Efficacy of long-term milnacipran treatment in patients meeting different thresholds of clinically relevant pain relief: subgroup analysis of a randomized, double-blind, placebo-controlled withdrawal study

Philip J Mease,1 Daniel J Clauw,2 Joel M Trugman,3 Robert H Palmer,3 Yong Wang3 1Swedish Medical Center and University of Washington, Seattle, WA, USA; 2Chronic Pain and Fatigue Research Center, University of Michigan Health System, Ann Arbor, MI, USA; 3Forest Research Institute, Jersey City, NJ, USA Background: Fibromyalgia patients from a long-term, open-label study of milnacipran (50–200 mg/day) were eligible to participate in a 12-week, randomized, placebo-controlled withdrawal study. The withdrawal study evaluated loss of therapeutic response in patients who achieved ≥50% pain improvements after receiving up to 3.25 years of milnacipran. This post-hoc analysis investigated whether patients who met lower thresholds of pain improvement also experienced worsening of fibromyalgia symptoms upon treatment withdrawal. Method: Among patients who received milnacipran ≥100 mg/day during the long-term study, three subgroups were identified based on percentage of pain reduction at randomization: ≥50% (protocol-defined "responders"; n=150); ≥30% to