Miki 2016.

Study characteristics
Methods	Design: parallel Duration: 12 weeks Assessment: baseline and post‐intervention Country: Japan
Participants	Pain condition: fibromyalgia Population: Japanese adults aged between 20‐64 with fibromyalgia Minimum pain intensity: ≥ 40 on 0‐100 scale Inclusion criteria Japanese adults aged between 20 and 64 years who met the ACR diagnostic criteria for fibromyalgia Pain intensity ≥ 40 on 0‐100 scale Exclusion criteria Physical and mental health comorbidities Total participants randomised: 430 Age in years (mean): 45.2 Gender: 347/430 were female Pain duration in years (mean): 4.4
Interventions	Placebo n = 215 Inert Identical appearance to mirtazapine with matched dosing Mirtazapine 30 mg n = 215 NaSSA Fixed dose
Outcomes	Pain intensity Mood Quality of life Physical function Moderate pain relief Substantial pain relief AEs Severe AEs Withdrawal
Missing data methods	NR
Funding source	Pharmaceutical: funded by Meiji Seika Pharma Co, Ltd.
Conflicts of interest	The authors have no conflicts of interest to declare. K. Miki, M. Murakami, H. Oka, K. Osada received honorarium from Meiji Seika Pharma Co, Ltd. K. Onozawa and S. Yoshida are employees of Meiji Seika Pharma Co, Ltd.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The randomisation was done by a computer‐generated allocation sequence
Allocation concealment (selection bias)	Low risk	Allocation was delivered by a telephone randomisation service (randomisation manager) not involved in participant recruitment or treatment to ensure allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, identical study drugs with matched dosing
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	ITT but methods not specified Attrition Total: 48/430 (11.2%) Placebo: 23/215 (10.7%) Mirtazapine 30 mg: 25/215 (11.6%)
Selective reporting (reporting bias)	Unclear risk	Protocol published prospectively but no outcomes specified apart from "amount of change from baseline"
Other bias	High risk	Pain intensity change scores reported in the paper do not seem to be correct. When calculated into SMD, an SMD of over 4 resulted, which is improbable. Emailed study authors for clarification but no response, and no correction found.