A close association of body cell mass loss with disease activity and disability in Chinese patients with rheumatoid arthritis

Abstract

Objectives: To investigate the association of body cell mass loss with disease activity and disability in rheumatoid arthritis patients.

Introduction: Rheumatoid cachexia, defined as the loss of body cell mass, is important but under-recognized and contributes to morbidity and mortality in patients with rheumatoid arthritis.

Methods: One hundred forty-nine rheumatoid arthritis patients and 53 healthy, non-rheumatoid arthritis control subjects underwent anthropometric measurements of body mass index and waist and hip circumferences. Bioelectrical impedance analysis was used to determine the subjects' body compositions, including fat mass, skeletal lean mass, and body cell mass. The disease activity of rheumatoid arthritis was assessed using C-reactive protein serum, the erythrocyte sedimentation rate and the 28-joint disease activity score, while disability was evaluated using a health assessment questionnaire.

Results: Rheumatoid arthritis patients had lower waist-to-hip ratio (0.86 ± 0.07 vs. 0.95 ± 0.06; p<0.001) and lower skeletal lean mass indexes (14.44 ± 1.52 vs. 15.18 ± 1.35; p = 0.002) than those in the healthy control group. Compared with rheumatoid arthritis patients with higher body cell masses, those with body cell masses lower than median had higher erythrocyte sedimentation rates (40.10 ± 27.33 vs. 25.09 ± 14.85; p<0.001), higher disease activity scores (5.36 ± 3.79 vs. 4.23 ± 1.21; p = 0.022) and greater disability as measured by health assessment questionnaire scores (1.26 ± 0.79 vs. 0.87 ± 0.79; p = 0.004).

Conclusions: The loss of body cell mass is associated with higher disease activity and greater disability in rheumatoid arthritis patients. Body composition determined by bioelectrical impedance analysis can provide valuable information for a rheumatologist to more rapidly recognize rheumatoid cachexia in rheumatoid arthritis patients.

Figures

Figure 1

Linear correlation between body cell mass (BCM) and body weight in (A) 149 RA patients (correlation coefficient = 0.62, p<0.001) and (B) 53 healthy control subjects, (correlation coefficient = 0.67, p<0.001) as determined by Pearson's correlation.

Figure 2

(A) Comparisons of body cell mass (BCM) values of RA patients with low, moderate and high levels of disease activity by analysis of variance. (B) Comparisons of BCM values of RA patients with and without disability by independent sample t-test. Values are presented as box-plot diagrams, with the box encompassing the range from the 25th percentile (lower bar) to the 75th percentile (upper bar). The horizontal line within the box indicates the median value, and the horizontal lines above and below the box represent the maximum and minimum values, respectively, for each group.