Skljarevski 2009.

Study characteristics
Methods	Design: parallel Duration: 13 weeks Assessment: baseline and post‐intervention Country: USA and Argentina
Participants	Pain condition: low back pain Population: adult patients with non‐radicular chronic low back pain Minimum pain intensity: ≥ 4 on 0‐10 scale Inclusion criteria Clinical diagnosis of chronic low back pain with pain present on most days for ≥ 6 months Pain intensity ≥ 4 on 0‐10 scale Exclusion criteria Surgery or invasive procedures to treat low back pain Major depressive disorder Total participants randomised: 404 Age in years (mean, SD): 53.9 (14.1) Gender: 232/404 were female Pain duration in years (mean, SD): 11.7 (11.4)
Interventions	Placebo n = 117 Inert Identical in smell, taste and appearance to duloxetine Matched dosing across all arms Duloxetine 20 mg n = 59 SNRI Fixed dose Duloxetine 60 mg n = 116 SNRI Fixed dose Duloxetine 120 mg n = 112 SNRI Fixed dose
Outcomes	Pain intensity Sleep Physical function Quality of life Mood PGIC Moderate pain relief Substantial pain relief AEs SAEs Withdrawal
Missing data methods	ITT with LOCF
Funding source	Pharmaceutical: study design, funding and drugs were supplied by Eli Lilly and Company.
Conflicts of interest	Authors V. Skljarevski, M. Ossanna, H. Liu‐Seifert, Q. Zhang, A. Chappell, S. Iyengar and M. Detke are or were at the time of submission employees of Eli Lilly and Company and may be minor shareholders.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Patients were randomly assigned by a computer‐generated random sequence.
Allocation concealment (selection bias)	Low risk	Participants were allocated using an Interactive Voice Response System.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, identical study drugs, matched dosing
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Self‐reported outcomes by blinded participants
Incomplete outcome data (attrition bias) All outcomes	High risk	High attrition with significantly more missing in higher dose arm due to AEs. Use ITT and LOCF Attrition Total: 137/404 (33.9%) Placebo: 35/117 (29.9%) Duloxetine 20 mg: 16/59 (27.1%) Duloxetine 60 mg: 36/116 (31.0%) Duloxetine 120 mg: 50/112 (44.6%)
Selective reporting (reporting bias)	Low risk	Primary outcomes specified prospectively on clincialtrials.gov along with data not presented in paper
Other bias	Unclear risk	Some baseline differences in important variables: pain history but not imbalanced in a way which favours treatment