Arnold 2014.

Methods	13‐week multicentre, controlled‐release, double‐blind, placebo‐controlled, EERW trial
Participants	Fibromyalgia according to ACR classification and pain diary score ≥ 4 on 11‐point numerical rating scale N = 441 entered titration phase, 121 randomised to double‐blind phase Mean age 50 years, 91% female, 90% white Baseline mean pain score: 6.8/10
Interventions	4 phases: 1) baseline (1 week), 2) single‐blind (participants were blinded) treatment (6 weeks), 3) double‐blind treatment (13 weeks), and 4) a double‐blind taper period (1 week) Pregabalin controlled release 330 to 495 mg daily, n = 63 Placebo, n = 58
Outcomes	PI on an 11‐point numerical rating scale, using daily pain diary 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)	Unclear risk	Not described, "randomly assigned"
Allocation concealment (selection bias)	Low risk	"telephone using the Interactive Voice Recognition System (IVRS)"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Stated to be double blind. Used a matching placebo
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Stated to be double blind. Used a matching placebo
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants included in analysis
Selective reporting (reporting bias)	Low risk	All relevant outcomes reported
Size	Unclear risk	50 to 199 participants per treatment arm (58, 63)