Morello 1999.

Methods	Randomised, double‐blind, placebo‐controlled, cross‐over, not enriched. No imputation method mentioned Titration over 2 days and adjusted thereafter until adequate pain relief obtained or limit of tolerability to maximum 1800 mg gabapentin or 75 mg amitriptyline daily, then stable dose for remainder of 6‐week period; 1‐week washout, then cross‐over
Participants	PDN. Pain duration > 3 months before treatment, no initial PI at inclusion N = 25 (19 completed 6 weeks with both study drugs) Mean age 60 years, 4% women Initial pain intensity mild/moderate
Interventions	Gabapentin 1800 mg daily (max) Amitriptyline 75 mg daily (max) Paracetamol allowed as rescue medication (max 1300 mg daily)
Outcomes	Pain relief at end of treatment (6‐point global score), complete or a lot Pain relief at end of treatment (6‐point global score), at least moderate Adverse events Withdrawal
Notes	Oxford Quality Score: R = 1, DB = 2, W = 1, Total = 4 No funding mentioned 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 (all except clinical research pharmacist remained blinded until study termination)
Blinding (performance bias and detection bias) All outcomes	Low risk	"all capsules were identical in taste, color, size, and shape"
Incomplete outcome data (attrition bias) Efficacy	Unclear risk	Imputation not mentioned
Size Efficacy	High risk	< 50 participants per treatment arm (25 randomised, 19 completed both periods