BACKGROUND: Antineutrophil cytoplasmic antibody-associated vasculitides (AAV) is a group of systemic necrotizing small vessel autoimmune diseases, with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) being the two most common. The co-existence of AAV with different immune-mediated diseases (autoimmune disesases - AID) might affect the clinical presentation of the primary disease. The purpose of the study was to assess the co-existence of AAV with AID and to investigate whether it affects the characteristics and the course of AAV.
METHODS: A retrospective single-center study was performed to identify patients with a diagnosis of MPA or GPA and concomitant AID, and to investigate their clinical features and characteristics. The group consisted of consecutive unselected AAV patients treated at a large university-based hospital, since 1988 with follow-up until 2022.
RESULTS: Among 284 patients diagnosed either with GPA (232) or MPA (52), 40 (14,1%) had co-existing AIDs. The most frequent were: Hashimoto thyroiditis (16 cases), rheumatoid arthritis (8 cases), followed by psoriasis (6 cases), pernicious anemia (3 cases), and alopecia (3 cases). Patients with autoimmune comorbidities had a significantly longer time between the onset of symptoms and the diagnosis (26 vs. 11 months, p < 0.001). Laryngeal involvement (20.0% vs. 9.0%, p = 0,05), peripheral nervous system disorders (35.0% vs. 13.9%, p < 0.001), and neoplasms (20.0% vs. 8.6%, p = 0,044) were more common in patients with AID comorbidities, compared to subjects without AID. In contrast, renal involvement (45.0% vs. 70.9%, p = 0.001) and nodular lung lesions (27.5% vs. 47.5%, p = 0.044) were significantly less frequent in patients with co-morbidities. Following EUVAS criteria, patients with autoimmune co-morbidities had a generalized form of the disease without organ involvement (52.5% vs. 27.2%, p = 0.007), while the others had a higher percentage of generalized form with organ involvement (38.3% vs. 20.0%, p = 0.007).
CONCLUSIONS: The coexistence of AAV with different autoimmune diseases is not common, but it might affect the clinical course of the disease. Polyautoimmunity prolonged the time to diagnosis, but the AAV course seemed to be milder. Particular attention should be paid to the increased risk of cancer in these patients. It also seems reasonable that AAV patients should receive a serological screening to exclude the development of overlapping diseases.

OBJECTIVE: To investigate the epidemiological features of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) in South Korea.
METHODS: We identified the index cases of GPA and MPA using the 2010-2018 Korean National Health Insurance Service database and the Rare Intractable Disease registry for the entire Korean population. Each disease\'s incidence and prevalence rates and trends over time were analysed. To assess the impact of disease on morbidity and mortality, a comparator group comprising the general population was established using nearest-neighbour matching by age, sex, income, and comorbidity index, at a 5:1 ratio. Morbidity outcomes included the initiation of renal replacement therapy and admission to the intensive care unit.
RESULTS: We identified 546 and 795 patients with GPA and MPA, respectively. The incidence rates of both diseases increased with age, with peak incidence rates observed among patients aged ≥70 years. The incidence of MPA increased continuously over time, whereas that of GPA showed no significant changes. During the observation period, 132 (28.7%) and 277 (41.1%) patients in the GPA and MPA groups, respectively, died, which were significantly higher than that in the general population (standardised mortality ratio: 3.53 and 5.58, respectively) and comparator group (hazard ratio: 4.02 and 5.64, respectively). Higher mortality and morbidity rates were observed among patients with MPA than among those with GPA.
CONCLUSIONS: In South Korea, the incidence of MPA has increased over time. Although both GPA and MPA had high rates of mortality and morbidity, MPA has a poorer prognosis than GPA.

BACKGROUND: Several studies have demonstrated that mycophenolate mofetil (MMF) may be an excellent alternative to cyclophosphamide (CYC) or rituximab for the induction of remission in non-life-threatening anti-neutrophil cytoplasmic antibodies associated vasculitis because of its strong immunosuppressive potency and low toxicity profile. Enteric-coated mycophenolate sodium (EC-MPS) was introduced to reduce gastrointestinal adverse reactions of MMF. This study will evaluate the efficacy and safety of EC-MPS combined with glucocorticoid in patients with active and non-life-threatening microscopic polyangiitis (MPA).
METHODS: This study is a multicentre, open-label, randomised controlled, non-inferiority trial. A total of 110 patients with active and non-life-threatening MPA from 11 hospitals in Shanxi Province of China will be recruited and randomised in a 1:1 ratio to receive either EC-MPS or CYC. All patients will receive the same glucocorticoid plan. We will compare oral EC-MPS (720-1440 mg/day) with intravenous pulsed CYC (7.5-15 mg/kg) administered for 3-6 months. All patients will be switched from their assigned treatment (EC-MPS or CYC) to oral azathioprine (2 mg/kg/day) after remission has been achieved, between 3 and 6 months. Azathioprine will be continued until the study ends at 18 months. The primary end point of efficacy is the remission rate at 6 months. Follow-up will continue for 18 months in order to detect an influence of induction regimen on subsequent relapse rates.
BACKGROUND: This study has received approval from the Ethics Committee of the Second Hospital of Shanxi Medical University (2022YX-026). All participants are required to provide written informed consent and no study-related procedures will be performed until consent is obtained. The results of this trial will be published in peer-reviewed journals and presented at conferences.
BACKGROUND: ChiCTR2200063823.

To establish refined risk prediction models for mortality in patients with microscopic polyangiitis (MPA) by using comprehensive clinical characteristics.
Data from the multicentre Japanese registry of patients with vasculitis (REVEAL cohort) were used in our analysis. In total, 194 patients with newly diagnosed MPA were included, and baseline demographic, clinical, laboratory, and treatment details were collected. Univariate and multivariate analyses were conducted to identify the significant risk factors predictive of mortality.
Over a median follow-up of 202.5 (84-352) weeks, 60 (30.9%) of 194 patients died. The causes of death included MPA-related vasculitis (18.3%), infection (50.0%), and others (31.7%). Deceased patients were older (median age 76.2 years) than survivors (72.3 years) (P < 0.0001). The death group had shorter observation periods (median 128.5 [35.3-248] weeks) than the survivor group (229 [112-392] weeks). Compared to survivors, the death group exhibited a higher smoking index, lower serum albumin levels, higher serum C-reactive protein levels, higher Birmingham Vasculitis Activity Score (BVAS), higher Five-Factor Score, and a more severe European Vasculitis Study Group (EUVAS) categorization system. Multivariate analysis revealed that higher BVAS and severe EUVAS independently predicted mortality. Kaplan-Meier survival curves demonstrated lower survival rates for BVAS ≥20 and severe EUVAS, and a risk prediction model (RPM) based on these stratified patients into low, moderate, and high-risk mortality groups.
The developed RPM is promising to predict mortality in patients with MPA and provides clinicians with a valuable tool for risk assessment and informed clinical decision-making.

OBJECTIVE: This study aimed to investigate the clinical outcomes of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) under rituximab induction and reinduction therapy in Taiwan.
METHODS: We performed a retrospective study in patients with GPA or MPA receiving rituximab therapy from August 2008 to July 2020 in seven medical centers in Taiwan. The clinical characteristics and outcomes of these patients were analyzed.
RESULTS: In total, 53 patients (18 with GPA and 35 with MPA) were included. Kidney involvement (82.9% vs. 22.2%, p < .001) and initial creatinine (3.25 ± 2.37 vs. 1.07 ± 0.82, p < .001) were significantly higher in MPA. Within 24 weeks after the first course of rituximab, there were seven deaths (five due to infection and two due to active disease) in patients with MPA (7/35, 20%) compared to 0 in patients with GPA. Of 33 patients receiving rituximab for kidney involvement, 23 survived and were free from renal replacement therapy at 24 weeks. Their chronic kidney disease (CKD) stages improved in 2 but progressed in 7, while 24 had stable CKD stages. Death or end-stage renal disease (ESRD) was associated with infection and higher initial creatinine. Reinduction therapy for relapse was required in 18 (39.1%) of 46 survivors, which was associated with anti-proteinase 3 (PR3) positive (odds ratio 3.667, p = .049) and younger age with a cutoff of 49.4 (AUC = 0.679, p = .030, sensitivity = 66.67%, specificity = 75%).
CONCLUSIONS: Significant mortality occurred after rituximab induction, especially in patients with MPA. In survivors, age younger than 50 and anti-PR3 positive were associated with the risk of relapse requiring reinduction.

UNASSIGNED: Previous studies have identified the predictors of severe infections in ANCA-associated vasculitis. However, lymphopenia has not been fully evaluated as a predictor of subsequent severe infections in patients with microscopic polyangiitis (MPA). The aim of this study was to assess the association between lymphopenia and severe infections requiring hospitalization after receiving immunosuppressive therapy for MPA.
UNASSIGNED: This single-centre retrospective cohort study included 130 consecutive patients with newly diagnosed MPA from Aichi Medical University Hospital, Japan, who received immunosuppressive therapy between March 2004 and December 2020. The relationship between lymphopenia and subsequent severe infections was assessed using time-dependent multivariate Cox proportional hazard models adjusted for clinically relevant factors.
UNASSIGNED: During the follow-up period (median: 38 months; interquartile range: 15-63 months), 56 severe infectious episodes occurred in 51 patients (39.2%). Time-dependent multivariate Cox proportional hazard analyses identified older age [adjusted hazard ratio (HR) = 1.74 per 10 years, 95% CI: 1.13, 2.67], methylprednisolone pulse therapy (adjusted HR = 2.04, 95% CI: 1.03, 4.02), moderate lymphopenia (vs normal, adjusted HR = 7.17, 95% CI: 3.10, 16.6) and severe lymphopenia (vs normal, adjusted HR = 36.1, 95% CI: 11.8, 110.9) as significant predictors of severe infection.
UNASSIGNED: Lymphopenia is a predictor of subsequent severe infections in patients with MPA who receive immunosuppressive therapy. These results suggest the importance of sustained infection surveillance, particularly in older patients who develop lymphopenia during strong immunosuppressive therapy.

OBJECTIVE: This study aimed to establish prediction models for respiratory-related mortality in microscopic polyangiitis (MPA) complicated by interstitial lung disease (ILD) using clinical characteristics.
METHODS: We enrolled patients with MPA with ILD between May 2005 and June 2021 in a multicentre cohort of Japanese patients with MPA (REVEAL cohort). We evaluated the demographic, clinical, laboratory, radiological findings, treatments and the presence of honeycombing 1 cm above the diaphragm using chest high-resolution CT (HRCT) on admission. We explored the risk factors predictive of respiratory-related mortality.
RESULTS: Of 115 patients, 26 cases died of respiratory-related diseases during a median follow-up of 3.8 years. Eighteen patients (69%) died due to respiratory infection, three (12%) had diffuse alveolar haemorrhage, and five (19%) had exacerbation of ILD. In univariate analysis, older age, lower percent forced vital capacity (%FVC), lower percent diffusing capacity of carbon monoxide (%DLCO), and the presence of honeycombing in the right lower lobe were identified as risk factors. Additionally, in multivariate analysis adjusted for age and treatment, %FVC, %DLCO and the presence of honeycombing in the right lower lobe were independently associated with respiratory-related mortality. We created prediction models based on the values of %FVC, %DLCO and presence of honeycombing on chest HRCT (termed \"MPF model\"). The 5-year respiratory-related death-free rate was significantly different between patients with MPA with ILD stratified by the number of risk factors based on the MPF model.
CONCLUSIONS: Our study indicates that the MPF model may help predict respiratory-related death in patients with MPA with ILD.

OBJECTIVE: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) refers to a group of small vessel inflammatory disorders. Overlapping clinical phenotypes of AAV subgroups continually provoke controversies over their diagnostic and classification criteria.
METHODS: Using the agglomerative hierarchical clustering method, we classified 210 Korean patients diagnosed with AAV into mutually exclusive clusters according to Birmingham Vasculitis Activity Score items, ANCA specificity, sex, and age. We analyzed the resulting clusters\' outcomes to investigate the clinical significance of the classification. We proposed a distance-based algorithm of patient assignment and explored its clinically relevant modification.
RESULTS: In total, 116 patients (55%) had microscopic polyangiitis, 53 (25%) had granulomatosis with polyangiitis, and 42 (20%) had eosinophilic granulomatosis with polyangiitis. Our model grouped the patients into five clusters, namely, \"limited proteinase 3 (PR3)-ANCA vasculitis,\" \"generalized PR3-ANCA vasculitis,\" \"ANCA-negative vasculitis,\" \"renal-limited vasculitis,\" and \"myeloperoxidase-ANCA vasculitis.\" Patients clustered under \"generalized PR3-ANCA vasculitis\" had a higher relapse rate (hazard ratio [HR] = 2.12, P = 0.067). The incidence of end-stage renal disease was higher in patients belonging to the \"renal-limited vasculitis\" cluster (HR=1.50, P=0.03), and those in the \"ANCA-negative vasculitis\" cluster experienced a relatively milder clinical course of AAV (mortality = 0).
CONCLUSIONS: Because the clusters were naturally derived from their distinguished phenotypes and have different clinical courses, our clustering method may be a more clinically relevant classification system for AAV, revealing its phenotypic diversity. We also proposed a simple and intuitive distance-based assignment algorithm, which can be easily modified according to specific clinical needs. Key Points • In this study with a single-center AAV cohort, we showed that AAV can be divided into five distinct subclasses with different disease courses based on the clinical and laboratory features of the patients. • Our study revealed ethnic differences in AAV manifestation and suggests that physicians may need to analyze their own AAV patients to assess the disease status of AAV patients. • We proposed a distance-based cluster membership assignment method that can be clinically modified to fit the specific purpose of grouping patients.

OBJECTIVE: To examine whether patients with ANCA-associated vasculitis (AAV) have an increased risk of cardiovascular disease in the months prior to diagnosis of AAV.
METHODS: Using a nested case-control framework, patients with granulomatosis with polyangiitis and microscopic polyangiitis were identified through the Danish Nationwide Registries from 1996 to 2021 and matched 1:3 with age- and sex-matched controls without AAV. Each control was assigned the same index date (date of AAV diagnosis) as their corresponding case. Conditional logistic regression was used to compute adjusted hazard ratios (HRs) for major adverse cardiovascular events (MACE), ischaemic heart disease, coronary angiogram, heart failure, venous thromboembolism, atrial fibrillation, ischaemic stroke, pericarditis and ventricular arrhythmias/implantable cardioverter defibrillator implantation/cardiac arrest (VA/ICD/CA) within 12 months, 6 months, 3 months, 2 months and 1 month before index date.
RESULTS: A total of 2371 patients with AAV (median age 63 years, 53.7% male) were matched with 7113 controls. The prevalence of any cardiovascular outcome and MACE within 12 months preceding index date were 10.3% and 2.4% for AAV, compared with 3.8% [HR 3.05 (95% CI 2.48-3.75)] and 1.3% [HR 1.98 (95% CI 1.39-2.82)] of controls. The risk of cardiovascular outcomes was similarly increased in temporal proximity to the diagnosis, with the highest HR at 1 month prior to index date: any cardiovascular outcome [HR 10.73 (95% CI 7.05-16.32)] and MACE [HR 5.78 (95% CI 2.67-12.52)]. In individual analysis, a significantly higher rate was observed for all outcomes (excluding VA/ICD/CA).
CONCLUSIONS: AAV disease is associated with an increased risk of cardiovascular disease in the months preceding diagnosis, which underlines the importance of early clinical vigilance towards cardiovascular disease.

OBJECTIVE: Data on ANCA-associated vasculitis (AAV) induced by anti-thyroid drugs (ATD) are scarce. We aimed to describe the characteristics and outcome of these patients in comparison to primary AAV.
METHODS: We performed a retrospective multicentre study including patients with ATD-induced AAV. We focused on ATD-induced microscopic polyangiitis (MPA) and compared them with primary MPA by matching each case with four controls by gender and year of diagnosis.
RESULTS: Forty-five patients with ATD-induced AAV of whom 24 MPA were included. ANCA were positive in 44 patients (98%), including myeloperoxidase (MPO)-ANCA in 21 (47%), proteinase 3 (PR3)-ANCA in six (13%), and double positive MPO- and PR3-ANCA in 15 (33%). Main clinical manifestations were skin involvement (64%), arthralgia (51%) and glomerulonephritis (20%). ATD was discontinued in 98% of cases, allowing vasculitis remission in seven (16%). All the remaining patients achieved remission after glucocorticoids, in combination with rituximab in 11 (30%) or cyclophosphamide in four (11%). ATD were reintroduced in seven cases (16%) without any subsequent relapse. Compared with 96 matched primary MPA, ATD-induced MPA were younger at diagnosis (48 vs 65 years, P < 0.001), had more frequent cutaneous involvement (54 vs 25%, P = 0.007), but less frequent kidney (38 vs 73%, P = 0.02), and a lower risk of relapse (adjusted HR 0.07; 95% CI 0.01, 0.65, P = 0.019).
CONCLUSIONS: ATD-induced AAV were mainly MPA with MPO-ANCA, but double MPO- and PR3-ANCA positivity was frequent. The most common manifestations were skin and musculoskeletal manifestations. ATD-induced MPA were less severe and showed a lower risk of relapse than primary MPA.