Myositis autoantibodies detected by line blot immunoassay: clinical associations and correlation with antibody signal intensity.

The aim of this study is to assess the relationship between myositis specific (MSA) and myositis associated (MAA) antibodies and diagnosis (including idiopathic inflammatory myopathies [IIM] and other systemic autoimmune diseases [SAID]), and to explore the impact of antibody signal intensity in diagnostic accuracy. We retrospectively reviewed all the serum samples obtained from patients tested for MSA/MAA by line immunoassay (LIA) between 01/01/2018 and 31/12/2020 in Ramón y Cajal University Hospital (Spain). Clinical true positive (CTP) MSAs and MAAs were defined as those patients with IIM or SAID with phenotypes expected of that MSA/MAA. Patients who did not have a phenotype compatible with that antibody were classified as clinical false positive (CFP). One hundred and thirty positive samples were analysed. Forty-six patients (33.38%) were classified as IIM, forty-two (32.3%) as SAID and forty-two (32.3%) as non-IIM/SAID. Among these 130 patients, 164 MSA/MAA were detected. Eighty-five (51.8%) positive MSA/MAA were classified as CTP, and seventy-nine (48.2%) as CFP. Strongly positive antibodies were more frequently CTP (35/47, 74.5%) than weak positives (54/68, 36.8%), (p ˂ 0.001). Antibodies classified as CTP had a higher signal intensity than CFP (36.77 AU vs 20.00 AU, CI95% 7.79-22.09, p ˂ 0.001). The probability of a CFP was associated to negative ANA, low ANA titer, and multiple positive MSA/MAA (p Ë‚ 0.001). In this study, we confirmed that CFP results using LIA are frequent, and are associated with low signal intensity MSA/MAA, negative ANA, lower titer ANA, and with multiple positive samples.

Evaluation of flare rate and reduction strategies for bDMARDs in juvenile idiopathic arthritis: real world data from a single-centre cohort.

This study aimed to determine the flare rate (FR) in a cohort of Juvenile Idiopathic Arthritis (JIA) patients with tapered or abruptly discontinued biologic disease-modifying anti-rheumatic drugs (bDMARDs) and to identify predictors of flare. This retrospective observational study included 191 bDMARD dose-reduction events in patients with JIA followed-up at a referral hospital during the period 2000-2019. FR was analysed according to reduction strategies. To identify predictors of flare, Kaplan-Meier and Cox-regression models were plotted at 6 months (6 m), 12 months (12 m) and 24 months (24 m) following tapering (TP) or withdrawal (WD). 165 episodes of TP and 71 episodes of WD were included; 45 episodes where treatment was withdrawn after TP were included in both strategies. FR after TP was 13.4% at 6 m and increased up to 26.6% at 12 m and 51.4% at 24 m. After WD, FR was higher, 52.1% of events had a flare at 6 m and 67.6% at 12 m. Previous TP did not increase time in remission after WD of bDMARDs in the Kaplan-Meier analysis. Factors associated with flares were identified after TP at 6 m: female sex, higher number of previous bDMARDs and longer time on bDMARD treatment were positively associated with flares. Polyarticular subtype and younger age at diagnosis were associated with flares at 12 and 24 m after TP. No factors were identified in multivariable analysis after WD. TP is a successful strategy to maintain remission with lower bDMARD doses. Previous TP of bDMARDs does not seem to increase time in remission after WD.

High rates of severe disease and death due to SARS-CoV-2 infection in rheumatic disease patients treated with rituximab: a descriptive study.

The objective of this study is to describe the characteristics and outcomes of rheumatic and musculoskeletal disease (RMD) patients who were treated with rituximab and had suspected or confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this descriptive study, RMD patients who were treated with rituximab in the last 12 months at the Rheumatology Department of our hospital were screened for SARS-CoV-2 infection via telephone interview and a comprehensive review of clinical health records (01/02/2020-26/05/2020). Those with probable or confirmed SARS-CoV-2 infection were included. In total, 76 patients were screened. Of these, 13 (17.1%) had suspected or confirmed SARS-CoV-2 infection. With regard to these 13 patients, the median age at coronavirus disease (COVID-19) diagnosis was 68 years (range 28-76 years) and 8 (61.5%) were female. Five patients had rheumatoid arthritis, three had systemic vasculitis, two had Sjögren syndrome, and two had systemic lupus erythematosus. Additionally, seven patients (53.8%) had pulmonary involvement secondary to RMD. Eight patients (61.5%) developed severe disease leading to hospitalization, and seven developed bilateral pneumonia and respiratory insufficiency. Of the eight hospitalized patients, five (62.5%) fulfilled the acute respiratory distress syndrome criteria and three developed a critical disease and died. Our cohort had a high rate of severe disease requiring hospitalization (61.5%), with bilateral pneumonia and hyperinflammation leading to a high mortality rate (23.1%). Treatment with rituximab should be considered a possible risk factor for unfavorable outcomes in COVID-19 patients with RMD. However, further study is required to confirm this association.