Thigh Fat Area, Muscle Density Linked to RA Indicators

Fat area and muscle density, but not muscle area, associated with disability, physical performance

FRIDAY, March 23 (HealthDay News) -- Thigh fat area and muscle density, but not muscle area, are indicators of disability and physical performance in patients with rheumatoid arthritis (RA), according to a study published online March 5 in Arthritis & Rheumatism.

Henry R. Kramer, M.D., from Johns Hopkins University in Baltimore, Md., and colleagues used quantitative computed tomography (CT) to measure thigh muscle density, thigh muscle area, and thigh fat area in 152 patients with RA.

The researchers found that lower muscle density was significantly associated with a wide range of factors, including older age, greater length of sedentary activity, and longer RA duration. Disease characteristics could account for 77 percent of the explainable muscle density variability. There was also a significant and independent association of higher fat area and lower muscle density, but not thigh muscle area, with measures of disability and physical performance, as assessed by Health Assessment Questionnaire scores, Short Form-36 physical scores, Short Physical Performance Battery scores, and the Valued Life Activities scale.

"Thigh CT-derived measures of body composition, particularly fat area and muscle density, were strongly associated with disability and physical performance in RA patients, with RA disease features as potential determinants," Kramer and colleagues conclude. "Efforts to reduce fat and improve muscle quality may reduce disability in this population with impaired physical functioning."

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