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IgG4-related disease (IgG4-RD) can cause fibroinflammatory lesions in nearly any organ. Correlation among clinical, serological, radiological and pathological data is required for diagnosis. This work was undertaken to develop and validate an international set of classification criteria for IgG4-RD. An international multispecialty group of 86 physicians was assembled by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR). Investigators used consensus exercises; existing literature; derivation and validation cohorts of 1879 subjects (1086 cases, 793 mimickers); and multicriterion decision analysis to identify, weight and test potential classification criteria. Two independent validation cohorts were included. A three-step classification process was developed. First, it must be demonstrated that a potential IgG4-RD case has involvement of at least one of 11 possible organs in a manner consistent with IgG4-RD. Second, exclusion criteria consisting of a total of 32 clinical, serological, radiological and pathological items must be applied; the presence of any of these criteria eliminates the patient from IgG4-RD classification. Third, eight weighted inclusion criteria domains, addressing clinical findings, serological results, radiological assessments and pathological interpretations, are applied. In the first validation cohort, a threshold of 20 points had a specificity of 99.2% (95% CI 97.2% to 99.8%) and a sensitivity of 85.5% (95% CI 81.9% to 88.5%). In the second, the specificity was 97.8% (95% CI 93.7% to 99.2%) and the sensitivity was 82.0% (95% CI 77.0% to 86.1%). The criteria were shown to have robust test characteristics over a wide range of thresholds. ACR/EULAR classification criteria for IgG4-RD have been developed and validated in a large cohort of patients. These criteria demonstrate excellent test performance and should contribute substantially to future clinical, epidemiological and basic science investigations.

Objective IgG4-related disease (IgG4-RD) can cause fibroinflammatory lesions in nearly any organ. Correlation among clinical, serologic, radiologic, and pathologic data is required for diagnosis. This work was undertaken to develop and validate an international set of classification criteria for IgG4-RD. Methods An international multispecialty group of 86 physicians was assembled by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR). Investigators used consensus exercises, existing literature, derivation and validation cohorts of 1,879 subjects (1,086 cases, 793 mimickers), and multicriterion decision analysis to identify, weight, and test potential classification criteria. Two independent validation cohorts were included. Results A 3-step classification process was developed. First, it must be demonstrated that a potential IgG4-RD case has involvement of at least 1 of 11 possible organs in a manner consistent with IgG4-RD. Second, exclusion criteria consisting of a total of 32 clinical, serologic, radiologic, and pathologic items must be applied; the presence of any of these criteria eliminates the patient from IgG4-RD classification. Third, 8 weighted inclusion criteria domains, addressing clinical findings, serologic results, radiology assessments, and pathology interpretations, are applied. In the first validation cohort, a threshold of 20 points had a specificity of 99.2% (95% confidence interval [95% CI] 97.2-99.8%) and a sensitivity of 85.5% (95% CI 81.9-88.5%). In the second, the specificity was 97.8% (95% CI 93.7-99.2%) and the sensitivity was 82.0% (95% CI 77.0-86.1%). The criteria were shown to have robust test characteristics over a wide range of thresholds. Conclusion ACR/EULAR classification criteria for IgG4-RD have been developed and validated in a large cohort of patients. These criteria demonstrate excellent test performance and should contribute substantially to future clinical, epidemiologic, and basic science investigations.

Background: Glucocorticoids (GCs) plus rituximab (RTX) represent the first-line treatment of nonviral mixed cryoglobulinemia vasculitis (CryoVas). However, data on therapeutic management and outcome of patients refractory to RTX are lacking. Methods: We conducted a European collaborative retrospective multicenter study of patients with nonviral mixed CryoVas refractory to RTX and performed a literature review. Results: Twenty-six original cases and 7 additional patients from the literature were included. All patients but one had type 2 cryoglobulinemia, and causes were autoimmune disease (51%), malignant hemopathy (12%) or essential CryoVas (42%). CryoVas was primary refractory to RTX in 42%, while 58% had an initial response to RTX before immune escape. After RTX failure, patients received a median of 1 (IQR, 1–3) line of treatment, representing 65 treatment periods during follow-up. Main treatments used were GCs in 92%, alkylating agents in 43%, RTX in combination with other treatments in 46%, and belimumab in 17%. Combination of anti-CD20 plus belimumab, alkylating agents alone and anti-CD20 plus alkylating agents provided the highest rates of clinical response in 100% 82% and 73%, respectively, but showed poor immunological response, in 50%, 30% and 38%, respectively. Rates of severe infection were 57%, 9% and 0% in patients receiving anti-CD20 plus belimumab, alkylating agents alone and anti-CD20 plus alkylating agents, respectively. Conclusion: In patients with nonviral mixed CryoVas refractory to RTX, anti-CD20 plus belimumab, and alkylating agents associated or not with anti-CD20, provide the highest rates of clinical response. However, anti-CD20 plus belimumab was frequently associated with severe infections.

OBJECTIVE:IgG4-related disease (IgG4-RD) can cause fibroinflammatory lesions in nearly any organ, leading to organ dysfunction and failure. The IgG4-RD Responder Index (RI) was developed to help investigators assess the efficacy of treatment in a structured manner. The aim of this study was to validate the RI in a multinational investigation. METHODS:The RI guides investigators through assessments of disease activity and damage in 25 domains, incorporating higher weights for disease manifestations that require urgent treatment or that worsen despite treatment. After a training exercise, investigators reviewed 12 written IgG4-RD vignettes based on real patients. Investigators calculated both an RI score as well as a physician's global assessment (PhGA) score for each vignette. In a longitudinal assessment, 3 investigators used the RI in 15 patients with newly active disease who were followed up over serial visits after treatment. We assessed interrater and intrarater reliability, precision, validity, and responsiveness. RESULTS:The 26 physician investigators included representatives from 6 specialties and 9 countries. The interrater and intrarater reliability of the RI was strong (0.89 and 0.69, respectively). Correlations (construct validity) between the RI and PhGA were high (Spearman's r = 0.9, P < 0.0001). The RI was sensitive to change (discriminant validity). Following treatment, there was significant improvement in the RI score (mean change 10.5 [95% confidence interval (95% CI) 5.4-12], P < 0.001), which correlated with the change in the PhGA. Urgent disease and damage were captured effectively. DISCUSSION:In this international, multispecialty study, we observed that the RI is a valid and reliable disease activity assessment tool that can be used to measure response to therapy.