Objectives: This study aimed to examine whether creatine kinase (CK) elevation occurs with interleukin (IL)-6 inhibitors, as in Janus kinase (JAK) inhibitors, which are reported to increase CK levels in rheumatoid arthritis. Patients and methods: A multicenter database of JAK inhibitor and IL-6 inhibitor treatment was retrospectively searched between January 2016 to December 2022; 142 cases (117 females, 25 males, mean age: 63.8±13.0 years; range, 20 to 85 years), with 71 cases in each group, were extracted by propensity score matching using age, sex, body mass index, and CK at 0 weeks. The outlier rate was compared. Patients’ background characteristics related to elevated CK levels at 24 weeks were investigated by univariate and multivariate analyses. Results: Creatine kinase levels at 4 and 12 weeks were significantly higher with JAK inhibitors than with IL-6 inhibitors (four weeks, 72 vs. 87.5 IU/mL, p=0.016; 12 weeks, 71 vs. 95.5 IU/mL, p=0.028). The outlier rate (Grade 1) with JAK inhibitors increased significantly over time (0 weeks, 4.2%; four weeks, 18.1%; 12 weeks, 21.7%; 24 weeks, 18.3%; p=0.015), whereas that with IL-6 inhibitors increased slightly (0 weeks, 5.6%; four weeks, 9.2%; 12 weeks, 8.6%; 24 weeks, 8.5%; p=0.745), with a significant difference between the groups (p=0.035). No patients discontinued treatment due to myalgia or renal dysfunction. The factors significantly positively related to elevated CK levels at 24 weeks were male sex and creatinine. Those significantly negatively related were Steinbrocker stage and class, modified health assessment questionnaire scores, estimated glomerular filtration rate, and glucocorticoid dose. Conclusion: Mild CK elevations with JAK inhibitors are not a particular clinical problem. CK elevation might be specific to JAK inhibitors.

Sarcopenia is relatively common in rheumatoid arthritis (RA) patients. Thicknesses of the quadriceps muscle and fat are easily measured by ultrasound (US) and are known to be related to skeletal muscle mass and fat mass, respectively. Eighty-four patients enrolled in the prospective correlation research of sarcopenia, skeletal muscle, and disease activity in rheumatoid arthritis study (UMIN000023744) underwent US examinations of anterior thigh muscle thickness (MT) and fat thickness (FT). Muscle and body fat (BF) mass were also examined by a body composition analyzer. Whether MT and FT were related to sarcopenia and obesity was examined. MT was significantly lower in RA patients with sarcopenia than in those without (23.8 vs 28.2 mm, P = 0.001). MT was related to sarcopenia (men: r = 0.56, P = 0.02, women: r = 0.32, P = 0.01). The cut-off value of MT for sarcopenia was 24.7 mm in men and 19.7 mm in women on receiver operating characteristic curve analyses. FT was correlated with BF percentage (%BF; men: r = 0.66, P < 0.01, women: r = 0.62, P < 0.001), which was estimated by 2.04xFT+8.53 in men and 1.2xFT+17.42 in women by a simple linear regression model. This means that FT ≥ 8.1 mm in men and FT ≥ 14.6 mm in women indicated obesity. US examination of the anterior thigh was useful to detect sarcopenia and obesity in RA patients.

Yingtian Tang, Yutaro Yamada, Yoyo Zhang, Ilker Yildirim. Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing. 2023.

Osteosarcopenia is defined as osteoporosis with sarcopenia. The impacts of osteosarcopenia on falls and fractures in rheumatoid arthritis (RA) patients were investigated using 4 years of data from a longitudinal study (CHIKARA study). The patients were divided into 4 groups by their baseline status: no sarcopenia and no osteoporosis (SP-OP-); only sarcopenia (SP + OP-); only osteoporosis (SP-OP+); and both sarcopenia and osteoporosis (SP + OP+). Survival rates and Cox hazard ratios were analyzed using falls and fractures as endpoints, adjusted by age, sex, and body mass index. A total of 100 RA patients (SP-OP-: 44%, SP + OP-: 17%, SP-OP+: 28%, and SP + OP+: 11%) were enrolled; 37 patients had falls, and 19 patients had fractures. The fall-free and fracture-free survival rates were significantly lower in SP + OP+ (36.4%, 54.5%) than in SP-OP- (75.0%, 86.4%). The hazard ratio of falls was significantly increased in SP + OP+, by 3.32-fold (95%CI: 1.01–10.9), whereas in SP + OP- and SP-OP+, there were no differences compared to SP-OP-. The survival rates with the endpoints of falls and fractures in RA patients with osteosarcopenia were lower during 4-year follow-up. The risk of falls increased with the synergistic effect of osteoporosis and sarcopenia.