Iwaki 2020.

Study characteristics
Methods	Design: parallel Duration: 12 weeks Assessment: baseline and post‐intervention Country: Japan
Participants	Pain condition: pain in Parkinson's disease Population: adults with Parkinson's disease experiencing associated pain Minimum pain intensity: no Inclusion criteria Aged ≥ 20 with diagnosed Parkinson's disease Pain associated with Parkinson's disease Exclusion criteria Evidence of clinically significant disease Suicidal risk Total participants randomised: 47 Age in years (mean): 68.0 Gender: 25/47 were female Pain duration in years (mean): 2.3
Interventions	Placebo n = 23 Inert Matched dosing Duloxetine 40 mg n = 23 SNRI Fixed dose
Outcomes	Pain intensity Mood SAEs Withdrawal
Missing data methods	Not specified
Funding source	Pharmaceutical: funding was provided by Ehime University under a contract with Shionogi & Co. Ltd (pharmaceutical company).
Conflicts of interest	The authors have no COI to report
Notes
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 not specified
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	States double‐blinded but no information on appearance of study drugs
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Self‐reported outcomes from participants, but uncertain of blinding procedures
Incomplete outcome data (attrition bias) All outcomes	High risk	Much higher attrition in antidepressant arm than placebo. Unsure of imputation methods used Attrition Total: 9/46 (19.6%) Placebo: 2/23 (8.7%) Duloxetine 40 mg: 7/23 (30.4%)
Selective reporting (reporting bias)	Low risk	Outcomes match those in protocol
Other bias	Low risk	No other sources of bias were identified