Wang 2009.

Methods	Randomised, placebo‐controlled
Participants	18 adult men and women with RLS who had ferritin 15‐75 ng/mL and IRLS scores >= 11
Interventions	Intervention: ferrous sulfate 325 mg bid in non‐descript capsules Placebo: lactose, appearance‐matched Study drug continued for 12 weeks
Outcomes	IRLS (BL, 6 weeks, 12 weeks), ferritin (BL, 6 weeks, 12 weeks), single question on change in quality of life at 12 weeks (improved, same, worsened), compliance at 6 and 12 weeks (by manual pill count)
Notes	Authors raise issue of iron causing stool discolouration and therefore inadvertent unblinding, although this is speculative
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Used randomly generated sequenced number programme
Allocation concealment (selection bias)	Low risk	Independent investigative pharmacist performed randomisation and kept randomisation code in locked cabinet
Blinding (performance bias and detection bias) All outcomes	Low risk	Matched capsules of placebo and iron; investigators and participants blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants who were randomised completed the study
Selective reporting (reporting bias)	Unclear risk	No study protocol available
Other bias	Low risk	No other risks identified

BL: baseline
 CGI‐I: Clinical Global Impression of Improvement
 ESRD: end‐stage renal disease
 ESS: Epworth Sleepiness Scale
 FSS: fatigue severity scale
 IRLS: International RLS Study Group severity scale
 IRLSSG: International Restless Legs Syndrome Study Group
 IV: intravenous
 MOS: medical outcomes of sleep
 MRI: magnetic resonance imaging
 PGI‐C: Patient Global Impression of Change

PLMS: periodic limb movements of sleep
 PSG: polysomnography
 PSQI: Pittsburgh Sleep Quality Index
 RLS: restless legs syndrome
 RLS‐QoL: RLS quality of life scale
 SF‐36: Short‐form‐36
 VAS: visual analogue scale