Methods: This was a Phase 3, randomized, double-blind, placebo-controlled, parallel-group study (duloxetine N=162, placebo N=168). The co-primary efficacy outcome measures were reduction of pain severity using the average pain item of the Brief Pain Inventory (BPI), and patient-reported improvement using the Patient’s Global Impressions of Improvement (PGI-I) questionnaire. Secondary measures included Fibromyalgia Impact Questionnaire [FIQ] total score, mean tender-point pain thresholds, Multidimensional Fatigue Inventory (MFI), Clinical Global Impressions of Severity (CGI-Severity), Sheehan Disability Scale [SDS] Global Functional Impairment Total Score, 36-item Short-Form Health Survey (SF-36) scores, and EuroQoL Questionnaire-5 Dimension [EQ-5D]. Safety and tolerability measures were also assessed.
Results: There were no statistically significant differences between duloxetine- and placebo-treated patients for the primary efficacy measures of change in the BPI average pain from baseline to endpoint (least-squares [LS] mean changes of -1.62 vs -1.13, P=.053) and the PGI-I at endpoint (LS means of 3.42 vs 3.73, P=.064). Duloxetine-treated patients improved significantly more than placebo-treated patients on the Mental Component Summary of the SF-36 scale (LS mean changes of 3.37 vs 0.79, P≤.05). There was also a significant difference between duloxetine- and placebo-treated patients in the SF-36 Mental Health score (LS mean changes of 6.63 vs 1.19, P≤.01), CGI-S scale (LS mean changes of -0.58 vs -0.28, P≤.01), and MFI-Mental Fatigue Scale (LS mean changes of -0.99 vs -0.02, P≤.05). Nausea was the most common TEAE in the duloxetine group (duloxetine 26.5%, placebo 9.5%, P≤.001). Overall discontinuation rates were similar between treatment groups (duloxetine 37.7%, placebo 38.7%). Discontinuation due to lack of efficacy was significantly higher in the placebo group (duloxetine 7.4%, placebo 14.9%, P≤.05). There were significant differences between groups for change in diastolic pressure (duloxetine [mm Hg] 1.68, placebo -1.46, P≤.01) and pulse rate (duloxetine [bpm] 1.07, placebo -1.64, P≤.05).
Conclusions: In patients with fibromyalgia syndrome, 60-120 mg/day of duloxetine did not demonstrate superiority to placebo for the co-primary outcomes of average pain severity and self-reported global improvement, but it did demonstrate significant improvement compared with placebo based on some secondary measures.
A. Chappell, Eli Lilly and Company, 1; Eli Lilly and Company, 1; Eli Lilly and Company, 3; L. Bradley, Eli Lilly and Company, 2; C. Wiltse, Eli Lilly and Company, 1; Eli Lilly and Company, 1; Eli Lilly and Company, 3; D.N. D'Souza, Eli Lilly and Company, 1; Eli Lilly and Company, 1; Eli Lilly and Company, 3; M. Spaeth, None.
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