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Severity of Joint Pain and Kellgren-Lawrence Grade at Baseline Are Better Predictors of Joint Space Narrowing Than Bone Scintigraphy in Obese Women with Knee Osteoarthritis
STEVEN A. MAZZUCA, KENNETH D. BRANDT, DONALD S. SCHAUWECKER, BARRY P. KATZ, JOAN M. MEYER, KATHLEEN A. LANE, JOHN D. BRADLEY, STEVEN T. HUGENBERG, FREDERICK WOLFE, LARRY W. MORELAND, LOUIS W. HECK, DAVID E. YOCUM, THOMAS J. SCHNITZER, LEENA SHARMA, SUSAN MANZI, and CHESTER V. ODDIS
ABSTRACT. Methods. Subjects (174 obese women, 45–64 yrs of age, with unilateral knee OA) were a subset of a larger cohort who participated in a placebo controlled trial of a disease modifying OA drug. Uptake of technetium medronate (99mTc-MDP) in anteroposterior (AP) and lateral views of a late-phase bone scan was measured at baseline in a region of interest drawn around the medial tibia, and was adjusted for (i.e., expressed as a ratio to) uptake in a reference segment of the tibial shaft, which served as an internal standard. Each subject underwent a fluoroscopically standardized radiographic examination of the knees (semiflexed AP view) and a pain assessment with the WOMAC OA Index at baseline, 16 months, and 30 months. Results. Controlling for baseline joint space width and treatment group, multiple linear regression models showed that the adjusted 99mTc-MDP uptake at baseline was a significant predictor of joint space narrowing (JSN) in the index knee at 16 months (b = 0.180, p = 0.015) and 30 months (b = 0.221, p = 0.049). In the contralateral knee, uptake was only a marginally significant predictor of JSN at 30 months (b = 0.246, p = 0.083). Uptake in the upper and middle tertiles of the distribution predicted subjects who would exhibit JSN ≥ 0.50 mm within 16 months with 65% sensitivity (PPV 23%) and 36% specificity (NPV 77%). In contrast, a prediction rule based solely on the presence of Kellgren-Lawrence grade 3 OA severity and greater than median WOMAC Pain score identified progressors with 65% sensitivity (PPV 48%) and 79% specificity (NPV 88%). Conclusion. Although the level of adjusted 99mTc-MDP uptake was significantly associated with JSN in knees with established radiographic OA, baseline bone scintigraphy is inferior to the radiographic severity of OA and knee pain (alone or in combination) as a predictor of loss of articular cartilage in subjects with knee OA. (J Rheumatol 2005;32:1540-6) Key Indexing Terms:
OSTEOARTHRITIS
From the Department of Medicine, Department of Orthopaedic Surgery, and Department of Radiology, Indiana University School of Medicine (IUSM), Indianapolis, Indiana; Arthritis Research Center Foundation, Wichita, Kansas; University of Alabama at Birmingham, Birmingham, Alabama; University of Arizona, Tucson, Arizona; Northwestern University, Chicago, Illinois; University of Pittsburgh, Pittsburgh, Pennsylvania; and Procter & Gamble Pharmaceuticals Corp., Cincinnati, Ohio, USA. Supported in part by National Institutes of Health grants R01 AR43348, R01 AR43370, and P60 AR20582; and a grant from Procter & Gamble Pharmaceuticals. S.A. Mazzuca, PhD; B.P. Katz, PhD; K.A. Lane, MS; J.D. Bradley, MD; S.T. Hugenberg, MD, Department of Medicine, IUSM; K.D. Brandt, MD, Department of Medicine and Department of Orthopaedic Surgery, IUSM; D.S. Schauwecker, MD, Department of Radiology, IUSM; J.M. Meyer, PhD, Procter & Gamble Pharmaceuticals; F. Wolfe, MD, Arthritis Research Center Foundation; L.W. Moreland, MD; L.W. Heck, MD, University of Alabama at Birmingham; D.E. Yocum, MD, University of Arizona; L. Sharma, MD; T.J. Schnitzer, MD, Northwestern University; S. Manzi, MD; C.V. Oddis, MD, University of Pittsburgh. Address reprint requests to Dr. S.A. Mazzuca, Rheumatology Division, Department of Medicine, Indiana University School of Medicine, Long Hospital, Room 545, 1110 West Michigan Street, Indianapolis, IN 46202-5100. E-mail: smazzuca@iupui.edu Accepted for publication March 29, 2005. |