Department of Clinical Immunology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India.
Department of Biostatistics, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India.
Rheumatology (Oxford). 2024 Jan 4;63(1):111-118. doi: 10.1093/rheumatology/kead174.
To evaluate the relationship of thigh MRI (t-MRI) with manual muscle testing-8 (MMT-8), muscle enzymes and autoantibodies. To determine the causal and mediating factors resulting in poor recovery of MMT-8 in inflammatory myositis (IIM).
This was a single-centre retrospective study in IIM patients. t-MRI was semi-quantitatively scored for muscle oedema, fascial oedema, muscle atrophy and fatty infiltration. Spearman correlation of t-MRI scores was done with muscle enzymes at baseline, and MMT-8 at baseline and on follow-up. Causal mediation analysis was performed with age, sex, symptom duration, autoantibodies, diabetes and BMI as independent variables, follow-up MMT-8 as dependent and t-MRI scores as mediating variables.
Baseline evaluation was done on 59 and follow-up on 38 patients. Median follow-up of the cohort was 31 (10-57) months. Baseline MMT-8 negatively correlated with muscle oedema (r = -0755), fascial oedema (r = -0.443) and muscle atrophy (r = -0.343). Creatinine kinase (r = 0.422) and aspartate transaminase (r = 0.480) positively correlated with muscle oedema. Follow-up MMT-8 correlated negatively with baseline atrophy (r = -0.497) and fatty infiltration (r = -0.531). On follow-up, MMT-8 males had positive total effect (estimate (95%CI)) via atrophy [2.93 (0.44, 4.89)] and fatty infiltration [2.08 (0.54, 3.71)]. Antisynthetase antibody had a positive total effect via fatty infiltration [4.50 (0.37, 7.59)]. Age had a negative total effect via atrophy [-0.09 (0.19, -0.01)] and fatty infiltration [-0.07 (-0.15, -0.01)]. Disease duration had a negative total effect via fatty infiltration [-0.18 (-0.27, -0.02)].
Baseline fatty infiltration and muscle atrophy resulting from older age, female sex, longer disease duration and absent anti-synthetase antibodies, partly mediate muscle recovery in IIM.
评估大腿 MRI（t-MRI）与手动肌肉测试-8（MMT-8）、肌肉酶和自身抗体的关系。确定导致炎性肌病（IIM）中 MMT-8 恢复不佳的因果和中介因素。
这是一项单中心回顾性研究，纳入了 IIM 患者。对肌肉水肿、筋膜水肿、肌肉萎缩和脂肪浸润进行 t-MRI 半定量评分。对基线时 t-MRI 评分与肌肉酶、基线和随访时 MMT-8 进行 Spearman 相关性分析。以年龄、性别、症状持续时间、自身抗体、糖尿病和 BMI 为自变量，随访时 MMT-8 为因变量，t-MRI 评分作为中介变量进行因果中介分析。
对 59 名患者进行了基线评估，对 38 名患者进行了随访。该队列的中位随访时间为 31（10-57）个月。基线 MMT-8 与肌肉水肿（r=-0.755）、筋膜水肿（r=-0.443）和肌肉萎缩（r=-0.343）呈负相关。肌酸激酶（r=0.422）和天冬氨酸转氨酶（r=0.480）与肌肉水肿呈正相关。随访时，MMT-8 与基线时的萎缩（r=-0.497）和脂肪浸润（r=-0.531）呈负相关。在随访时，男性的 MMT-8 通过萎缩（估计值（95%CI））和脂肪浸润（估计值（95%CI））存在正的总效应[2.93（0.44，4.89）和 2.08（0.54，3.71）]。抗合成酶抗体通过脂肪浸润存在正的总效应[4.50（0.37，7.59）]。年龄通过萎缩（估计值（95%CI））和脂肪浸润（估计值（95%CI））存在负的总效应[-0.09（0.19，-0.01）和-0.07（-0.15，-0.01）]。疾病持续时间通过脂肪浸润存在负的总效应[-0.18（-0.27，-0.02）]。
基线时的脂肪浸润和肌肉萎缩是由年龄较大、女性、疾病持续时间较长和缺乏抗合成酶抗体引起的，这在一定程度上介导了 IIM 中的肌肉恢复。
