Ohta 2012.

Methods	12‐week multicentre, randomised, double‐blind, placebo‐controlled trial
Participants	Japanese participants with fibromyalgia according to ACR classification. Pain of ≥ 40/100 mm and pain diary score ≥ 4 on 11‐point numerical rating scale before randomisation N = 498 Mean age 48 years, 89% female Baseline mean pain: 6.5/10
Interventions	4 phases: 1‐week single‐blind run‐in period, 3‐week dose escalation, 12‐week fixed dose at 300 or 450 mg, 1‐week taper phase Pregabalin all doses, n = 250 Placebo, n = 248
Outcomes	Proportion of participants with ≥ 30% or ≥ 50% decrease in mean pain score PGIC (7‐point scale from very much improved to very much worse) between endpoint and baseline Adverse events Withdrawals
Notes	Pfizer sponsored Oxford Quality Score: R2, DB2, W1. Total = 5/5
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomisation control system (IMPALA), which provided subject randomisation numbers"
Allocation concealment (selection bias)	Low risk	"Randomisation control system (IMPALA), which provided subject randomisation numbers". Review authors judged this as low risk, assuming remote allocation
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Pregabalin and placebo capsules were prescribed by the investigator using blinded drug numbers issued by IMPALA" "identical placebo"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Pregabalin and placebo capsules were prescribed by the investigator using blinded drug numbers issued by IMPALA" "identical placebo"
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	LOCF imputation
Selective reporting (reporting bias)	Low risk	All relevant outcomes reported
Size	Low risk	> 200 participants per treatment arm (248 and 250)