Objectives: This study examined the time course for minimal clinically significant improvement in pain severity during the initial 12 weeks of treatment in patients with fibromyalgia taking duloxetine.
Methods: Four double-blind, placebo-controlled trials of duloxetine were pooled. Patients received duloxetine 60 mg/d, 120 mg/d, or placebo. Clinically significant treatment response (≥30% reduction in pain severity on the 24-hour average pain severity of the Brief Pain Inventory scale) was assessed over 12 weeks.
Results: At endpoint, 46.9% of duloxetine 60-mg-, 48.6% of duloxetine 120-mg-, and 32.1% of placebo-treated patients (P<0.001 for both doses) had ≥30% improvement on average pain from baseline. The probabilities of achieving ≥30% response at Weeks 1, 2, 4, 8, and 12 among duloxetine 60-mg-treated patients were 27%, 44%, 45%, 47%, and 49%, respectively, and among duloxetine 120-mg-treated patients were 35%, 43%, 53%, 53%, and 51%, respectively (P<0.01 vs. placebo at each week, for both doses). Among patients who did not respond by Weeks 1, 2, 4, and 8, the percentages of duloxetine 60-mg-treated patients who achieved a response by the endpoint of the study were 36.9%, 29.8%, 28.9%, and 26.9%, respectively.
Discussion: This article examines the time course for minimal clinically significant improvement in pain severity in duloxetine-treated patients with fibromyalgia. It provides information about continued treatment in patients who do not initially respond to duloxetine. This information could potentially help physicians facing clinical decisions about management of fibromyalgia with duloxetine.
*University of Alabama at Birmingham, Birmingham, AL
†Lilly Research Laboratories, Indianapolis, IN
‡Swedish Medical Center, University of Washington School of Medicine, Seattle, WA
Reprints: Madelaine M. Wohlreich, MD, Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285 (e-mail: firstname.lastname@example.org).
Received for publication April 20, 2009; revised December 10, 2009; accepted January 18, 2010
This work was sponsored by Eli Lilly and Company and Boehringer Ingelheim GmbH. Conflicts of interest: Drs Wohlreich, Wang, Gaynor, Robinson, and D'Souza are employees and stockholders of Eli Lilly and Company. Dr Bradley is a consultant for Eli Lilly, Pfizer, and Forest; has received grant/research support from the National Institutes of Health, the Agency for Healthcare Research and Quality, Eli Lilly, Pfizer, and the American Fibromyalgia Syndrome Association; has received honoraria from Eli Lilly, Pfizer, Forest, and the Society for Women's Health Research; is a member of the speakers/advisory board for Eli Lilly and Company; and has received royalties from UpToDate Rheumatology. Dr Mease has received grants/research support from Eli Lilly and Company, Pfizer, Inc, Cypress Bioscience, Forest, Allergan, Fralex, and Boehringer Ingelheim; he has been a consultant for Eli Lilly and Company, Pfizer, Inc, UCB, Cypress Bioscience, Forest, Allergan, Fralex, Boehringer Ingelheim, Pierre Fabre, and Wyeth; and he is on the Speakers Bureau of Eli Lilly and Company, and Pfizer, Inc.