Gould 2020.

Study characteristics
Methods	Design: parallel Duration: 12 weeks Assessment: baseline and post‐intervention Country: USA
Participants	Pain condition: low back pain Population: adults with low back pain Minimum pain intensity: ≥ 4 on 0‐10 VAS Inclusion criteria Aged 18‐70 Non‐specific low back with a duration of least ≥ 6 months ≥ 4 on a 0‐10 pain intensity VAS Exclusion criteria Current physical or mental health comorbidities Total participants randomised: 142 Age in years (mean, SD): 55.8 (11.7) Gender: 15/142 were female Pain duration in years (mean, SD): NR
Interventions	Placebo (benzotropine mesylate 0.125 mg) n = 33 Active placebo Fixed dose Desipramine n = 38 TCA Flexible dosage dependent upon patient metabolism Placebo (benzotropine mesylate 0.125 mg) + CBT n = 34 Combined intervention: active placebo pill + CBT Fixed dose of 0.125 mg 6 CBT appointments over the course of 8 weeks Desipramine + CBT n = 37 Combined intervention: TCA + CBT Flexible dosage dependent upon patient metabolism 6 CBT appointments over the course of 8 weeks
Outcomes	Pain intensity Physical function Moderate pain relief AEs SAEs Withdrawal
Missing data methods	ITT with LOCF
Funding source	Non‐pharmaceutical: VA Office of Research and Development Collaborator: University of California, San Diego
Conflicts of interest	The study authors have no conflicts of interest to declare
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	To minimise the risk of bias in treatment assignment, randomisation using a random number generator (www.randomizer.org) was conducted by a VA San Diego Healthcare System Clinical Research Pharmacy (author S.D.F.), who alone held the key
Allocation concealment (selection bias)	Unclear risk	Allocation procedures not specified
Blinding of participants and personnel (performance bias) All outcomes	High risk	Double‐blinding across all arms not possible due to the nature of CBT
Blinding of outcome assessment (detection bias) All outcomes	High risk	Self‐reported outcomes from unblinded participants
Incomplete outcome data (attrition bias) All outcomes	High risk	ITT with LOCF. Attrition unequal across arms Attrition Total: Placebo: 9/33 (27.3%) Desipramine 20‐60 mg: 11/38 (29.0%) Placebo + CBT: 7/34 (20.6%) Desipramine 20‐60 mg + CBT: 16/37 (43.2%)
Selective reporting (reporting bias)	Unclear risk	Mention in published paper that other outcomes were measured and reported in the protocol (which they don't seem to be) and that they were NR in the publication as it was not in keeping with the study hypothesis/aim
Other bias	Low risk	No other sources of bias were identified