Background The loss of muscle mass (MM) is a serious problem which may cause serious illness and premature death.
Several studies show that about two-thirds of Rheumatoid Arthritis (RA) patient’s have loss of MM, known as Rheumatoid Cachexia. Many factors were identified in the pathogenesis of this process: excessive production of cytokines TNF-α, low physical activity and reduction of the peripheral action of insulin. It is known that RA patients have higher rates of proteins degradation and it is thought that the TNF-α stimulates muscle catabolism, been described as a “sarcoactive” cytokine. The elevation of pro-inflammatory cytokines is also present in spondyloarthritis (Spa) so, like in RA, loss of MM may occur.
There are few studies about the association between loss of MM and Spa and the results are discrepant so, the effect of chronic inflammation and disease activity in body composition is still unknown.
Objectives Assess muscle mass index (MMI) in patients with Spa; verify if they have higher risk of sarcopenia and if the MMI is related with disease activity, functional impairment and duration of the illness.
Methods Case-control study, in a population of patients with Spa (axial or peripheral). The control group were users of a Family Health Unit.
Variables: sex; age; height; weight, duration of disease, pathological antecedents, chronic medication, MMI, disease activity (BASDAI and/or DAS28); BASFI and HAQ.
The MMI was determinated, from the value of MM, using Lee’s equation.
Results A sample of 60 patients was obtained; 52% were female. The average age was 45.5 years (± 13.4), and the average duration of the disease 10.9 years (± 11.6), 40% of patients met criteria for psoriatic arthritis (PsA).
According to the classification of the MMI, 62% of the patients had sarcopenia. There was a statistically significant difference between MMI of the Spa group and the control group (7.12 ± 0.99 vs. 7.8 ± 0.93; p < 0.05). The Odds ratio between cases and controls with and without sarcopenia was 2.1.
In the group of patients with ankylosing spondylitis no association was found between MMI and BASFI, BASDAI, or duration of the disease. However, in the subgroup of patients with PsA with axial involvement, a very strong negative correlation was found between MMI and the BASFI (rho =- 0.823; p < 0.05).
Sex, concomitant medication and pathological history doesn’t seem to influence the degree of sarcopenia.
Conclusions This study shows that the risk of sarcopenia in Spa patients is twice than in the control group. It hasn’t possible to identify the factors associated with that loss of MM, with the exception of a small group of patients with axial PsA, where a worse functional capacity was related with higher levels of sarcopenia.
The limitations of this study were: use of a non validated equation to calculate MM, small number of the sample and the bias of measurement.
Binymin K, Herrick A, Carlson G, Hopkins S. The effect of disease activity on body composition and resting energy expenditure in patients with rheumatoid arthritis. J Inflamm Res 2011; 4:61-66.
Beserra SR, Cavalcanti SV, Rocha Júnior LF et al. Caquexia reumatoide - como diagnosticar. RBM 2010: 67: 20-27.
Marcora S, Casanova F, Williams E, et al. Preliminary evidence for cachexia in patients with well-established ankylosing spondylitis. Rheumatology 2006; 45:1385-1388.
Disclosure of Interest None Declared
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