Maarrawi 2018.

Study characteristics
Methods	Design: parallel Duration: 8 weeks Assessment: baseline and post‐intervention Country: Lebanon
Participants	Pain condition: chronic neck pain Population: people with chronic neck pain Minimum pain intensity: no Inclusion criteria Chronic neck pain for > 15 days/month during at least 3 consecutive months Exclusion criteria Physical and mental health comorbidities Total participants randomised: 332 Age in years (mean, SD): 44.23 (11.39) Gender: 190/332 were female Pain duration in years (mean, SD): 15.4 (4.86)
Interventions	Placebo n = 166 Inert Identical appearance and matched dosing Amitriptyline 5 mg n = 166 TCA Fixed dose, no titration
Outcomes	Pain intensity
Missing data methods	Completer‐only analysis
Funding source	Non‐pharmaceutical: "This study was supported by the Council of Research of the Saint Joseph University of Beirut – Lebanon (FM201)"
Conflicts of interest	No conflicts of interest
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomised via the block randomisation method, computer‐generated via www.randomization.com)
Allocation concealment (selection bias)	Low risk	Randomisation was centralised by a staff nurse (who had never seen the patient) not otherwise involved in the study and noted the group of each participant next to the number assigned to him. The same staff nurse delivered the corresponding medication to each patient.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, study drugs were identical with matched dosing schedule
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Self‐reported outcomes from blinded participants
Incomplete outcome data (attrition bias) All outcomes	High risk	Completer‐only analysis. Withdrawal rate rate was ~17% Attrition Total: 58/332 (17.5%) Placebo: 25/166 (15.1%) Amitriptyline 5 mg: 33/166 (19.9%)
Selective reporting (reporting bias)	Low risk	All outcomes match up with those prospectively registered on clinicaltrials.gov
Other bias	Unclear risk	Unclear reporting in the publication, especially in relation to sample size and withdrawal