Preliminary Development of a Responder Index for Chronic Low Back Pain

LEE S. SIMON, CHRISTOPHER EVANS, NATHANIEL KATZ, CLAIRE BOMBARDIER, CHRISTINE WEST, JEFFERY ROBBINS, CATHERINE COPLEY-MERRIMAN, J. MARKMAN, and JOHN H. COOMBS

ABSTRACT.

Objective. One of the greatest obstacles to identifying the most effective therapy for chronic low back pain (CLBP) is the lack of standardized outcome measures for assessing treatment effect in clinical trials. The aim of the OMERACT Special Interest Group was to discuss the development and validation of a preliminary responder index in CLBP.

Methods. Patient data from 5 clinical trials of celecoxib and valdecoxib use in CLBP were used to assess the reliability and validity of multiple items in the outcome domains of pain, functioning, and overall impression of health. Candidate preliminary responder indices were selected on the basis of effect size, high chi-square test values, and a placebo response rate ≤ 25%.

Results. Candidate indices comprised improvements in single outcome measures and combinations of improvements and/or avoidance of worsening in multiple measures. The preliminary choice for the responder index was at least 30% improvement in pain, with an improvement of at least 30% in patient global assessment and no worsening in function.

Conclusion. Further studies are needed to refine a responder index for CLBP trials that is clinically relevant, reliable, and easy to administer for standardizing assessments across clinical trials. (J Rheumatol 2007;34:1386-91)

Key Indexing Terms:

LOW BACK PAIN
OUTCOME MEASURES
CLINICAL RESPONDER CRITERIA
INSTRUMENTS

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From Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; MAPI Values, Boston, Massachusetts, USA; Analgesic Research, Newton, Massachusetts, USA; University of Toronto, Toronto, Ontario, Canada; Pfizer Inc., Ann Arbor, Michigan, USA; and the University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.

Supported by Pfizer, Inc.

L.S. Simon, MD, Harvard Medical School, Beth Israel Deaconess Medical Center; C. Evans, PhD, MAPI Values; N. Katz, MD, Analgesic Research; C. Bombardier, MD, University of Toronto; C. West, PhD; J. Robbins, MS; C. Copley–Merriman, MS, MBA; J. Markman, MD; J.H. Coombs, PharmD, Pfizer Inc.

Address reprint requests to Dr. L.S. Simon, Harvard Medical School, Beth Israel Deaconess Medical Center, 35 Oldham Road, West Newton, MA 02465. E-mail: lsimon@bidmc.harvard.edu

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