Cachexia in rheumatoid arthritis is associated with inflammatory activity, physical disability, and low bioavailable insulin-like growth factor.

I-L Engvall, A-C Elkan, B Tengstrand, T Cederholm, K Brismar, I Hafstrom

Department of Rheumatology, the Karolinska Institute, Karolinska University Hospital Huddinge, Stockholm, Sweden. inga-lill.engvall@karolinska.se

Scandinavian journal of rheumatology 2008 Sep-Oct

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To examine the impact of inflammation, insulin-like growth factor (IGF-1) and its regulating binding protein (IGFBP-1) on lean body mass (LBM) in patients with rheumatoid arthritis (RA). In 60 inpatients (50 women), inflammatory activity was measured by Disease Activity Score 28 (DAS28), C-reactive protein (CRP), and interleukin (IL)-6, and physical disability by the Health Assessment Questionnaire (HAQ). LBM was assessed by dual-energy X-ray absorptiometry (DXA) and fat free mass index (FFMI; kg/m(2)) and fat mass index (FMI; kg/m(2)) were calculated. Median age was 65 years and disease duration 13 years. Fifty per cent of the patients had FFMI below the 10th percentile of a reference population and 45% had FMI above the 90th percentile, corresponding to the condition known as rheumatoid cachexia (loss of muscle mass in the presence of stable or increased FM). DAS28, CRP, and IL-6 correlated negatively with LBM (p = 0.001, 0.001, and 0.018, respectively), as did HAQ (p = 0.001). Mean (confidence interval) IGF-1 was in the normal range, at 130 (116-143) microg/L. IGFBP-1 levels were elevated in patients (median 58 microg/L in women and 59 microg/L in men) compared with a normal population (33 microg/L in women and 24 microg/L in men). The ratio IGF-1/IGFBP-1, which reflects bioavailable IGF-1, was low (2.0 microg/L) and was positively correlated with LBM (p = 0.015). In multiple regression analysis, 42% of the LBM variance was explained by IGF-1/IGFBP-1, HAQ score, and DAS28. A large proportion of RA inpatients, mainly women, had rheumatoid cachexia. The muscle wasting was explained by inflammatory activity and physical disability as well as low bioavailable IGF-1.

Citation

I-L Engvall, A-C Elkan, B Tengstrand, T Cederholm, K Brismar, I Hafstrom. Cachexia in rheumatoid arthritis is associated with inflammatory activity, physical disability, and low bioavailable insulin-like growth factor. Scandinavian journal of rheumatology. 2008 Sep-Oct;37(5):321-8