NCT00401830.

Methods	Multicentre, randomised, double‐blind, placebo‐controlled, parallel, no enrichment. LOCF imputation 12‐week treatment period: 4‐week titration from 100 mg/d to 400 mg/d, increasing by 100 mg/d at weekly intervals; 8‐week maintenance
Participants	Fibromyalgia (ACR criteria), duration not given. Age 18 to 65 years (mean 50 years), 93% female. Baseline pain ≥ 5/10 on a NRS N = 159
Interventions	Lacosamide 400 mg/d, n = 78 Placebo, n = 81 Medication given as 2 equally‐divided doses
Outcomes	Change in pain score (11‐point NRS) PGIC (7‐point scale) Adverse events Withdrawals
Notes	Oxford Quality Score: R = 1, DB = 2, W = 1. Total = 4/5
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	Imputation using last observation carried forward for efficacy data, but not used. ITT for PGIC, adverse events and withdrawals
Selective reporting (reporting bias)	Low risk	Expected outcomes were reported in some way, although not necessarily as our preferred outcome
Other bias	Unclear risk	Group sizes 50 to 200
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"matching placebo tablet"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Patient reported and patient blinded