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Pain Research and Treatment
Volume 2012, Article ID 296710, 6 pages
Research Article

Efficacy and Safety of Duloxetine in Patients with Chronic Low Back Pain Who Used versus Did Not Use Concomitant Nonsteroidal Anti-Inflammatory Drugs or Acetaminophen: A Post Hoc Pooled Analysis of 2 Randomized, Placebo-Controlled Trials

1Lilly Research Laboratories, Eli Lilly and Company, Drop Code 1542, Indianapolis, IN 46285, USA
2Lilly USA, LLC., Drop Code 4133, Indianapolis, IN 46285, USA

Received 12 October 2011; Revised 12 December 2011; Accepted 6 January 2012

Academic Editor: Mario I. Ortiz

Copyright © 2012 Vladimir Skljarevski et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This subgroup analysis assessed the efficacy of duloxetine in patients with chronic low back pain (CLBP) who did or did not use concomitant nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen (APAP). Data were pooled from two 13-week randomized trials in patients with CLBP who were stratified according to NSAID/APAP use at baseline: duloxetine NSAID/APAP user ( 𝑛 = 1 3 7 ), placebo NSAID/APAP user ( 𝑛 = 8 2 ), duloxetine NSAID/APAP nonuser ( 𝑛 = 2 0 6 ), and placebo NSAID/APAP nonuser ( 𝑛 = 1 5 6 ). NSAID/APAP users were those patients who took NSAID/APAP for at least 14 days per month during 3 months prior to study entry. An analysis of covariance model that included therapy, study, baseline NSAID/APAP use (yes/no), and therapy-by-NSAID/APAP subgroup interaction was used to assess the efficacy. The treatment-by-NSAID/APAP use interaction was not statistically significant ( 𝑃 = 0 . 3 1 ) suggesting no substantial evidence of differential efficacy for duloxetine over placebo on pain reduction or improvement in physical function between concomitant NSAID/APAP users and non-users.