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Joint-Specific Multidimensional Assessment of Pain
(J-MAP): Factor Structure, Reliability, Validity, and Responsiveness in Patients with Knee Osteoarthritis
KIMBERLY J. O'MALLEY, MARIA SUAREZ-ALMAZOR, JULIE ANIOL, PETER RICHARDSON, DAVID H. KUYKENDALL, J. BRUCE MOSELEY Jr, and NELDA P. WRAY
ABSTRACT. Methods. Developed using patient interviews, reviews of pain literature, and expert input from orthopedic surgeons, the final Joint-Specific Multidimensional Assessment of Pain (J-MAP) includes the 6-item Pain Sensory and the 4-item Pain Affect subscales. Scores on the J-MAP Pain Sensory and Affect subscales range from 0 to 100, with higher scores indicating more pain intensity and worse pain distastefulness, respectively. Following the assessment of the factor structure, patients' scores (n = 180) on the J-MAP subscales were converted to equal interval scores using Rasch analyses. A psychometric evaluation of the items and Rasch-calibrated scores was conducted and included an assessment of reliability, validity, and responsiveness for use with patients with radiographic knee osteoarthritis. Results. Evidence from the factor analyses showed that the J-MAP Pain Sensory and Affect items made up 2 distinct factors. Internal consistency estimates for the J-MAP subscales exceeded 0.85. The J-MAP subscales showed evidence for validity and were shown to be internally and externally responsive, demonstrating greater responsiveness than the Arthritis Impact Measurement Scale or the Medical Outcome Study Short Form-36 pain subscales. Finally, evidence was found supporting the J-MAP subscales' ability to distinguish target joint pain from pain emanating from other musculoskeletal conditions. Conclusion. The J-MAP is a reliable, valid, and responsive measure for assessing joint-specific pain at a single time point, or changes over time for one or a group of patients with knee osteoarthritis. With this initial evidence of its psychometric rigor, further testing of the measurement properties of the J-MAP in other joints and in other populations should be undertaken. (J Rheumatol 2003;30:534-43) Key Indexing Terms:
JOINT PAIN
From the Houston Center for Quality of Care and Utilization Studies, Houston VA Medical Center (VAMC), and Section of Health Services Research, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA; International Survey Research, London, UK; and the Department of Orthopedic Surgery, Baylor College of Medicine. Supported with resources and the use of facilities at the Houston Center for Quality of Care and Utilization Studies, Houston Veterans Affairs Medical Center, and by grant H-1639 from the US Department of Veterans Affairs. K.J. O'Malley, PhD, Psychometrician, Assistant Professor; M. Suarez-Almazor, MD, PhD, Rheumatologist, Professor; J. Aniol, PhD, Clinical Psychologist, Instructor; P. Richardson, PhD, Statistical Programmer, Houston Center for Quality of Care and Utilization Studies, Houston VAMC, and Section of Health Services Research, Department of Medicine, Baylor College of Medicine; D.H. Kuykendall, PhD, Psychometrician, Director of Research and Project Director, International Survey Research, London, UK; J.B. Moseley Jr, MD, Clinical Associate Professor, Houston Center for Quality of Care and Utilization Studies, Houston VAMC, and Section of Health Services Research, Department of Medicine; N.P. Wray, MD, MPH, Senior Researcher, Chief of the Section of Health Services Research, Professor, Department of Orthopedic Surgery, Baylor College of Medicine. Address reprint requests to Dr. K.J. O'Malley, VA Medical Center (152), 2002 Holcombe Boulevard, Houston, TX 77030. E-mail: komalley@bcm.tmc.edu Submitted February 11, 2002; revision accepted August 28, 2002. |