Clinical characteristics of idiopathic inflammatory myopathy patients with positive anti-melanoma differentiation-associated gene 5 antibody / 中华风湿病学杂志

ABSTRACT

Objective:To investigate the clinical characteristics and prognosis of idiopathic inflammatory myopathy (IIM) patients with positive anti-melanoma differentiation-associated gene 5 (MDA5) antibody.Methods:A total of 194 hospitalized IIM patients who were tested for myositis-specific autoantibodies (MSAs) in the Departments of Rheumatology and Immunology of Tianjin Medical University General Hospital from January 2015 to September 2020 were collected, including 29 cases with positive anti-MDA5 antibody and 165 cases with negative anti-MDA5 antibody. Their clinical data were analyzed retrospectively. T test was used for measurement data with normal distribution. Measurement data with non-normal distribution were tested by Mann-Whitney U rank sum test. χ2 test was used for counting data. Risk factors were analyzed by binary Logistic regression, survival analysis by Kaplan-Meier method and Cox regression analysis. Results:IIM patients with positive anti-MDA5 antibody had a high incidence of dermatomyositis specific skin rash, and the skin rash was the most common presenting symptom. In the positive anti-MDA5 antibody group, muscle symptoms were mild; and the patients were prone to have fever, arthritis, oral ulcer and weight loss. All patients were complicated with interstitial lung disease (ILD). In patients with negative anti-MDA5 antibody, white blood cell (WBC) count [7.59(5.61, 9.89)×10 9/L vs 4.07(3.17, 5.50×10 9/L, Z=-5.05, P<0.001], platelet (PLT) [249.00 (200.00, 302.00)×10 9/L vs 205.00 (178.00, 244.00)×10 9/L, Z=-2.59, P=0.010], lymphocyte (LY) [1.34(0.85, 1.94)×10 9/L vs 0.64(0.40, 0.83)×10 9/L, Z=-5.78, P<0.001), serum creatine kinase (CK) [558.00 (72.00, 2 959.00) U/L vs 64.00 (35.00, 149.50) U/L, Z=-3.97, P<0.001], creatine kinase isoenzymes (CK-MB) [38.00 (17.00, 127.00) U/L vs 16.00 (14.00, 25.00) U/L, Z=-3.84, P<0.001], myoglobin (MYO) [243.65 (60.50, 829.83) ng/ml vs 34.55(21.00, 104.23) ng/ml, Z=-3.98, P<0.001], troponin T (TnT) [0.09(0.03, 0.44) ng/ml vs 0.02(0.01, 0.04) ng/ml, Z=-4.17, P<0.001], albumin (ALB) [34.00(30.00, 38.00) g/L vs 31.00 (26.50, 36.00) g/L, Z=-2.68, P=0.007], cluster of differentiation 4 (CD4) + T cells [498.00(276.00, 752.00) cells/μl vs 259.50 (179.00, 498.25) cells/μl, Z=-2.79, P=0.005], partial pressure of carbon dioxide (PaCO 2) [39.00(36.13, 42.00) mmHg vs 35.35 (31.30, 38.88) mmHg, Z=-3.75, P<0.001], partial pressure of oxygen (PaO 2) [82.00(71.90, 90.20) mmHg vs 73.25(64.30, 84.05) mmHg, Z=-2.08, P=0.037], arterial oxygen saturation (SaO 2) [96.50% (95.05%, 97.30)% vs 95.80%(93.70%, 96.55%), Z=-2.11, P=0.035], diffusion capacity for carbon monoxide of the Lung (DLco) [(63±21) % vs (52±14)%, t=0.96, P=0.006] were significantly reduced, while UTP [260.50 (172.25, 401.25) g vs 331.00 (252.75, 666.25) g, Z=-2.18, P=0.029], alanine aminotransferase (ALT) [40.00 (21.00, 83.00) U/L vs 56.00(40.00, 107.50), Z=-2.27, P=0.023], glutamyltranspeptidas (GGT) [22.50(15.00, 42.00) U/L vs 57.00 (38.00, 101.50) U/L, Z=-4.98, P<0.001], D-Dimer [850.00 (485.00, 1 799.50) ng/ml vs 1 346.00 (896.50, 2 527.00) ng/ml, Z=-2.55, P=0.011], immunoglobulin (Ig)E [60.00 (25.60, 147.50) U/ml vs 173.00(68.25, 471.50) U/ml, Z=-3.06, P=0.002], C4[20.25(16.68, 25.03) mg/L vs 23.60(20.20, 28.35) mg/L, Z=-2.38, P=0.017], Fer [228.01 (115.40, 513.36) ng/ml vs 1 636.39 (851.80, 3 888.82) ng/ml, Z=-6.01, P<0.001], krebsvondenlungen-6 (KL-6) [365.00 (180.25, 1 018.75) U/ml vs 788.00 (406.00, 1 364.00) U/ml, Z=-2.10, P=0.035] were higher when compared to patients with positive anti-MDA5 antibody. In the anti-MDA5 antibody positive group, patients had high mortality rate [8.5%(14/165) vs 34.5%(10/29), χ2=13.07, P<0.001], and the use of intravenous immunoglobulin [32.7%(54/165) vs 65.5%(19/29), χ2=11.30, P=0.001] and steroid pulse therapy [4.8%(86/165) vs 27.6%(8/29), χ2=13.98, P<0.001] were more frequent. Patients in the positive anti-MDA5 antibody group were classified into two sub groups based on lung features the rapidly progressive interstitial lung disease (RP-ILD) group (48.28%, 14/29) and the chronic interstitial lung disease (C-ILD) group (51.72%, 15/29). RP-ILD patients had significantly elder disease onset age, higher C-reaction protein (CRP), Fer, IgE levels and the positive rate of anti-Ro52 antibody, while ALT was lower. The difference was statistically significant. Regression analysis suggested that older onset age [ HR (95% CI)=1.154 (1.069, 1.246), P<0.001], male [ HR(95% CI)=6.383(1.038, 39.242), P=0.045], positive anti-MDA5 antibody [ HR(95% CI)=17.180 (2.900, 101.766), P=0.002], LY decrease [ HR (95% CI)=0.083 (0.008, 0.817), P=0.033], high serum Fer level [ HR (95% CI)=1.001(1.000, 1.001), P=0.016], increased D-Dimer [ HR(95% CI)=1.000(1.000, 1.001), P=0.004] and compicated with carcinoma [ HR (95% CI)=11.849 (1.978, 70.970), P=0.007] were independent risk factors for death in IIM patients. Binary logistic regression analysis suggested that late onset age [ OR(95% CI)=1.090 (1.005, 1.183), P=0.038], high Fer level [ OR (95% CI)=1.001 (1.000, 1.001), P=0.022] and decreased ALB [ OR (95% CI)=0.818 (0.696, 0.963), P=0.016] might be risk factors for RP-ILD in patients with positive anti-MDA5 antibody. Conclusion:In patients with positive anti-MDA5 antibody group, typical skin damage, mild muscle symptoms, high proportion of ILD and poor prognosis are chardcteristic when compared to patients without this autoantibody. It is necessary to monitor the disease activity closely and explore the treatment strategy.