Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


The Efficacy and Safety of Duloxetine Treatment in Older Patients with Osteoarthritis Knee Pain: A Post Hoc, Subgroup Analysis of Data From 2 Placebo-Controlled Trials.

Micca1,  Joseph L., Risser2,  Richard C., Ahl2,  Jonna, Wohlreich2,  Madelaine M.

Patient Centered Healthcare, Altanta, GA
Lilly USA, Indianapolis, IN

Background/Purpose:

Osteoarthritis (OA) of the knee is common in the elderly and a leading cause of disability. Alleviation of pain symptoms should be the focus of knee OA treatment. The purpose of this study was to examine the efficacy and safety of duloxetine (DLX) treatment in older aged patients with OA knee pain.

Methods:

This was a post-hoc analysis of data from two 3-month randomized double-blind placebo-controlled trials in patients with symptomatic knee OA. In both studies, patients were randomized to DLX 60mg QD vs. placebo for 7 weeks. For the remaining 6 weeks, in Study I, DLX patients were re-randomized to receive either DLX 60 mg QD or 120 mg QD. In Study II, only DLX non-responders (defined as <30% improvement from baseline on Brief Pain Inventory 24-h average pain item score) had their dose increased to 120 mg. For each study, patients were stratified according to age: <65 (younger) and >= 65 years (older). Dosing arms for each age group were: DLX 60 mg for patients who remained on this dose, and DLX 120 for patients who had their dose increased, and placebo. Pain severity (0–10) was assessed daily and recorded in patient diaries. Change in weekly average pain was analyzed with a mixed-models repeated measures model including terms up to and including the 3-way interaction between treatment, age group, and week, which assesses differential treatment effects between age groups over time. Treatment-emergent adverse events (TEAEs) were compared between treatments and subgroups using a logistic regression model including the terms up to and including the interaction between treatment and age group, which assesses the differential treatment effects between age groups.

Results:

Across both studies, average age in years was 56 for younger subgroup and 72 for older subgroup. Average pain duration in younger and older groups was 7 and 10 years, respectively, and average baseline pain score was 6 in both age groups. The older subgroup included: DLX 60, n=68; DLX 120, n=35; PLA, n=136; and the younger subgroup included: DLX 60, n=95; DLX 120, n=41; PLA, n=154. After 13 weeks treatment, in Study I, there was significantly greater pain reduction in older patients with DLX 60 mg and 120 mg vs. PLA (-3.3 (60 mg) and -4.1 (120 mg) vs. -2.0; both p<.01). Among younger patients, those receiving DLX 120 had significantly greater pain reduction vs. PLA (-3.1 vs. -2.2; p=.03); improvement in pain did not differ from PLA in patients receiving DLX 60 mg. In Study II, all patients receiving DLX 60 mg had significantly greater improvement in pain vs. PLA (older: -3.2 vs. -1.8, p<.01; younger: -3.0 vs. -2.0, p<.01); improvement in pain did not differ from PLA in patients receiving DLX 120 mg. Among TEAEs with frequency >= 2% for DLX, only dizziness showed significant treatment by subgroup interaction (p =.022), with greater incidence over placebo in younger patients (6.6% vs 0.6%, p =.024) but not in the older patients (1.0% vs 3.2%, p =.292).

Conclusion:

In older patients, duloxetine 60 mg/day for the treatment of OA knee pain was efficacious and well tolerated.

To cite this abstract, please use the following information:
Micca, Joseph L., Risser, Richard C., Ahl, Jonna, Wohlreich, Madelaine M.; The Efficacy and Safety of Duloxetine Treatment in Older Patients with Osteoarthritis Knee Pain: A Post Hoc, Subgroup Analysis of Data From 2 Placebo-Controlled Trials. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1094
DOI:

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