Dardzinska 2014.

Study characteristics
Methods	Randomised controlled trial, cross‐over study Location of the trial: quote: Gdynia, Poland Method of randomisation: quote: "Women were treated in a computer‐randomized order" Method of allocation concealment: not stated Sources of fundings: Quote: "This study has been founded by the Polish National Centre of Science (grant number 2 P05E 077 30) and the Medical University of Gdańsk Grant (ST‐101)"
Participants	Inclusion criteria: the diagnosis of PCOS was made according to the Rotterdam criteria where the study participants had to present at least 2 of the 3 following features: oligo‐/amenorrhoea, clinical/biochemical indices of hyperandrogenism or polycystic ovaries on transvaginal ultrasonography. Exclusion criteria: hyperprolactinaemia, non‐classical congenital adrenal hyperplasia and androgen producing neoplasms. Participants who had received any medication such as oral contraceptives, antiandrogens, neuroleptics, antidepressants or corticosteroids in the preceding 3 months were not included into the study. Furthermore, women with diagnosed diabetes, overt thyroid disease, chronic inflammatory disorders or a history of infection preceding 1 month before the study were also excluded. Pregnancy, age more than 40 years and contraindications to oral contraception or metformin were additional exclusion criteria. Number of women randomised: 42 OCP arm: 24 MET arm: 18 Number of women analysed: 34 OCP: 21 MET: 13 Number of withdrawal and reasons: OCP: 3: Loss to F/U: 1/ 4.2% Intolerance: 2/ 8.3% MET: 5 Loss to F/U: 4/ 22% Depression: 1/ 5.5% Summary characteristics: PCOS, age range 18 to 36, 20% smokers Age (years): OCP mean (95%CI): 24.9 (23.5; 26.4) MET mean (95%CI): 24.6 (23.0; 26.3) BMI (kg/m2): OCP: mean (+SD): 24.9 (4.4) MET: mean (+SD): 25.1 (9.8)
Interventions	Treatment: MET 850 mg twice a day Control: OCP (Ethinyl Estradiol 35 mcg Cyproterone acetate 2mg) Duration: 4 months Co‐intervention(s): none
Outcomes	Primary outcomes: Hirsutism score Adverse events: severe (requiring stopping of medication) and minor Secondary outcomes: Body weight (kg) BMI (kg/m2) Blood pressure (systolic) (mm Hg) Blood pressure (diastolic) (mm Hg) Serum total testosterone (nmol/L) Free androgen index (FAI) (%) Fasting glucose (mmol/L) Fasting total cholesterol (mmol/L) Fasting HDL cholesterol (mmol/L) Fasting LDL cholesterol (mmol/L) Fasting triglycerides (mmol/L)
Subjective outcomes	(a) Clinical parameters 1. Hirsutism score
Objective outcomes	(a) Clinical parameters 1. Adverse events: severe (requiring stopping of medication) and minor 2. Body weight (kg) 3. BMI (kg/m2) 4. Blood pressure (systolic) (mm Hg) 5. Blood pressure (diastolic) (mm Hg) (b) Hormonal parameters 1. Serum total testosterone (nmol/L) 2. Free androgen index (FAI) (%) (c) Metabolic parameters 1. Fasting glucose (mmol/L) 2. Fasting total cholesterol (mmol/L) 3. Fasting HDL cholesterol (mmol/L) 4. Fasting LDL cholesterol (mmol/L) 5. Fasting triglycerides (mmol/L)
Notes	Authors contacted about the results, they send us the results before cross‐over Power calculation: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Women were treated in a computer‐randomized order”.
Allocation concealment (selection bias)	Unclear risk	Method of 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” unclear reason for withdrawal could be related to intervention. 2 “intolerance” in OCP group so related to the intervention, 1 “depression” in MET group unlikely related to the intervention. Insufficient reporting of attrition/ exclusions to permit a judgement of 'low risk' or 'high risk'.
Selective reporting (reporting bias)	Unclear risk	Fasting glucose pre‐specified in the methods not stated 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	Number of patients randomised in each group is different 24 versus 18 and more withdrawal in the smallest group. Baseline imbalance.