Kilic 2011.

Study characteristics
Methods	Randomised controlled trial Location of the trial: quote: Ankara, Turkey Method of randomisation: quote: "computer‐based randomized prospective analyses" Method of allocation concealment: not stated Source of funding: not stated
Participants	Inclusion criteria: PCOS according to the menstrual, laboratory, and ultrasonographic criteria of Rotterdam 2003. (Menstrual criteria included oligo‐ or amenorrhoea, irregular cycle length, > 45 days or less than six periods a year, ultrasound criteria used for diagnosis). Patients with normal androgen levels (the normal range values for serum‐free testosterone in our laboratory <3.17 ng/mL) with non obese and obese women with PCOS were selected. Exclusion criteria: for all participants included age less than 18 years or greater than 35 years, smoking, folic acid and vitamin B12 deficiency, pregnancy, hypothyroidism, hyperprolactinaemia, Cushing’s syndrome, nonclassical congenital adrenal hyperplasia (17 OHP <5 ng/dl) and current or previous (within the last 6 months) use of oral contraceptives, glucocorticoids, antiandrogens, ovulation induction agents, antidiabetic and anti‐obesity drugs, or other hormonal drugs. Women with clinical and/or biochemical hyperandrogenism alone were excluded from the study. Number of women randomised: 105 MET: 54: 28 BMI ≥ 25 / 26 BMI < 25 OCP: 51: 26 BMI ≥ 25 / 25 BMI < 25 Number of women analysed: 96 MET: 47 OCP: 49 Number of withdrawal and reasons: MET: Loss of F/U: 5 / 9.3% Discontinu: 2 / 3.7% OCP: Discontinu: 2 / 3.9% Summary characteristics: PCOS, normoandrogenaemic and oligoamenorrhoeic with impaired glucose tolerance Age (years): MET mean (+ SD): BMI ≥ 25: Age (years): 28.7 (3.7) BM I< 25: Age (years): 26.3 (3) OCP mean (+ SD): BMI ≥ 25: Age (years): 29 (3.5) BMI < 25: Age (years): 26.7 (3.8) BMI (kg/m2): MET mean (+ SD): BMI ≥ 25 BMI (kg/m2): 31.5 (2.1) BMI < 25 BMI (kg/m2): 23,37 (1.64) OCP mean (+ SD): BMI ≥ 25 BMI (kg/m2): 27.7 (0.9) BM I< 25 BMI (kg/m2): 21.63 (1.47)
Interventions	Treatment: MET 850 mg twice a day Control: OCP (Ethinyl estradiol 30 mcg desogestrel 0.15 mg) Duration: 6 months Co‐intervention(s): B‐groups vitamins vitamin B1.250 mg; vitamin B6.250 mg; vitamin B12.1000 mg, twice daily
Outcomes	Primary outcomes: Adverse events: severe (requiring stopping of medication) and minor Secondary outcomes: BMI (kg/m2)
Subjective outcomes	None
Objective outcomes	(a) Clinical parameters 1. Adverse events: severe (requiring stopping of medication) and minor 2. BMI (kg/m2)
Notes	Power calculation: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “computer‐based randomized prospective analyses”.
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not stated. Insufficient information available to permit a 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	"Loss of F/U" or "discontinue treatment" unclear reason of withdrawal and could be related to intervention. Insufficient report of attrition/ exclusions to permit a judgement of ‘low risk’ or ‘high risk’
Selective reporting (reporting bias)	Unclear risk	Testosterone is not reported in the results. But not a primary or key outcomes. Insufficient information available to permit a judgment of 'low risk' or 'high risk'.
Other bias	High risk	Baseline characteristic were not similar: BMI in metformin group higher than in OCP group in the subgroup BM I≥ 25kg/m2 MET mean (+ SD): 31.5 (2.1) / OCP mean (+SD): 27.7 (0.9)