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Estimation of minimum clinically important difference for pain in fibromyalgia
Author(s) -
Mease Philip J.,
Spaeth Michael,
Clauw Daniel J.,
Arnold Lesley M.,
Bradley Laurence A.,
Russell I. Jon,
Kajdasz Daniel K.,
Walker Daniel J.,
Chappell Amy S.
Publication year - 2011
Publication title -
arthritis care and research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.032
H-Index - 163
eISSN - 2151-4658
pISSN - 2151-464X
DOI - 10.1002/acr.20449
Subject(s) - fibromyalgia , minimal clinically important difference , brief pain inventory , medicine , physical therapy , placebo , pain scale , duloxetine , randomized controlled trial , chronic pain , alternative medicine , pathology
Objective To estimate the minimum clinically important difference (MCID) for several pain measures obtained from the Brief Pain Inventory (BPI) for patients with fibromyalgia. Methods Data were pooled across 12‐week treatment periods from 4 randomized, double‐blind, placebo‐controlled studies designed to evaluate the safety and efficacy of duloxetine for the treatment of fibromyalgia. Each study enrolled subjects with American College of Rheumatology–defined fibromyalgia who presented with moderate to severe pain. The MCIDs for the BPI average pain item score and the BPI severity score (the mean of the BPI pain scale values: right now, average, least, and worst) were estimated by anchoring against the Patient's Global Impressions of Improvement scale. Results The anchor‐based MCIDs for the BPI average pain item and severity scores were 2.1 and 2.2 points, respectively. These MCIDs correspond to 32.3% and 34.2% reductions from baseline in scores. Conclusion In these analyses, the MCIDs for several pain measures obtained from the BPI were similar (∼2 points) and corresponded to a 30–35% improvement from baseline to end point. These findings may be beneficial for use in designing clinical trials in which the BPI is used to evaluate improvements in pain severity.