ashrafinia 2009.

Methods	A randomised controlled trial
Participants	126 women with PCOS were randomised from March 2006 until February 2008, between the ages of 15 and 45 years, with a history of infertility for at least 1 year and 3 treatment cycles with no response to CC (CC‐resistant), conducted in Tehran, Iran
Interventions	Participants received metformin treatment (n = 63) or underwent LOD (n = 63)
Outcomes	The primary outcome measure was menstrual regularity. The levels of FSH, LH, free testosterone and the level of hirsutism assessed using the Ferriman Gallwey score were included. No harms reported.
Notes	Funding source: Not stated Declarations of interest: 'None'. Authors contacted requesting further information.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Low risk	The groups were allocated using serially‐numbered opaque envelopes
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not stated but not possible with study design
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	All randomised women were analyzed
Selective reporting (reporting bias)	Low risk	None detected
Other bias	Low risk	None detected