Gorson 1999.

Methods	Randomised, double‐blind, placebo‐controlled, cross‐over, not enriched. No imputation method mentioned Titration over 3 days to 900 mg, then fixed dose for remainder of 6‐week period; 3 week washout, then cross‐over
Participants	PDN 1‐5 years, pain ≥ moderate for over 3 months. Pain intensity at randomisation ≥ 40/100 N = 40 Mean age 62 years, 23% women Initial pain intensity not reported
Interventions	Gabapentin 900 mg, n = 19 (first phase) Placebo, n = 21 (first phase) Medication for diabetes control remained stable during study. Stable doses of NSAID or narcotics allowed
Outcomes	Pain relief at end of treatment (4‐point global score) moderate or excellent Adverse events
Notes	Oxford Quality Score: R = 1, DB = 1, W = 0, Total = 3 Sponsored by Warner Lambert/Parke‐Davis Note: no separate data for first period, small group sizes, non standard global scale
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not reported
Incomplete outcome data (attrition bias) Efficacy	Unclear risk	Imputation not mentioned
Size Efficacy	High risk	< 50 participants per treatment arm (19, 21)