Response to duloxetine in patients with knee pain due to osteoarthritis: an exploratory post hoc analysis of a Japanese Phase III randomized study
Received 1 June 2018
Accepted for publication 21 September 2018
Published 26 October 2018 Volume 2018:11 Pages 2603—2616
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 4
Editor who approved publication: Dr E Alfonso Romero-Sandoval
Naohiro Itoh,1 Toshinaga Tsuji,1 Mitsuhiro Ishida,2 Toshimitsu Ochiai,3 Shinichi Konno,4 Yuji Uchio5
1Medical Affairs Department, Shionogi & Co. Ltd, Osaka, Japan; 2Clinical Development Department, Shionogi & Co. Ltd, Osaka, Japan; 3Biostatistics Center, Shionogi & Co. Ltd, Osaka, Japan; 4Department of Orthopaedic Surgery, Fukushima Medical University, Fukushima, Japan; 5Department of Orthopaedic Surgery, Shimane University School of Medicine, Shimane, Japan
Purpose: To assess whether patients with knee osteoarthritis pain who have early pain reduction or treatment-related adverse events of special interest (TR-AESIs; constipation, decreased appetite, malaise, nausea, somnolence, thirst) with duloxetine treatment are more likely to have later improvements in pain and quality of life (QOL) relative to placebo than patients without these early indicators.
Patients and methods: This was a post hoc analysis of 14-week randomized trial of Japanese patients with knee osteoarthritis pain (Brief Pain Inventory [BPI]-Severity average pain score ≥4) receiving duloxetine 60 mg/day (n=177 analyzed) or placebo (n=176). Primary trial outcome was change from baseline in BPI-Severity average pain at Week 14. Subgroups included early pain reduction (≥30%, 10%–30%, or <10% decrease in BPI-Severity average pain at Week 4) and early TR-AESIs (with/without TR-AESIs by Week 2). Measures included changes from baseline in BPI-Severity average pain, QOL (BPI-Interference, Western Ontario and McMaster Universities Osteoarthritis Index), Patient Global Impression of Improvement (PGI-I), and response rate (proportion achieving ≥30% or ≥50% pain reduction at Week 14).
Results: The ≥30% early pain reduction subgroup (n=93) had significantly greater improvements in pain, QOL, and PGI-I and higher ≥30% and ≥50% response rates than placebo; the 10%–30% (n=45) and the <10% (n=33) pain reduction subgroups did not show the same (except 10%–30% group: PGI-I at Week 10 and some QOL at Weeks 10 and/or 14). Both TR-AESI subgroups (with, n=52; without, n=125) had significantly greater improvements in pain, PGI-I, and most QOL measures and higher response rates than placebo.
Conclusion: Early efficacy responses to duloxetine treatment, but not early TR-AESIs, may predict later pain reduction and QOL improvements in Japanese patients with knee osteoarthritis pain.
ClinicalTrials. gov: NCT02248480.
Keywords: Brief Pain Inventory, responder analysis, WOMAC
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