Razavi 2015

Methods	Randomised double‐blind placebo‐controlled trial
Participants	Infertile women with PCOS 18 ‐ 40 years old (n = 64) Mean age: 25.1 ± 4.5 vs 25.4 ± 4.9 years, P = 0.85 Inclusion criteria: age between 18 and 40 years with PCOS according to Rotterdam criteria Exclusion criteria: elevated levels of prolactin, thyroid disorder, or Type 2 diabetes and congenital adrenal hyperplasia. In addition, all PCOS women had normal baseline renal function tests, bilirubin, and aminotransferases
Interventions	1. Selenium 200 ug: 1 tablet a day + metformin 500 mg: which was elevated in a stepwise manner during the first 3 weeks to incorporate the side effects until the participants were taking a total of 1500 mg a day (n = 32) 2. Placebo plus metformin: same dosage as above (n = 32) Treatment was for 8 weeks The trial ran from October 2014 to December 2014
Outcomes	Pregnancy rates (biochemical) Hormone levels
Notes	Conducted in Iran Trial was supported by an institutional grant. Clinical trial number: IRCT201412295623N33 Contact details: Dr Z Asemi; asemi_r@yahoo.com. Email sent 18th October 2016 regarding clinical pregnancy data and block size. No reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"patients with PCOS were randomly divided into 2 groups" "Patient allocation and block size were obtained using random number tables".
Allocation concealment (selection bias)	Low risk	"At the time of randomization,sequentially numbered, sealed envelopes were opened. Allocation to study group was concealed until the main analyses were completed".
Blinding (performance bias and detection bias) All outcomes	Low risk	Supplements and placebos were in the same form of package and the participants and researcher were not conscious of the content of the pack until the end of trial
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reasons and numbers for dropouts from each group were provided. ITT used in the analysis
Selective reporting (reporting bias)	Low risk	None noted
Other bias	Low risk	No other bias found