The role of muscle biopsy score in assessing disease activity in adult patients with idiopathic inflammatory myopathies / 中华风湿病学杂志

ABSTRACT

Objective To investigate the role of muscle biopsy score in the assessment of the disease activity of idiopathic inflammatory myopathy (IIM) in Chinese adult patients.Methods Total 423 adult IIM patients charged in thedepartment of rheumatology of China-Japan Friendship Hospital from December 2008 to June 2017 were included in this study.The score of disease activity was assessed using International Myositis Assessment and Clinical Studies Group (IMACS) Core Set Measures of IIM.Muscle tissue specimens of IIM patients wasimmunohistochemically stained formajorhistocompatibilitycomplex (MHC)-Ⅰ,CD3 and CD20 molecules.The muscle biopsy score of each specimens was measured separately by four parts of muscle tissue according to muscle fiber,inflammation infiltrating,blood vessel and connective tissue.The correlation between disease activity and muscle biopsy score of IIM was analysed.Statistical analyses were performed using Statistical Product and Service Solutions (SPSS) software.Nonparametric Mann-Wittney U test,Wilcoxon rank sum test and Fisher's exact test were used for between-group comparisons.Nonparametric Spearman's rank correlation was used for correlation analysis.P＜0.05 was considered statistically significant differences.Results The degree of muscle biopsy score was associated with the overall disease activity (r=0.228,P＜0.05),muscle visual analog scale (VAS) (r=0.407,P＜0.05) and the serum levels of creatine kinase (CK) (r=0.466,P＜0.05) of IIM patients,respectively.Among 127 initial patients including 92 dermatoimyositis (DM) and 35polymyositis (PM),the muscle VAS of DM patients were positivelycorrelated to thetotal muscle biopsy score,the score of muscle fiber and inflammation infiltrating (r=0.30,0.312 and 0.241,P＜0.05),respectively.While,the high disease activity of PM patients was related to the increased muscle fiber score (r=0.478,P＜0.05).Conclusion Measurement of muscle biopsy score can be used as an effective tool to evaluate the disease activity of IIM.