Anti-LAMP-2 Antibody Seropositivity in Children with Primary Systemic Vasculitis Affecting Medium- and Large-Sized Vessels.

Chronic primary systemic vasculitis (PSV) comprises a group of heterogeneous diseases that are broadly classified by affected blood vessel size, clinical traits and the presence (or absence) of anti-neutrophil cytoplasmic antibodies (ANCA) against proteinase 3 (PR3) and myeloperoxidase (MPO). In small vessel vasculitis (SVV), ANCA are not present in all patients, and they are rarely detected in patients with vasculitis involving medium (MVV) and large (LVV) blood vessels. Some studies have demonstrated that lysosome-associated membrane protein-2 (LAMP-2/CD107b) is a target of ANCA in SVV, but its presence and prognostic value in childhood MVV and LVV is not known. This study utilized retrospective sera and clinical data obtained from 90 children and adolescents with chronic PSV affecting small (SVV, n = 53), medium (MVV, n = 16), and large (LVV, n = 21) blood vessels. LAMP-2-ANCA were measured in time-of-diagnosis sera using a custom electrochemiluminescence assay. The threshold for seropositivity was established in a comparator cohort of patients with systemic autoinflammatory disease. The proportion of LAMP-2-ANCA-seropositive individuals and sera concentrations of LAMP-2-ANCA were assessed for associations with overall and organ-specific disease activity at diagnosis and one-year follow up. This study demonstrated a greater time-of-diagnosis prevalence and sera concentration of LAMP-2-ANCA in MVV (52.9% seropositive) and LVV (76.2%) compared to SVV (45.3%). Further, LAMP-2-ANCA-seropositive individuals had significantly lower overall, but not organ-specific, disease activity at diagnosis. This did not, however, result in a greater reduction in disease activity or the likelihood of achieving inactive disease one-year after diagnosis. The results of this study demonstrate particularly high prevalence and concentration of LAMP-2-ANCA in chronic PSV that affects large blood vessels and is seronegative for traditional ANCA. Our findings invite reconsideration of roles for autoantigens other than MPO and PR3 in pediatric vasculitis, particularly in medium- and large-sized blood vessels.

A decade of progress in juvenile idiopathic athritis treatments and outcomes in Canada: results from ReACCh-Out and the CAPRI registry.

OBJECTIVE: To assess changes in juvenile idiopathic arthritis (JIA) treatments and outcomes in Canada, comparing a 2005-2010 and a 2017-2021 inception cohorts. METHODS: Patients enrolled within three months of diagnosis in the Research in Arthritis in Canadian Children Emphasizing Outcomes (ReACCh-Out) and the Canadian Alliance of Pediatric Rheumatology Investigators Registry (CAPRI) cohorts were included. Cumulative incidences of drug starts and outcome attainment within 70 weeks of diagnosis were compared with Kaplan Meier survival analysis and multivariable Cox regression. RESULTS: The 2005-2010 and 2017-2021 cohorts included 1128 and 721 patients, respectively. JIA category distribution and baseline clinical juvenile idiopathic arthritis disease activity (cJADAS10) scores at enrolment were comparable. By 70 weeks, 6% of patients (95% CI 5, 7) in the 2005-2010 and 26% (23, 30) in the 2017-2021 cohort had started a biologic DMARD (bDMARD), and 43% (40, 47) and 60% (56, 64) had started a conventional DMARD (cDMARD), respectively. Outcome attainment was 64% (61, 67) and 83% (80, 86) for Inactive disease (Wallace criteria), 69% (66, 72) and 84% (81, 87) for minimally active disease (cJADAS10 criteria), 57% (54, 61) and 63% (59, 68) for pain control (<1/10), and 52% (47, 56) and 54% (48, 60) for a good health-related quality of life. CONCLUSION: Although baseline disease characteristics were comparable in the 2005-2010 and 2017-2021 cohorts, cDMARD and bDMARD use increased with a concurrent increase in minimally active and inactive disease. Improvements in parent and patient reported outcomes were smaller than improvements in disease activity.

Development and validation of the Kids Disability Screen for children with juvenile idiopathic arthritis: results from the CAPRI Registry.

OBJECTIVE: The aim of this study was to develop and validate a brief disability screen for children with JIA, the Kids Disability Screen (KDS). METHODS: A total of 216 children enrolled in the Canadian Alliance of Pediatric Rheumatology Investigators (CAPRI) Registry in 2017-2018 formed a development cohort, and 220 children enrolled in 2019-2020 formed a validation cohort. At every clinic visit, parents answered two questions derived from the Childhood Health Assessment Questionnaire (CHAQ): 'Is it hard for your child to run and play BECAUSE OF ARTHRITIS?' ('Hard' 0-10), and 'Does your child usually need help from you or another person BECAUSE OF ARTHRITIS?' ('Help', 0-10). We used 36-fold cross-validation and tested nine different mathematical methods to combine the answers and optimize psychometric properties. The results were confirmed in the validation cohort. RESULTS: Expressed as the mean of the two answers, KDS best balanced ease of use and psychometric properties, while a LASSO regression model combining the two answers with other patient characteristics [estimated CHAQ [eCHAQ]) had the highest responsiveness. In the validation cohort, 22.7%, 25.9% and 28.6% of patients had a score of 0 at enrolment for the KDS, eCHAQ and CHAQ, respectively. Responsiveness was 0.67, 0.74 and 0.62, respectively. Sensitivity to detect a CHAQ > 0 was 0.90 and specificity 0.56, KDS detecting some disability in 44% of children with a CHAQ = 0. CONCLUSION: This simple KDS has psychometric properties comparable with those of a full CHAQ and may be used at every clinic visit to identify those children who need a full disability assessment.

Impact of the COVID-19 pandemic on juvenile idiopathic arthritis presentation and research recruitment: results from the CAPRI registry.

OBJECTIVE: The COVID-19 pandemic has disrupted healthcare delivery and clinical research worldwide, with data from areas most affected demonstrating an impact on rheumatology care. This study aimed to characterize the impact of the pandemic on the initial presentation of JIA and JIA-related research in Canada. METHODS: Data collected from the Canadian Alliance of Pediatric Rheumatology Investigators JIA Registry from the year pre-pandemic (11 March 2019 to 10 March 2020) was compared with data collected during the first year of the pandemic (11 March 2020 to 10 March 2021). Outcomes included time from symptom onset to first assessment, disease severity at presentation and registry recruitment. Proportions and medians were used to describe categorical and continuous variables, respectively. RESULTS: The median time from symptom onset to first assessment was 138 (IQR 64-365) days pre-pandemic vs 146 (IQR 83-359) days during the pandemic. The JIA category frequencies remained overall stable (44% oligoarticular JIA pre-pandemic, 46.8% pandemic), except for systemic JIA (12 cases pre-pandemic, 1 pandemic). Clinical features, disease activity (cJADAS10), disability (CHAQ) and quality of life (JAQQ) scores were similar between the two cohorts. Pre-pandemic, 225 patients were enrolled, compared with 111 in the pandemic year, with the greatest decrease from March to June 2020. CONCLUSIONS: We did not observe the anticipated delay in time to presentation or increased severity at presentation, suggesting that, within Canada, care adapted well to provide support to new patient consults without negative impacts. The COVID-19 pandemic was associated with an initial 50% decrease in registry enrolment but has since improved.

Wide variation in glucocorticoid dosing in paediatric ANCA-associated vasculitis with renal disease: a paediatric vasculitis initiative study.

OBJECTIVES: High-dose glucocorticoids for remission-induction of ANCA-associated vasculitis are recommended and commonly used in adults, but recent studies suggest lower glucocorticoid doses can reduce toxicity without reducing efficacy. No paediatric-specific data exists to inform optimal glucocorticoid dosing in paediatric ANCA-associated vasculitis (pAAV). Our objectives were to describe glucocorticoid use in pAAV-related renal disease, and to explore associations between glucocorticoid dose, baseline patient characteristics and 12-month outcomes. METHODS: Youth <18 years with pAAV, biopsy-confirmed pauci-immune glomerulonephritis and 12-month follow-up data were included from an international paediatric vasculitis registry. Presenting features and 12-month outcomes (eGFR, glucocorticoid-related adverse effects), were compared between patients receiving no, low-moderate (≤90mg/kg) and high (>90mg/kg) cumulative intravenous methylprednisolone (IVMP), and low (<0.5mg/kg/day prednisone equivalent), moderate (0.5-1.5mg/kg/day) and high (>1.5mg/kg/day) starting doses of oral glucocorticoids. RESULTS: Among 131 patients (101 granulomatosis with polyangiitis, 30 microscopic polyangiitis), 27 (21%) received no IVMP, 64 (49%) low-moderate and 29 (22%) high-dose IVMP, while 9 (7%) received low, 75 (57%) moderate and 47 (36%) high initial doses of oral glucocorticoids. Renal failure at diagnosis (p=0.022) and plasmapheresis use (p=0.0001) were associated with high-dose IVMP. Rates of glucocorticoid-related adverse effects ranged from 15-31% across dose levels, and glucocorticoid dosing did not associate with 12-month outcomes. CONCLUSIONS: Glucocorticoid dosing for pAAV-related renal disease was highly variable, and rates of adverse effects were high across all dosing groups. A significant proportion of patients received oral glucocorticoid or IVMP doses that were discordant with current adult guidelines. Higher glucocorticoid doses did not associate with improved outcomes.

Children with systemic autoinflammatory diseases have multiple, mixed ethnicities that reflect regional ethnic diversity.

OBJECTIVES: To evaluate the ethnic diversity of children with a systemic autoinflammatory disease (SAID) in a multi-ethnic Canadian province. METHODS: Self-reported ethnicity of 149 children and adolescents with a SAID in British Columbia, Canada, was analysed for ethnic representation among individual patients, across the cohort, within particular SAIDs, and compared to provincial census data on ethnic diversity. RESULTS: Half of reported cases had a diagnosis of either PFAPA (23.5%) or an unclassifiable autoinflammatory syndrome (31.5%), with a monogenic SAID diagnosed in only 12.8% of cases. The majority of participants (73.1%) were mixed ethnicity with European and Asian heritage reported most frequently (57.0% and 23.0% of all responses, respectively). Ethnic diversity reflected regional diversity except for West Asian, Arabic, Jewish, and Eastern European heritage, which were over-represented in SAID patients, and Chinese descent, which was under-represented in our cohort compared to the general population of British Columbia. CONCLUSIONS: Results from this study show extensive multi-ethnic diversity in individual patients and across the various SAIDs inclusive of monogenic SAIDs that are frequently associated with particular ethnicities. Although not disproportionately represented, this is the first report of systemic autoinflammatory disease in Canadian children of Indigenous heritage.

Innate Control of Tissue-Reparative Human Regulatory T Cells.

Regulatory T cell (Treg) therapy is a potential curative approach for a variety of immune-mediated conditions, including autoimmunity and transplantation, in which there is pathological tissue damage. In mice, IL-33R (ST2)-expressing Tregs mediate tissue repair by producing the growth factor amphiregulin, but whether similar tissue-reparative Tregs exist in humans remains unclear. We show that human Tregs in blood and multiple tissue types produced amphiregulin, but this was neither a unique feature of Tregs nor selectively upregulated in tissues. Human Tregs in blood, tonsil, synovial fluid, colon, and lung tissues did not express ST2, so ST2+ Tregs were engineered via lentiviral-mediated overexpression, and their therapeutic potential for cell therapy was examined. Engineered ST2+ Tregs exhibited TCR-independent, IL-33-stimulated amphiregulin expression and a heightened ability to induce M2-like macrophages. The finding that amphiregulin-producing Tregs have a noneffector phenotype and are progressively lost upon TCR-induced proliferation and differentiation suggests that the tissue repair capacity of human Tregs may be an innate function that operates independently from their classical suppressive function.

Long-term outcomes and disease course of children with juvenile idiopathic arthritis in the ReACCh-Out cohort: a two-centre experience.

OBJECTIVE: To assess long-term outcomes of children with JIA diagnosed in the biologic era. METHODS: Chart review of patients prospectively enrolled in the Research in Arthritis in Canadian Children Emphasizing Outcomes inception cohort at two Canadian centres. Inactive disease and remission were defined according to Wallace criteria. RESULTS: We included 247 of 254 (97%) eligible patients diagnosed 2005-10. At the last follow-up visit at a median age of 16.9 years, 47% were in remission off medications, 25% in remission on medications and 27% had active disease; 51% were on at least one anti-rheumatic medication (22% on biologics). Patients with systemic JIA had the highest frequency of remission off medications (70%) and patients with RF-positive polyarthritis had the lowest (18%) (P <0.05 by Fisher's exact test). Among 99 patients with oligoarthritis at enrolment, 14 (14%) had an oligoarthritis extended course. Forty-five patients (18%) had at least one erosion or joint space narrowing in X-rays or MRI, and two (0.8%) required joint replacement. CONCLUSION: Relative to historical cohorts, this study suggests a reduction in JIA permanent damage, a more favourable prognosis for systemic JIA and a lower progression to oligoarthritis extended category. However, in an era of biologic therapy, one in four patients with JIA still enter adulthood with active disease and one in two still on treatment.

Associations of clinical and inflammatory biomarker clusters with juvenile idiopathic arthritis categories.

OBJECTIVE: To identify discrete clusters comprising clinical features and inflammatory biomarkers in children with JIA and to determine cluster alignment with JIA categories. METHODS: A Canadian prospective inception cohort comprising 150 children with JIA was evaluated at baseline (visit 1) and after six months (visit 2). Data included clinical manifestations and inflammation-related biomarkers. Probabilistic principal component analysis identified sets of composite variables, or principal components, from 191 original variables. To discern new clinical-biomarker clusters (clusters), Gaussian mixture models were fit to the data. Newly-defined clusters and JIA categories were compared. Agreement between the two was assessed using Kruskal-Wallis analyses and contingency plots. RESULTS: Three principal components recovered 35% (three clusters) and 40% (five clusters) of the variance in patient profiles in visits 1 and 2, respectively. None of the clusters aligned precisely with any of the seven JIA categories but rather spanned multiple categories. Results demonstrated that the newly defined clinical-biomarker lustres are more homogeneous than JIA categories. CONCLUSION: Applying unsupervised data mining to clinical and inflammatory biomarker data discerns discrete clusters that intersect multiple JIA categories. Results suggest that certain groups of patients within different JIA categories are more aligned pathobiologically than their separate clinical categorizations suggest. Applying data mining analyses to complex datasets can generate insights into JIA pathogenesis and could contribute to biologically based refinements in JIA classification.

Clinical and associated inflammatory biomarker features predictive of short-term outcomes in non-systemic juvenile idiopathic arthritis.

OBJECTIVE: To identify early predictors of disease activity at 18 months in JIA using clinical and biomarker profiling. METHODS: Clinical and biomarker data were collected at JIA diagnosis in a prospective longitudinal inception cohort of 82 children with non-systemic JIA, and their ability to predict an active joint count of 0, a physician global assessment of disease activity of ≤1 cm, and inactive disease by Wallace 2004 criteria 18 months later was assessed. Correlation-based feature selection and ReliefF were used to shortlist predictors and random forest models were trained to predict outcomes. RESULTS: From the original 112 features, 13 effectively predicted 18-month outcomes. They included age, number of active/effused joints, wrist, ankle and/or knee involvement, ESR, ANA positivity and plasma levels of five inflammatory biomarkers (IL-10, IL-17, IL-12p70, soluble low-density lipoprotein receptor-related protein 1 and vitamin D), at enrolment. The clinical plus biomarker panel predicted active joint count = 0, physician global assessment ≤ 1, and inactive disease after 18 months with 0.79, 0.80 and 0.83 accuracy and 0.84, 0.83, 0.88 area under the curve, respectively. Using clinical features alone resulted in 0.75, 0.72 and 0.80 accuracy, and area under the curve values of 0.81, 0.78 and 0.83, respectively. CONCLUSION: A panel of five plasma biomarkers combined with clinical features at the time of diagnosis more accurately predicted short-term disease activity in JIA than clinical characteristics alone. If validated in external cohorts, such a panel may guide more rationally conceived, biologically based, personalized treatment strategies in early JIA.

Current Approach to the Evaluation and Management of Incomplete Kawasaki Disease in the Emergency Department.

Kawasaki disease (KD) is one of the most common vasculitides of childhood and frequently presents to the emergency department. Although the diagnosis of KD is based on clinical criteria, children who do not fulfill the criteria but have sufficient supportive features of KD are diagnosed as having incomplete KD and warrant the same course of therapy as children with classic KD. The diagnosis of incomplete KD is challenging and requires a high index of suspicion. The purpose of this article is to review presenting features of incomplete KD and the diagnostic approach and management of children in the emergency department.

Kawasaki disease recognition and treatment.

Question If a child presents to my office with several days of fever and a few features of Kawasaki disease (KD) but does not meet the diagnostic criteria, could they still have KD and is treatment needed?Answer Presentations of KD have a range of clinical signs and symptoms. With the lack of a criterion standard test, the diagnosis of KD relies on syndrome recognition and a high index of suspicion in cases where KD does not present classically. It is still possible to have KD even if not all of the criteria are met, and these children are referred to as having incomplete forms of KD. The diagnosis of incomplete KD is usually made in a child or infant who presents with a history of prolonged fever, a few clinical criteria for KD, and other supportive features such as positive laboratory or echocardiographic findings. It is important to recognize children with incomplete forms of KD to avoid poor outcomes such as coronary artery aneurysms.

Natural history and extracutaneous involvement of congenital morphea: Multicenter retrospective cohort study and literature review.

BACKGROUND: Congenital morphea is a form of localized scleroderma that presents at birth. There is limited information on its presentation and progression. METHODS: Patients with congenital morphea were identified from five pediatric dermatology and rheumatology tertiary care centers in Canada, the United States, and Italy from 2001 to 2016. Cases from the literature were identified by searching Ovid (EMBASE and MEDLINE) from inception to June 30, 2017. Disease characteristics and prevalence of extracutaneous involvement were analyzed. RESULTS: Thirteen patients were identified from the five centers, and 13 cases were described in the literature, representing 25 patients, with one duplication. Fourteen patients (56%) were female. Median age at diagnosis was 2.9 years (interquartile range 1.2-5.1 years). Linear morphea, including en coup de sabre and Parry-Romberg syndrome, was the most common subtype observed (n = 19, 76%), followed by circumscribed (n = 5, 20%), generalized (n = 2, 8%), and mixed (n = 2, 8%). The face (n = 14, 56%), scalp (n = 8, 32%), and trunk (n = 6, 24%) were the most common locations affected. Most lesions were active at diagnosis (n = 19, 76%), but all patients with follow-up later became inactive. Extracutaneous involvement was seen in 12 (48%) patients, all of whom had linear morphea. Musculoskeletal sequelae were seen in those with linear morphea of the extremities (4/5, 80%), and neurologic involvement was seen in those with linear morphea of the head (8/13, 62%). CONCLUSION: Congenital morphea is associated with extracutaneous manifestations and delayed diagnosis. More research is needed to determine whether early recognition, monitoring, and treatment can alter the disease course.

The importance of considering monogenic causes of autoimmunity: A somatic mutation in KRAS causing pediatric Rosai-Dorfman syndrome and systemic lupus erythematosus.

OBJECTIVES: Clinicians need to be aware of the growing list of defined monogenic etiologies of autoimmune diseases. This is particularly relevant when evaluating children, as these rare monogenic forms of autoimmunity tend to present very early in life. METHODS AND RESULTS: By harnessing the transformative power of next generation sequencing, we made the unifying diagnosis of RAS-associated autoimmune leukoproliferative disease (RALD), caused by the somatic gain-of-function p.G13C KRAS mutation, in a boy with the seemingly unrelated immune dysregulatory conditions of Rosai-Dorfman and systemic lupus erythematosus (SLE). CONCLUSIONS: This case expands our understanding of the clinical phenotypes associated with the extremely rare condition of RALD, and emphasizes the importance of always considering the possibility of a monogenic cause for autoimmunity, particularly when the disease manifestations begin early in life and do not follow a typical clinical course.

The risk and nature of flares in juvenile idiopathic arthritis: results from the ReACCh-Out cohort.

OBJECTIVE: To describe probabilities and characteristics of disease flares in children with juvenile idiopathic arthritis (JIA) and to identify clinical features associated with an increased risk of flare. METHODS: We studied children in the Research in Arthritis in Canadian Children emphasizing Outcomes (ReACCh-Out) prospective inception cohort. A flare was defined as a recurrence of disease manifestations after attaining inactive disease and was called significant if it required intensification of treatment. Probability of first flare was calculated with Kaplan-Meier methods, and associated features were identified using Cox regression. RESULTS: 1146 children were followed up a median of 24 months after attaining inactive disease. We observed 627 first flares (54.7% of patients) with median active joint count of 1, physician global assessment (PGA) of 12 mm and duration of 27 weeks. Within a year after attaining inactive disease, the probability of flare was 42.5% (95% CI 39% to 46%) for any flare and 26.6% (24% to 30%) for a significant flare. Within a year after stopping treatment, it was 31.7% (28% to 36%) and 25.0% (21% to 29%), respectively. A maximum PGA >30 mm, maximum active joint count >4, rheumatoid factor (RF)-positive polyarthritis, antinuclear antibodies (ANA) and receiving disease-modifying antirheumatic drugs (DMARDs) or biological agents before attaining inactive disease were associated with increased risk of flare. Systemic JIA was associated with the lowest risk of flare. CONCLUSIONS: In this real-practice JIA cohort, flares were frequent, usually involved a few swollen joints for an average of 6 months and 60% led to treatment intensification. Children with a severe disease course had an increased risk of flare.

Pediatric vasculitis: advances in treatment.

PURPOSE OF REVIEW: This study will provide an overview of the recent advances in treatment of chronic systemic vasculitis in childhood. RECENT FINDINGS: Advances in the treatment of chronic primary systemic vasculitis have significantly improved outcomes for patients in the last several decades. Conventional life-saving treatments like cyclophosphamide and corticosteroids have predominated as mainstay therapy for severe or extensive disease; however, evidence supporting the effectiveness of newer treatments such as rituximab and other biologic agents is increasing. Improved collaboration through international registries and multicentered initiatives has enabled increased research and generation of pediatric specific data. Such efforts are essential to the development of evidence-based treatment guidelines and validated assessment tools in the future. SUMMARY: Although most of our understanding about treatment of childhood vasculitis has been derived from adult data, pediatric data continue to accumulate. Evidence for newer treatments and alternative treatment strategies is continually evolving.

The outcomes of juvenile idiopathic arthritis in children managed with contemporary treatments: results from the ReACCh-Out cohort.

OBJECTIVE: To describe clinical outcomes of juvenile idiopathic arthritis (JIA) in a prospective inception cohort of children managed with contemporary treatments. METHODS: Children newly diagnosed with JIA at 16 Canadian paediatric rheumatology centres from 2005 to 2010 were included. Kaplan-Meier survival curves for each JIA category were used to estimate probability of ever attaining an active joint count of 0, inactive disease (no active joints, no extraarticular manifestations and a physician global assessment of disease activity <10 mm), disease remission (inactive disease >12 months after discontinuing treatment) and of receiving specific treatments. RESULTS: In a cohort of 1104 children, the probabilities of attaining an active joint count of 0 exceeded 78% within 2 years in all JIA categories. The probability of attaining inactive disease exceeded 70% within 2 years in all categories, except for RF-positive polyarthritis (48%). The probability of discontinuing treatment at least once was 67% within 5 years. The probability of attaining remission within 5 years was 46-57% across JIA categories except for polyarthritis (0% RF-positive, 14% RF-negative). Initial treatment included joint injections and non-steroidal anti-inflammatory drugs for oligoarthritis, disease-modifying antirheumatic drugs (DMARDs) for polyarthritis and systemic corticosteroids for systemic JIA. CONCLUSIONS: Most children with JIA managed with contemporary treatments attain inactive disease within 2 years of diagnosis and many are able to discontinue treatment. The probability of attaining remission within 5 years of diagnosis is about 50%, except for children with polyarthritis.

Predictive utility of ANCA positivity and antigen specificity in the assessment of kidney disease in paediatric-onset small vessel vasculitis.

OBJECTIVES: The objective of this study is to evaluate whether anti-neutrophil cytoplasmic antibody (ANCA) seropositivity and antigen specificity at diagnosis have predictive utility in paediatric-onset small vessel vasculitis. METHODS: Children and adolescents with small vessel vasculitis (n=406) stratified according to the absence (n=41) or presence of ANCA for myeloperoxidase (MPO) (n=129) and proteinase-3 (PR3) (n=236) were compared for overall and kidney-specific disease activity at diagnosis and outcomes between 1 and 2 years using retrospective clinical data from the ARChiVe/Paediatric Vasculitis Initiative registry to fit generalised linear models. RESULTS: Overall disease activity at diagnosis was higher in PR3-ANCA and MPO-ANCA-seropositive individuals compared with ANCA-negative vasculitis. By 1 year, there were no significant differences, based on ANCA positivity or specificity, in the likelihood of achieving inactive disease (~68%), experiencing improvement (≥87%) or acquiring damage (~58%). Similarly, and in contrast to adult-onset ANCA-associated vasculitis, there were no significant differences in the likelihood of having a relapse (~11%) between 1 and 2 years after diagnosis. Relative to PR3-ANCA, MPO-ANCA seropositivity was associated with a higher likelihood of kidney involvement (OR 2.4, 95% CI 1.3 to 4.7, p=0.008) and severe kidney dysfunction (Kidney Disease Improving Global Outcomes (KDIGO) stages 4-5; OR 6.04, 95% CI 2.77 to 13.57, p<0.001) at onset. Nonetheless, MPO-ANCA seropositive individuals were more likely to demonstrate improvement in kidney function (improved KDIGO category) within 1 year of diagnosis than PR3-ANCA seropositive individuals with similarly severe kidney disease at onset (p<0.001). CONCLUSIONS: The results of this study suggest important paediatric-specific differences in the predictive value of ANCA compared with adult patients that should be considered when making treatment decisions in this population.

Comparing Rituximab and Cyclophosphamide in Induction Therapy for Childhood-Onset ANCA-Associated Vasculitis: An ARChiVe registry-cohort study.

OBJECTIVE: Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are chronic life-threatening vasculitides requiring substantial immunotherapy. Adult trials identified rituximab (RTX) as an alternative to cyclophosphamide (CYC) for remission-induction of GPA/MPA. Disease rarity has limited feasibility of similar trials in pediatrics. We aim to evaluate the relative efficacy and toxicity of CYC and RTX for childhood GPA/MPA through registry-based comparative evaluation. METHODS: From A Registry of Childhood Vasculitis we identified GPA/MPA patients who received induction with RTX or CYC. Pediatric vasculitis activity score (PVAS) and pediatric vasculitis damage index (pVDI) evaluated disease activity and damage. Descriptive statistics summarized patient characteristics. RTX/CYC comparisons used logistic regression for primary outcomes of post-induction remission (PVAS=0) or low disease activity (PVAS<2). Hospital admission for adverse events and pVDI were compared using logistic regression and ordinal regression, respectively. RESULTS: Among 104 patients, 43% received RTX, 46% CYC, 11% both. Treatment groups did not significantly differ for diagnosis PVAS and onset age. There was no difference in remission between groups (63% overall; OR 1.07, 95% CI: 0.45, 2.52). Hospitalizations occurred in 22% of RTX patients versus 10% on CYC (OR 2.27, 95% CI: 0.73, 7.05). The median 12-month pVDI was one in both groups (OR 0.98, 95% CI 0.43, 2.22). CONCLUSION: This is the first study comparing CYC and RTX for induction in pediatric GPA/MPA. No significant differences were shown in rates of remission, severe adverse events, or organ damage. Limitations included lack of standardized treatment regimens, retrospectivity, and lack of longitudinal adverse drug-related event data.

Consensus Treatment Plans for Severe Pediatric Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

OBJECTIVE: There is no standardized approach to the treatment of pediatric antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Because of the rarity of pediatric AAV, randomized trials have not been feasible. The present study of the Childhood Arthritis and Rheumatology Research Alliance (CARRA) was undertaken to establish consensus treatment plans (CTPs) for severe pediatric AAV to enable the future study of comparative effectiveness and safety. METHODS: A workgroup of CARRA members (rheumatologists and nephrologists) formed the AAV Workgroup. This group performed a literature review on existing evidence-based treatments and guidelines for the management of AAV. They determined that the target population for CTP development was patients <18 years of age with new-onset granulomatosis with polyangiitis (GPA), microscopic polyangiitis, or renal-limited AAV (eosinophilic GPA was excluded), with presentation confined to those with severe disease (i.e., organ- or life-threatening). Face-to-face consensus conferences employed nominal group techniques to identify treatment strategies for remission induction and remission maintenance, data elements to be systematically collected, and outcomes to be measured over time. RESULTS: The pediatric AAV Workgroup developed 2 CTPs for each of the remission induction and remission maintenance of severe AAV. A glucocorticoid-weaning regimen for induction and maintenance, a core data set, and outcome measures were also defined. A random sample of CARRA membership voted acceptance of the CTPs for remission induction and remission maintenance, with a 94% (75 of 80) and 98% (78 of 80) approval rate, respectively. CONCLUSION: Consensus methodology established standardized CTPs for treating severe pediatric AAV. These CTPs were in principle accepted by CARRA-wide membership for the evaluation of pragmatic comparative effectiveness in a long-term registry.