Vrethem 1997.

Study characteristics
Methods	Design: cross‐over Duration: each cross‐over period lasted 4 weeks Assessment: baseline, mid‐intervention (8‐14 days), post‐cross‐over period Country: Sweden
Participants	Pain condition: polyneuropathy (diabetic and non‐diabetic) Population: adults with painful polyneuropathy. 19 had diabetic polyneuropathy, 18 had non‐diabetic polyneuropathy Minimum pain intensity: no Inclusion criteria Daily moderate or severe polyneuropathic pain for at least 6 months Exclusion criteria Patients with other neurologic diseases were excluded. Total participants randomised: 37 Age in years (range): 35‐83 Gender: 19/37 were female Pain duration in years (range): 6‐168
Interventions	Placebo Inert Identical appearance Double‐dummy design Amitriptyline 75 mg TCA Fixed dose, forced titration Maprotiline 75 mg TeCA Fixed dose, forced titration
Outcomes	Pain intensity
Missing data methods	NR
Funding source	Non‐pharmaceutical: This work was supported by grants from The Medical Research Council, project no. 9058, The Swedish Association of Neurologically Disabled, The County Council of Ostergotland, and The University Hospital of Linkoping
Conflicts of interest	NR
Notes	This study reported results separately for participants with and without neuropathic pain caused by diabetes. Therefore, in the NMA we separated the study into 2 to include the 2 sets of results for both populations.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation methods NR
Allocation concealment (selection bias)	Unclear risk	Allocation procedures NR
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, identical study drugs, double‐dummy design
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Self‐reported outcomes from blinded participants
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No clear information regarding withdrawal, no information regarding missing data methods Attrition Total: 4/37 (10.8%) Attrition per arm NR
Selective reporting (reporting bias)	Unclear risk	No protocol or trial registration found
Other bias	Low risk	No other sources of bias were identified