Irving 2009.

Methods	Multicentre, randomised, double‐blind, placebo‐controlled, parallel groups, partial enrichment, LOCF, extended‐release formulation Gradual titration to 1800 mg over 2 weeks, then stable for 2 weeks (4 weeks in total)
Participants	PHN. Pain > 3 months after healing of skin rash, PI at randomisation ≥ 4/10 N = 158, mean age 70 years, 53% women Initial average daily pain score 6.5/10
Interventions	Gabapentin ER 1800 mg daily, n = 55 Gabapentin ER 1800 mg daily in split doses, n = 52 Placebo, n = 51 Rescue with paracetamol up to 4000 mg daily, or paracetamol plus hydrocodone 500 mg/5 mg up to 8 tablets daily
Outcomes	≥ 50% reduction in pain score ≥ 30% reduction in pain score PGIC much or very much improved Adverse events Withdrawals
Notes	Oxford Quality Score: R = 2, DB = 2, W = 1, Total = 5 Sponsored by Depomed
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated list
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Low risk	Double‐dummy method
Incomplete outcome data (attrition bias) Efficacy	Unclear risk	LOCF
Size Efficacy	Unclear risk	50‐200 participants per treatment arm (51‐55)