Maria Isabel Cardoso Dos Passos Carvalho1, Samuel Katsuyuki Shinjo2,3. 1. Division of Rheumatology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil. 2. Division of Rheumatology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil. samuel.shinjo@gmail.com. 3. Disciplina de Reumatologia, Faculdade de Medicina, Universidade de Sao Paulo, Av. Dr. Arnaldo, 455, 3° andar, sala 3150 - Cerqueira César, Sao Paulo, CEP: 01246-903, Brazil. samuel.shinjo@gmail.com.
Abstract
BACKGROUND: To analyze the frequency and clinical relevance of anti-Mi-2 autoantibody in a representative sample of patients with dermatomyositis. METHODS: This longitudinal inception cohort study, from 2001 to 2017, included 87 definite adult dermatomyositis. Anti-Mi-2 analysis was performed using a commercial kit. RESULTS: Seventeen patients (19.5%) had anti-Mi-2 and 70 (80.5%) did not have this autoantibody. The following parameters were equally distributed between the patients with versus without anti-Mi-2: mean age at the disease diagnosis onset, median follow-up time, constitutional symptoms (baseline), cutaneous cumulative lesions, dysphagia, joint and pulmonary involvement. There was also no difference between the groups in relation to follow-up time, disease relapsing, treatment, disease status, deaths and occurrence of neoplasia. In contrast, patients with anti-Mi2 antibodies had higher frequency of elevated serum levels of muscle enzymes at disease onset (median: creatine phosphokinase 6240 [3800-9148] U/L and aldolase 60.0 [35.0-138.0] U/L), lower frequency of pulmonary involvement at disease onset (5.9%), less current glucocorticoid dose (median: 0 [0-10] mg/day), and higher frequency of disease remission during follow-up (58.8%) in comparison with patients without anti-Mi-2 autoantibody (484 [115-4880] and 12.1 [6.3-70.0] U/L, 40.0%, 0 [0-10] mg/day, 27.1%, respectively). CONCLUSION: The anti-Mi-2 autoantibody was found in one fifth of patients with dermatomyositis. This autoantibody was associated with a lower occurrence of pulmonary involvement, a higher frequency of disease in remission, and elevated levels of muscle enzymes. There was also no correlation regarding the frequency of disease relapsing or neoplasia development.
BACKGROUND: To analyze the frequency and clinical relevance of anti-Mi-2 autoantibody in a representative sample of patients with dermatomyositis. METHODS: This longitudinal inception cohort study, from 2001 to 2017, included 87 definite adult dermatomyositis. Anti-Mi-2 analysis was performed using a commercial kit. RESULTS: Seventeen patients (19.5%) had anti-Mi-2 and 70 (80.5%) did not have this autoantibody. The following parameters were equally distributed between the patients with versus without anti-Mi-2: mean age at the disease diagnosis onset, median follow-up time, constitutional symptoms (baseline), cutaneous cumulative lesions, dysphagia, joint and pulmonary involvement. There was also no difference between the groups in relation to follow-up time, disease relapsing, treatment, disease status, deaths and occurrence of neoplasia. In contrast, patients with anti-Mi2 antibodies had higher frequency of elevated serum levels of muscle enzymes at disease onset (median: creatine phosphokinase 6240 [3800-9148] U/L and aldolase 60.0 [35.0-138.0] U/L), lower frequency of pulmonary involvement at disease onset (5.9%), less current glucocorticoid dose (median: 0 [0-10] mg/day), and higher frequency of disease remission during follow-up (58.8%) in comparison with patients without anti-Mi-2 autoantibody (484 [115-4880] and 12.1 [6.3-70.0] U/L, 40.0%, 0 [0-10] mg/day, 27.1%, respectively). CONCLUSION: The anti-Mi-2 autoantibody was found in one fifth of patients with dermatomyositis. This autoantibody was associated with a lower occurrence of pulmonary involvement, a higher frequency of disease in remission, and elevated levels of muscle enzymes. There was also no correlation regarding the frequency of disease relapsing or neoplasia development.