Feng 2016.

Study characteristics
Methods	Randomised controlled trial Location of the trial: quote: Zhengzhou, China Method of randomisation: quote: "The study participators were randomly divided into two groups using a table of random numbers." Method of allocation concealment: quote: "Preparation of the medication was performed in a centralized manner, and labeling, with the exception of the relevant randomization code, was identical in all presentations." Source of fundings: not stated
Participants	Inclusion criteria: PCOS: Rotterdam criteria: (1) oligo/anovulation, (2) signs of hyperandrogenism (i.e. hirsutism and acne) or (3) enhanced ovaries (at least 12 discrete follicles of 2 mm to 9 mm in diameter in one ovary or the ovarian volume > 10 cm3 observed by transvaginal ultrasonography)Exclusion criteria: women with androgen‐excess disorders or patients with specific aetiologies such as congenital adrenal hyperplasia, Cushing’s syndrome, thyroid hormone abnormalities, hyperprolactinaemia, or ovarian/adrenal tumours. Furthermore, all patients had no history of previous first‐trimester miscarriage or pregnancy. The patients with more than one outlier baseline parameter data using the Grubbs test were also excluded in the following clinical trial study.Number of women randomised: 82: OCP + MET arm: 41 OCP arm: 41Number of women analysed: not statedNumber of withdrawal and reasons: not statedSummary characteristics: PCOS, mean age for the whole cohort: 29.0 yearsAge (years): OCP + MET mean (+ SD): 27.86 (3.79) OCP mean(+ SD): 28.57 (3.04)BMI (kg/m2): OCP + MET mean (+ SD) 29.46 (4.43) OCP mean(+ SD) 27.77 (4.23)
Interventions	Treatment: OCP (Ethinyl Estradiol 35 mcg Cyproterone acetate 2 mg) cyclically 21 days stop 7 days + MET 425 mg twice a day then 850 mg twice a day Control: OCP (Ethinyl Estradiol 35 mcg Cyproterone acetate 2 mg) cyclically 21 days stop 7 days Duration: 3 months Co‐intervention(s): none
Outcomes	Primary outcomes: Hirsutism score Secondary outcomes: Acne score BMI (kg/m2) Blood pressure (systolic) (mm Hg) Blood pressure (diastolic) (mm Hg) Serum total testosterone (nmol/L) Fasting insulin (mIU/L) 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 2.Acne score
Objective outcomes	(a) Clinical parameters 1. BMI (kg/m2) 2. Blood pressure (systolic) (mm Hg) 3. Blood pressure (diastolic) (mm Hg) (b) Hormonal parameters 1.Serum total testosterone (nmol/L) (c) Metabolic parameters 1. Fasting insulin (mIU/L) 2. Fasting glucose (mmol/L) 3. Fasting total cholesterol (mmol/L) 4. Fasting HDL cholesterol (mmol/L) 5. Fasting LDL cholesterol (mmol/L) 6. Fasting triglycerides (mmol/L)
Notes	Authors contacted about the number of patient randomised in each group and number of withdrawal Power calculation: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “The study participators were randomly divided into two groups using a table of random numbers”
Allocation concealment (selection bias)	Low risk	Quote: “Preparation of the medication was performed in a centralized manner, and labelling, with the exception of the relevant randomization code, was identical in all presentations”
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "This study was carried out in double‐blind conditions, so neither the patient nor the doctor was aware of the composition of the treatment administered.” The “doctor” could be the clinician or outcome assessor. Insufficient information available to permit a judgement of “low risk” or “high risk”.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: “This study was carried out in double‐blind conditions, so neither the patient nor the doctor was aware of the composition of the treatment administered.” The “doctor” could be the clinician or outcome assessor. Insufficient information available to permit a judgement of “low risk” or “high risk”.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Paper does not provide any information on participant after randomisation.
Selective reporting (reporting bias)	Unclear risk	Body weight prespecified in the methods 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	Low risk	The study appears to be free of other sources of bias.