Majdinasab 2019.

Study characteristics
Methods	Design: parallel Duration: 8 weeks Assessment: baseline and post‐intervention Country: Iran
Participants	Pain condition: painful diabetic peripheral polyneuropathy Population: adults with painful diabetic peripheral polyneuropathy Minimum pain intensity: ≥ 40 on 0‐100 VAS Inclusion criteria Aged between 18‐75 Painful diabetic peripheral poly‐neuropathy from 1 month to 5 years ≥ 40 on 0‐100 pain intensity VAS Exclusion criteria Severe illness in vital organs Using medication to treat pain Total participants randomised: 104 Age in years (mean): 60.3 Gender: 50/104 were female Pain duration in years (mean): 3.75
Interventions	Gabapentin 300‐900 mg n = 52 Anticonvulsant Flexible dose depending on tolerability Identical appearance to duloxetine Duloxetine 30‐60 mg n = 52 SNRI Flexible dose depending on tolerability
Outcomes	Pain intensity Sleep AEs Withdrawal
Missing data methods	NR
Funding source	Non‐pharmaceutical: "This study was funded by Ahvaz Jundishapur University of Medical Sciences (grant number IR.AJUMS.REC.1395.78)"
Conflicts of interest	Dr Nastaran Majdinasab, Dr Hossein Kaveyani, and Dr Mojgan Azizi have received research grants from Ahvaz Jundishapur University of Medical Sciences (grant number IR.AJUMS.REC.1395.78). The authors report no other conflicts of interest in this work.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomised using the 4 block randomised method (equalised 4‐blocks).
Allocation concealment (selection bias)	Low risk	"The medications of this study were first made similar to each other by a doctor who had no role in the collection and analysis of data and then sufficient amounts were packed into packets A and B and were given to the researcher."
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Used identical drugs and placebos and packets but: "Before the commencement of the study, the side effects of the medications were explained to the patients " could then allow participants to know what they're experiencing and which medication it comes from.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Self‐reported outcomes from participants, but unsure of blinding
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Method of missing data not specified Attrition Total: 16/104 (15.4%) Gabapentin 300‐900 mg: 11/52 (21.2%) Duloxetine 30‐60 mg: 5/52 (9.6%)
Selective reporting (reporting bias)	Unclear risk	Protocol registered retrospectively
Other bias	Unclear risk	Errors in publication between tables