Morin‐Papunen 2003.

Study characteristics
Methods	Randomised controlled trial Location of the trial: quote: "Oulu, Finland" Method of randomisation: computer generated Method of allocation concealment: not stated Source of fundings: quote: "This research was supported by grants provided by the university of Oulu, the Finish Gynecological Association, the Sigrid Juselius Foundation and the Academy of Finland"
Participants	Inclusion criteria: non‐obese (BMI < 25 kg/m2) women. PCOS (Homburg 1996) i.e. PCO shown by vaginal ultrasonography (= 8 subcapsular follicles of 3 mm to 8 mm diameter in 1 plane in 1 ovary and increased stroma) and at least one of the following symptoms: (a) oligomenorrhoea or amenorrhoea; (b) clinical manifestations of hyperandrogenism, such as a F‐G hirsutism score of more than 7; acne; and/or (c) an elevated serum T level (> 2.7 n mol/L) Exclusion criteria: women with diabetes, smokers, alcohol users, and those taking sex hormones or drugs known to affect lipid metabolism during the two months preceding the study Number of women randomised: 20: MET arm: 10 OCP arm: 10 Number of women analysed: 17: MET arm: 8 OCP arm: 9 Number of withdrawal and reasons: 3 discontinued medication (2 in metformin arm, 1 in OCP arm). MET: 2: nausea and diarrhoea: 1/ 10% personal reasons 1/ 10% OCP: 1 headache and high blood pressure 1/ 10% Summary characteristics: PCOS, non‐obese women. Age (years): MET mean (± SE): 28.2(1.4) OCP mean (± SE): 28.5(1.7) BMI (kg/m2): MET mean (± SE): 22.5(0.8) OCP mean (± SE): 21.8(0.7)
Interventions	Treatment(s): MET 500 mg twice a day for 3 months, then 1000 mg twice a day for next 3 months Control: OCP (Ethinyl estradiol 35 mcg Cyproterone acetate 2 mg) once daily (21 days per month followed by 7 days pill‐free period) Duration: 6 months Co‐interventions: progestin to induce menses if necessary
Outcomes	Primary outcomes: Hirsutism score (F‐G) Adverse events: severe (requiring stopping of medication) and minor Secondary outcomes: Menstrual cyclicity, initiation of menses or significant shortening of cycles BMI (kg/m2) Serum total testosterone (nmol/L) Free androgen index (FAI) (%) Fasting insulin (pmol/L) Fasting glucose (mmol/L)
Subjective outcomes	(a) Clinical parameters 1. Hirsutism score (F‐G)
Objective outcomes	(a) Clinical parameters 1. Adverse events: severe (requiring stopping of medication) and minor 2.Menstrual cyclicity, initiation of menses or significant shortening of cycles 3. BMI (kg/m2) (b) Hormonal parameters 1. Serum total testosterone (n mol/L) 2. Free androgen index (FAI) (%) (c) Metabolic parameters 1.Fasting insulin (pmol/L) 2.Fasting glucose (mmol/L)
Notes	Authors contacted about: method of randomisation, reason for withdrawal and co‐intervention kindly provided by the authors that was not in the original paper Power calculation: NA
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The subjects were randomized to either the metformin group or to the EE=CA pill group". Insufficient information to permit judgement of ‘low risk’ or ‘high risk’.
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not stated. Insufficient information to permit judgement of ‘low risk’ or ‘high risk'.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Insufficient information available to permit a judgement of ‘low risk’ or ‘high risk’. Blinding not stated.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information available to permit a judgement of ‘low risk’ or ‘high risk’. Blinding not stated.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	"discontinue treatment, personal reason" unclear reason for withdrawal. Insufficient reporting of attrition/exclusions to permit a judgement of 'low risk' or 'high risk'.
Selective reporting (reporting bias)	Unclear risk	From results section of paper, all of the studies pre‐specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre‐specified way with the with the exception of weight which was only measured as BMI, BP and lipids. But not a primary or key outcomes. Insufficient information available to permit a judgment of 'low risk' or 'high risk'.
Other bias	Low risk	The study appears to be free of other sources of bias.