Raja 2005.

Methods	RCT Setting: Pakistan Method of randomisation: unclear Blinding: single‐blinded (ultrasonographers were blinded) Number randomised: 100
Participants	Summary: metformin and CC vs CC alone Inclusion criteria: PCOS (diagnosed by presence of PCO on ultrasound and ≥ 2 of oligomenorrhoea, hirsutism, hyperandrogenism, elevated LH or LH:FSH ratio). Tubal patency and normal semen analysis Exclusion criteria: other endocrine disorders including congenital adrenal hyperplasia, Cushing's syndrome, hyperprolactinaemia and thyroid disease Baseline characteristics of each group: metformin and CC vs CC alone Mean age (SD) 26.52 (2.3) vs 26.88 (2.4) Normal menstrual cycle (number) 32 (64%) vs 28 (56%) Mean testosterone levels Dropouts: none
Interventions	Main intervention: metformin 500 mg 3/d Duration: 6 cycles Co‐interventions: CC 50 mg from day 2 until day 6 of cycle
Outcomes	Primary: gastrointestinal side effects Secondary: clinical pregnancy rate, ovulation: follicle tracking on transvaginal US and day 21 progesterone > 8 mg/mL, adverse effects: teratogenic effects
Notes	Old paper ‐ unable to read baseline testosterone levels No information on method of randomisation
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No method of randomisation
Allocation concealment (selection bias)	Unclear risk	No information available
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information available
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information available
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts
Selective reporting (reporting bias)	Unclear risk	Insufficient information in the study
Other bias	Low risk	No evidence of other bias, however, reporting of methodology limited