Von Willebrand factor antigen as a marker of disease activity in childhood-onset antineutrophil cytoplasmic antibody-associated vasculitis.

OBJECTIVE: Von Willebrand Factor (VWF) antigen plays a role in vascular inflammation and thrombosis, both important in the pathogenesis of Antineutrophil Cytoplasmic Antibody-associated vasculitis (AAV). Previous work found that VWF correlates with disease activity in childhood-onset primary CNS vasculitis. We sought to determine the relationship between VWF and disease activity over time in children with AAV. METHODS: AAV patients with more than one VWF level measured were included in this retrospective stuy, and the relationship between active vasculitis, VWF and other disease measures were analyzed. Generalized estimating equations (GEE) analysis was used to account for repeated VWF measurements within a patient. Repeated measures correlation was used to determine associations of paired laboratory observations. Diagnostic performance was evaluated using receiver operating curve (ROC) analysis. RESULTS: 732 total VWF measurements were collected in 33 AAV patients. VWF antigen levels were higher during active disease (median = 2.03 IU/ml, IQR = [1.35, 2.55]) compared with inactive disease (median = 1.18 IU/ml, IQR = [0.94, 1.53). VWF antigen was the only variable that was significantly associated with active disease (OR 3.01, p< 0.001, 95CI [2.3, 3.93]). The effect of VWF did not show a substantial difference between the disease subtypes. There was a moderate positive correlation between VWF antigen and disease activity, with an acceptable sensitivity and specificity rates. CONCLUSION: Increased VWF antigen levels correlate with active vasculitis in this paediatric-onset AAV cohort and may be used as an additional biomarker in childhood AAV.

Early systemic inflammation induces neurodevelopmental disorders: results from ARTEMIS, a French multicenter study of juvenile rheumatisms and systemic autoimmune and auto-inflammatory disorders and meta-analysis.

Prenatal immune-mediated events are known risk factors for neurodevelopmental disorders in the offspring (NDD). Although the brain continues to develop for years after birth and many postnatal factors alter the regular trajectory of neurodevelopment, little is known about the impact of postnatal immune factors. To fill this gap we set up ARTEMIS, a cohort of juvenile rheumatisms and systemic autoimmune and auto-inflammatory disorders (jRSAID), and assessed their neurodevelopment. We then complemented our results with a systematic review and meta-analysis. In ARTEMIS, we used unsupervised and supervised analysis to determine the influence of jRSAID age at onset (AO) and delay in introduction of disease-modifying therapy (DMT) on NDD (NCT04814862). For the meta-analysis, we searched MEDLINE, EMBASE, PsycINFO, Cochrane, and Web of Science up to April 2022 without any restrictions on language, or article type for studies investigating the co-occurence of jRSAID and NDD (PROSPERO- CRD42020150346). 195 patients were included in ARTEMIS. Classification tree isolated 3 groups of patients (i) A low-risk group (AO > 130 months (m)) with 5% of NDD (ii) A medium-risk group (AO < 130 m and DMT < 2 m) with 20% of NDD (iii) and a high-risk-group (AO < 130 m and DMT > 2 m) with almost half of NDD. For the meta-analysis, 18 studies encompassing a total of (i) 46,267 children with jRSAID; 213,930 children with NDD, and 6,213,778 children as controls were included. We found a positive association between jRSAID and NDD with an OR = 1.44 [95% CI 1.31; 1.57] p < 0.0001, [I2 = 66%, Tau2 = 0.0067, p < 0.01]. Several sensitivity analyses were performed without changing the results. Metaregression confirmed the importance of AO (p = 0.005). Our study supports the association between jRSAID and NDD. AO and DMT have pivotal roles in the risk of developing NDD. We plead for systematic screening of NDD in jRSAID to prevent the functional impact of NDD.

Human Papilloma Virus Vaccination in Patients with Rheumatic Diseases in France: A Study of Vaccination Coverage and Drivers of Vaccination.

Objectives: To describe human papillomavirus (HPV) vaccination practices in adolescent girls with systemic lupus erythematosus (SLE) and juvenile idiopathic arthritis (JIA) and to identify barriers to and motivators for vaccination. Methods: Cross-sectional, multicenter study on girls aged 9 to 19 years and their accompanying adults. The measurement criteria were the proportion of girls who were vaccinated against HPV, compliance with the vaccination schedule, factors associated with vaccination, and reasons for vaccination and non-vaccination through a self-administered questionnaire. Results: Seventy-one patients (16 with SLE and 55 with JIA) were included with a mean age of 13 years old (rank 11−18). According to parental questioning, 39% of patients were vaccinated against HPV or in progress (44% and 38% of SLE and JIA, respectively). This rate was 82% for the 22 patients ≥ 15 years of age. The vaccine was administered as often by a general practitioner (39%) as by a hospital pediatrician (also 39%). Two factors were significantly associated with vaccination: Older age (OR 53.68, 95% CI 5.85−429.29, p < 0.001) and previous hepatitis B vaccination (OR 4.97, 95% CI 1.03−24.01, p = 0.040). Recommendation of the vaccine by a health professional and fear of HPV-related diseases were the main facilitators. Lack of knowledge about the vaccine, lack of recommendation by a health professional, and fear of vaccine side effects were the main barriers. Conclusions: HPV vaccination coverage remains insufficient among patients with autoimmune disease. Education and awareness of health professionals about HPV infections are crucial elements in vaccine acceptance.

An Update on Childhood-Onset Takayasu Arteritis.

Takayasu Arteritis (TAK) is a rare large vessel vasculitis affecting the aorta and its major branches. The heterogeneous and often severe clinical manifestations result from systemic and local inflammation as well as end-organ ischemia. Disease flares are common and contribute to accrued damage over time with significant morbidity and mortality. Newer understanding of the pathogenesis in TAK has paved the way for the use of pathway targeting agents such as tumor necrosis factor (TNF)α- or interleuking (IL)-6-inhibitors with improved disease control. Nevertheless, long-term data are lacking, particularly in children; prognosis often remains guarded and the disease burden high. This article aims at providing a comprehensive review of childhood-onset TAK with a focus on recent publications.

Outcomes of SARS-CoV-2 infection among children and young people with pre-existing rheumatic and musculoskeletal diseases.

OBJECTIVES: Some adults with rheumatic and musculoskeletal diseases (RMDs) are at increased risk of COVID-19-related death. Excluding post-COVID-19 multisystem inflammatory syndrome of children, children and young people (CYP) are overall less prone to severe COVID-19 and most experience a mild or asymptomatic course. However, it is unknown if CYP with RMDs are more likely to have more severe COVID-19. This analysis aims to describe outcomes among CYP with underlying RMDs with COVID-19. METHODS: Using the European Alliance of Associations for Rheumatology COVID-19 Registry, the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry, and the CARRA-sponsored COVID-19 Global Paediatric Rheumatology Database, we obtained data on CYP with RMDs who reported SARS-CoV-2 infection (presumptive or confirmed). Patient characteristics and illness severity were described, and factors associated with COVID-19 hospitalisation were investigated. RESULTS: 607 CYP with RMDs <19 years old from 25 different countries with SARS-CoV-2 infection were included, the majority with juvenile idiopathic arthritis (JIA; n=378; 62%). Forty-three (7%) patients were hospitalised; three of these patients died. Compared with JIA, diagnosis of systemic lupus erythematosus, mixed connective tissue disease, vasculitis, or other RMD (OR 4.3; 95% CI 1.7 to 11) or autoinflammatory syndrome (OR 3.0; 95% CI 1.1 to 8.6) was associated with hospitalisation, as was obesity (OR 4.0; 95% CI 1.3 to 12). CONCLUSIONS: This is the most significant investigation to date of COVID-19 in CYP with RMDs. It is important to note that the majority of CYP were not hospitalised, although those with severe systemic RMDs and obesity were more likely to be hospitalised.

Efficacy and tolerance of corticosteroids and methotrexate in patients with juvenile dermatomyositis: a retrospective cohort study.

OBJECTIVES: To assess the efficacy and tolerance of the conventional first-line treatment by MTX and CS in patients with JDM regardless of severity. METHODS: We conducted a monocentric retrospective study of patients with newly diagnosed JDM treated with MTX and CS from 2012 to 2020. The proportion of clinically inactive disease (CID) within 6 months of MTX initiation was evaluated using both Paediatric Rheumatology International Trials Organisation (PRINTO) criteria (evaluating muscle inactive disease) and DAS (evaluating skin inactive disease). We compared responders and non-responders using univariate analyses. RESULTS: Forty-five patients with JDM, out of which 30 (67%) severe JDM, were included. After 6 months of treatment with MTX and CS, complete CID, muscle CID and skin CID were achieved in 14/45 (31%), 19/45 (42%) and 15/45 (33%) patients, respectively. The absence of myositis-specific (MSA) or myositis-associated autoantibodies (MAA) at diagnosis was associated with a better overall, cutaneous and muscular therapeutic response, compared with antibody-positive forms (P < 0.01). Requirement for ICU (P = 0.029) and cutaneous ulcerations (P = 0.018) were associated with a less favourable muscle response. MTX was stopped due to intolerance in six patients (13%) before month 6. CONCLUSIONS: Conventional first-line treatment with MTX was not efficient in a large subset of JDM patients, especially in patients with MSA-positive forms, and in patients with severe JDM. Larger, multicentre cohorts are required to confirm these data and to identify new predictive biomarkers of MTX response, in order to treat patients with JDM as early as possible with appropriate targeted drugs.

Curation and expansion of Human Phenotype Ontology for defined groups of inborn errors of immunity.

BACKGROUND: Accurate, detailed, and standardized phenotypic descriptions are essential to support diagnostic interpretation of genetic variants and to discover new diseases. The Human Phenotype Ontology (HPO), extensively used in rare disease research, provides a rich collection of vocabulary with standardized phenotypic descriptions in a hierarchical structure. However, to date, the use of HPO has not yet been widely implemented in the field of inborn errors of immunity (IEIs), mainly due to a lack of comprehensive IEI-related terms. OBJECTIVES: We sought to systematically review available terms in HPO for the depiction of IEIs, to expand HPO, yielding more comprehensive sets of terms, and to reannotate IEIs with HPO terms to provide accurate, standardized phenotypic descriptions. METHODS: We initiated a collaboration involving expert clinicians, geneticists, researchers working on IEIs, and bioinformaticians. Multiple branches of the HPO tree were restructured and extended on the basis of expert review. Our ontology-guided machine learning coupled with a 2-tier expert review was applied to reannotate defined subgroups of IEIs. RESULTS: We revised and expanded 4 main branches of the HPO tree. Here, we reannotated 73 diseases from 4 International Union of Immunological Societies-defined IEI disease subgroups with HPO terms. We achieved a 4.7-fold increase in the number of phenotypic terms per disease. Given the new HPO annotations, we demonstrated improved ability to computationally match selected IEI cases to their known diagnosis, and improved phenotype-driven disease classification. CONCLUSIONS: Our targeted expansion and reannotation presents enhanced precision of disease annotation, will enable superior HPO-based IEI characterization, and hence benefit both IEI diagnostic and research activities.

Overview of Imaging in Adult- and Childhood-onset Takayasu Arteritis.

Takayasu arteritis is an idiopathic large-vessel vasculitis that affects young adults and children and can lead to ischemia and end-organ damage. Vascular imaging is crucial for diagnosis, assessment of disease extent, and management of the disease. Here we critically review evidence for the clinical use of the different imaging modalities: conventional angiography, magnetic resonance imaging, computed tomography, Doppler ultrasound, and 18fluorodeoxyglucose positron emission tomography. We thereby focus on their clinical applicability, challenges, and specific use in children.

A young girl with severe polyarteritis nodosa successfully treated with tocilizumab: a case report.

BACKGROUND: Childhood Polyarteritis nodosa (PAN) is a systemic vasculitis with necrotizing inflammation of medium- and small-sized arteries. Disease evolution may be severe and refractory to standard treatment including prednisone, azathioprine and cyclophosphamide. CASE PRESENTATION: We present the case of a young girl with severe PAN resulting in progressive ischemia and necrosis of fingers and toes. Biological work-up revealed increased acute phase reactants and interleukin-6 levels. She was only partially controlled despite high-dose corticosteroids and cyclophosphamide infusions, and eventually achieved rapid improvement and sustained remission on tocilizumab. Further, we review the current evidence of the interleukin-6-inhibitor tocilizumab for the treatment of PAN. CONCLUSION: Tocilizumab may be an efficient therapeutic option in a subset of treatment-refractory children with PAN.

Myocardial involvement in children with post-COVID multisystem inflammatory syndrome: a cardiovascular magnetic resonance based multicenter international study-the CARDOVID registry.

BACKGROUND: Recent evidence shows an association between coronavirus disease 2019 (COVID-19) infection and a severe inflammatory syndrome in children. Cardiovascular magnetic resonance (CMR) data about myocardial injury in children are limited to small cohorts. The aim of this multicenter, international registry is to describe clinical and cardiac characteristics of multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19 using CMR so as to better understand the real extent of myocardial damage in this vulnerable cohort. METHODS AND RESULTS: Hundred-eleven patients meeting the World Health Organization criteria for MIS-C associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), having clinical cardiac involvement and having received CMR imaging scan were included from 17 centers. Median age at disease onset was 10.0 years (IQR 7.0-13.8). The majority of children had COVID-19 serology positive (98%) with 27% of children still having both, positive serology and polymerase chain reaction (PCR). CMR was performed at a median of 28 days (19-47) after onset of symptoms. Twenty out of 111 (18%) patients had CMR criteria for acute myocarditis (as defined by the Lake Louise Criteria) with 18/20 showing subepicardial late gadolinium enhancement (LGE). CMR myocarditis was significantly associated with New York Heart Association class IV (p = 0.005, OR 6.56 (95%-CI 1.87-23.00)) and the need for mechanical support (p = 0.039, OR 4.98 (95%-CI 1.18-21.02)). At discharge, 11/111 (10%) patients still had left ventricular systolic dysfunction. CONCLUSION: No CMR evidence of myocardial damage was found in most of our MIS-C cohort. Nevertheless, acute myocarditis is a possible manifestation of MIS-C associated with SARS-CoV-2 with CMR evidence of myocardial necrosis in 18% of our cohort. CMR may be an important diagnostic tool to identify a subset of patients at risk for cardiac sequelae and more prone to myocardial damage. CLINICAL TRIAL REGISTRATION: The study has been registered on ClinicalTrials.gov, Identifier NCT04455347, registered on 01/07/2020, retrospectively registered.

Serious adverse events in children with juvenile idiopathic arthritis and other rheumatic diseases on tocilizumab - a real-world experience.

OBJECTIVES: To assess the incidence rate and type of serious adverse events (SAE) in children with rheumatic inflammatory diseases treated with the interleukin 6 blocker tocilizumab (TCZ). METHODS: A retrospective review of all consecutive patients diagnosed with an inflammatory rheumatic disease and receiving at least one dose of TCZ was performed in two French tertiary pediatric rheumatology centers between 01/2007 and 06/2019. SAE were defined as a life-threatening event and/or an event requiring hospital admission, leading to permanent disability or treatment discontinuation. RESULTS: One hundred four children (64 female) were included. Most children suffered from systemic (n = 43) or polyarticular-course juvenile idiopathic arthritis (n = 43). Median age at TCZ start was 8.9 years (IQR 4.7 - 12.1), most children had received prednisone (81%), and/or a biologic agent (84%) prior to TCZ. Median TCZ treatment duration was 1.6 years (IQR 0.5 - 2.7), total TCZ exposure 215 patient years. Thirty-three SAE were observed in 26 (25%) children (SAE 15.3/100 patient years), mostly infections and infusion reactions. Children with SAE were significantly younger at disease onset (p = 0.034) and TCZ initiation (p = 0.016). Children experiencing infusion reactions were more likely to have systemic JIA or another autoinflammatory disease (p = 0.021), they all had active disease. At last follow up, 61 (59%) children remained on TCZ. CONCLUSION: In this cohort, SAE and most commonly serious infections were observed in a quarter of children. Severe infusion reactions were associated with persistently active autoinflammatory disease. Ongoing careful monitoring of TCZ-treated patients, especially young children with marked systemic inflammation is required.

Childhood-onset Takayasu Arteritis.

Childhood-onset Takayasu Arteritis (cTAK) is a rare, large-vessel type of vasculitis seen in children, mainly affecting the aorta and its major branches. Clinical manifestations are often severe and arise as a result of systemic and local inflammation, along with end-organ ischemia. Disease flares are common and the disease burden is high, with a significant rate of morbidity and mortality. Recent advances in understanding the underlying disease pathobiology resulted in the use of pathway-targeting agents, such as TNF- or IL-6 inhibitors with improved disease control. Nonetheless, the prognosis often remains guarded and the accrued damage is significant. This review aims at summarizing the recent evidence and observations regarding this condition, with a focus on pediatric publications.

Patterns of joint involvement in juvenile idiopathic arthritis and prediction of disease course: A prospective study with multilayer non-negative matrix factorization.

BACKGROUND: Joint inflammation is the common feature underlying juvenile idiopathic arthritis (JIA). Clinicians recognize patterns of joint involvement currently not part of the International League of Associations for Rheumatology (ILAR) classification. Using unsupervised machine learning, we sought to uncover data-driven joint patterns that predict clinical phenotype and disease trajectories. METHODS AND FINDINGS: We analyzed prospectively collected clinical data, including joint involvement using a standard 71-joint homunculus, for 640 discovery patients with newly diagnosed JIA enrolled in a Canada-wide study who were followed serially for five years, treatment-naïve except for nonsteroidal anti-inflammatory drugs (NSAIDs) and diagnosed within one year of symptom onset. Twenty-one patients had systemic arthritis, 300 oligoarthritis, 125 rheumatoid factor (RF)-negative polyarthritis, 16 RF-positive polyarthritis, 37 psoriatic arthritis, 78 enthesitis-related arthritis (ERA), and 63 undifferentiated arthritis. At diagnosis, we observed global hierarchical groups of co-involved joints. To characterize these patterns, we developed sparse multilayer non-negative matrix factorization (NMF). Model selection by internal bi-cross-validation identified seven joint patterns at presentation, to which all 640 discovery patients were assigned: pelvic girdle (57 patients), fingers (25), wrists (114), toes (48), ankles (106), knees (283), and indistinct (7). Patterns were distinct from clinical subtypes (P < 0.001 by χ2 test) and reproducible through external data set validation on a 119-patient, prospectively collected independent validation cohort (reconstruction accuracy Q2 = 0.55 for patterns; 0.35 for groups). Some patients matched multiple patterns. To determine whether their disease outcomes differed, we further subdivided the 640 discovery patients into three subgroups by degree of localization-the percentage of their active joints aligning with their assigned pattern: localized (≥90%; 359 patients), partially localized (60%-90%; 124), or extended (<60%; 157). Localized patients more often maintained their baseline patterns (P < 0.05 for five groups by permutation test) than nonlocalized patients (P < 0.05 for three groups by permutation test) over a five-year follow-up period. We modelled time to zero joints in the discovery cohort using a multivariate Cox proportional hazards model considering joint pattern, degree of localization, and ILAR subtype. Despite receiving more intense treatment, 50% of nonlocalized patients had zero joints at one year compared to six months for localized patients. Overall, localized patients required less time to reach zero joints (partial: P = 0.0018 versus localized by log-rank test; extended: P = 0.0057). Potential limitations include the requirement for patients to be treatment naïve (except NSAIDs), which may skew the patient cohorts towards milder disease, and the validation cohort size precluded multivariate analyses of disease trajectories. CONCLUSIONS: Multilayer NMF identified patterns of joint involvement that predicted disease trajectory in children with arthritis. Our hierarchical unsupervised approach identified a new clinical feature, degree of localization, which predicted outcomes in both cohorts. Detailed assessment of every joint is already part of every musculoskeletal exam for children with arthritis. Our study supports both the continued collection of detailed joint involvement and the inclusion of patterns and degrees of localization to stratify patients and inform treatment decisions. This will advance pediatric rheumatology from counting joints to realizing the potential of using data available from uncovering patterns of joint involvement.

Increased Arterial Stiffness Adversely Affects Left Ventricular Mechanics in Patients With Pediatric Takayasu Arteritis From a Toronto Cohort.

BACKGROUND/OBJECTIVE: Takayasu arteritis (TA) is characterized by extensive aortic, large and midsize arterial wall inflammation. The aim of this study was to assess the morphological and elastic properties of the aorta and large arteries and the impact on left ventricular (LV) mechanics in children with TA. METHODS: Seven pediatric TA patients (6 female patients, 13.8 ± 3.2 years) were assessed with magnetic resonance imaging, vascular ultrasound, applanation tonometry, and echocardiography from February 2015 until July 2017 and compared with 7 age- and sex-matched controls. Takayasu arteritis disease activity was assessed clinically by the Pediatric Vasculitis Activity Score (PVAS). RESULTS: Pediatric TA patients showed increased carotid-to-radial artery pulse wave velocity (8.1 ± 1.8 vs. 6.4 ± 0.6 m/s, p = 0.03) and increased carotid-to-femoral artery pulse wave velocity (8.3 ± 1.9 vs. 5.1 ± 0.8 m/s, p < 0.01) when compared with controls. Patients demonstrated increased LV mass index (74.3 ± 18.8 vs. 56.3 ± 10.9 g/m, p = 0.04), altered myocardial deformation with increased basal rotation (-9.8 ± 4.5 vs. -4.0 ± 2.0 degrees, p = 0.01) and torsion (19.9 ± 8.1 vs. 9.1 ± 3.1 degrees, p = 0.01), and impaired LV diastolic function with decreased mitral valve E/A ratio (1.45 ± 0.17 vs. 2.40 ± 0.84, p = 0.01), increased mitral valve E/E' ratio (6.8 ± 1.4 vs. 4.9 ± 0.7, p < 0.01), and increased pulmonary vein A-wave velocity (26.7 ± 5.7 vs. 16.8 ± 3.3 cm/s, p = 0.03). Carotid-to-radial artery pulse wave velocity was associated with systolic (R = 0.94, p < 0.01), diastolic (R = 0.85, p = 0.02), and mean blood pressure (R = 0.91, p < 0.01), as well as disease activity by PVAS (R = 0.75, p = 0.05). The PVAS was associated with carotid-to-radial artery pulse wave velocity (R = 0.75, p = 0.05), as well as systolic (R = 0.84, p = 0.02), diastolic (R = 0.82, p = 0.03), and mean blood pressure (R = 0.84, p = 0.02). CONCLUSIONS: Increased arterial stiffness is present in pediatric TA patients and associated with increased blood pressure and TA disease activity. Pediatric TA patients demonstrate altered LV mechanics, LV hypertrophy, and impaired diastolic function.

Presentation and Disease Course of Childhood-Onset Versus Adult-Onset Takayasu Arteritis.

OBJECTIVE: To compare the clinical features, efficacy and safety of treatment regimens, and outcomes of childhood- and adult-onset Takayasu arteritis (TAK). METHODS: The study was designed as a retrospective cohort study comparing patients with childhood-onset TAK (from 1986 onward) to patients with adult-onset TAK (from 1988 onward) who were followed up until 2014 or 2015 at 4 centers in Ontario, Canada. Demographic, clinical, laboratory, and angiographic features, treatment regimens, and outcomes were recorded throughout the course of the disease. Disease activity and damage scores were completed retrospectively. RESULTS: Twenty-nine children and 48 adults (median age at diagnosis 12.1 years and 31.2 years, respectively) were included. A lower predominance of females was observed among the childhood-onset TAK cohort (76% versus 100% of patients with adult-onset TAK; P < 0.01), and children had a shorter delay to diagnosis (median 6.0 months versus 12.2 months for adults; P = 0.03). The distribution of vascular involvement was also different, with children having significantly more aortic and renal artery involvement and a higher frequency of arterial hypertension. Relapses in the first year after diagnosis were common both in children (39%) and in adults (28%). Two children, but no adults, died. CONCLUSION: Childhood-onset TAK has a lower female predominance and a higher frequency of aortic and renal involvement compared to adult-onset TAK. Relapses and disease burden were high in both groups, corroborating the need for careful monitoring of disease activity and aggressive therapeutic management.

Risk of Serious Infections Associated with Biologic Agents in Juvenile Idiopathic Arthritis: A Systematic Review and Meta-Analyses.

OBJECTIVE: To assess whether treatment with biologic response modifying agents during clinical trial study periods increases the risk of serious infections in children with juvenile idiopathic arthritis (JIA). STUDY DESIGN: A systematic literature review using Medline, Embase, Cochrane library, and the clinical trial registry was performed up to July 2017. Random effects meta-analyses were used to compare rates of serious infections in children with JIA given biologic agents compared with controls, and the pooled relative risk calculated. Subanalyses were performed for different biologic agent classes. RESULTS: In total, 19 trials accounting for 21 individual studies were included (11 for tumor necrosis factor-alpha inhibitors [n = 814 patients], 3 for interleukin-6 inhibitors [n = 318], 6 for interleukin-1 inhibitors [n = 353], and 1 for selective T-lymphocyte costimulation modulators [n = 122]). Patients (68% female) had a mean age of 10.8 years. Seventeen serious infections were reported among 810 children receiving biologic agents and 15 among 797 controls. The most frequent infections were bronchopulmonary and varicella. No statistically significant difference in risk of serious infections was found between children receiving biologic agents compared with control groups (pooled relative risk = 1.13; 95% CI [0.63, 2.03]) during the trial study periods. The risk remained nonsignificant when evaluating the different classes of biologic agents separately. However, the analyses were underpowered to detect differences in the risk of serious infections overall or differences between classes of biologic agents. CONCLUSIONS: In this systematic review and meta-analyses, serious infections were uncommon and not significantly increased among patients with JIA receiving biologic agents compared with controls. However, the analyses were underpowered and study periods were relatively short. Ongoing careful monitoring for serious infections remains necessary for all patients with JIA, and particularly those receiving biologic agents.