SARCOPENIA REVERSAL IN ANKYLOSING SPONDYLITIS (AS) UNDER ANTI-TNF THERAPY: A 24-MONTH LONGITUDINAL ANALYSIS

Abstract

Introduction: Sarcopenia is a syndrome characterized by progressive loss of skeletal muscle mass, which results in decreased muscle strength and impairment of physical and functional capacity. There are no data regarding this disorder in AS patients and the possible beneficial effect of anti-TNF therapy in this complication. Aim: To determine the frequency of sarcopenia in AS patients and the effect of anti-TNF treatment in this condition. Materials and Methods: Thirty active AS patients were assessed at baseline (BL), 6(6M), 12(12M) and 24 months(24M) after anti-TNF therapy. Patients were evaluated for clinical parameters and inflammatory markers. Physical activity remained stable during the study. Body weight and Body Mass Index(BMI) were also measured. Fat mass(FM), total lean mass(LM) and appendicular lean mass(ASM=sum of arms and legs) were analyzed by dual-energy X-ray absorptiometry(DXA). Sarcopenia was defined when the relative skeletal muscle mass index(RSMI=ASM/height2) was less than 5.45 kg/m2 for women and 7.26 kg/m2 for men(Baumgartner´s criteria). Results: Sarcopenia was found in 16.6% of AS patients. There was a significant decrease in the frequency of sarcopenia with a complete reversion at 24 months (BL:16.6% vs. 6M:13.3% vs. 12M:6.6% vs. 24M:0%, p<0.001). This finding was paralleled by an increase of body weight (BL:72.65 kg vs. 6M:73.87kg vs. 12M:74.65kg vs. 24M:75.01kg, p=0.007), BMI (p=0.038) and total lean mass (BL:52.56kg vs. 6M:53.19kg vs. 12M: 54.08kg vs. 24M:54.01kg, p=<0.001), particularly in the first 12 months of therapy (BL vs. 12 months, p<0.05). No difference was observed in fat mass (p>0.05) and percentage of fat mass (BL:24.14% vs. 6M:24.27% vs. 12M:54.08% vs. 24M:24.86%, p=0.146). BASDAI (p<0.001), BASFI (p=0.001) and AsQoL (p<0.001) improved during study period, with a significant reduction in ESR (p<0.001) and CRP levels (p<0.001) after TNF therapy. Conclusion: The novel demonstration of anti-TNF induced recovery in sarcopenia reinforces its beneficial effect in muscle mass and functional capacity in AS patients, most likely associated with a reduction of inflammation.