Successful Management of Febrile Infection-Related Epilepsy Syndrome Using Cytokine-Directed Therapy.

Here we describe a pediatric patient with febrile infection-related epilepsy syndrome with a good functional and neurologic outcome after treatment with early and aggressive cytokine-directed immunomodulatory therapy and a seizure management strategy that intentionally avoided a barbiturate coma. A 5-year-old previously healthy male presented with staring, behavioral arrest, and encephalopathy evolving to super-refractory status epilepticus. He had had onset of fever 5 days prior. He was treated with early and aggressive immunomodulatory therapy targeted to his evolving cytokine profile. He was also treated with the ketogenic diet, antiseizure medications, and continuous anesthetic infusions. Pentobarbital was purposely avoided. Now, 2½ years later, he attends mainstream school, has attention-deficit hyperactivity disorder (ADHD), mild neurocognitive impairment, and well-controlled epilepsy. By using cytokine-directed immunotherapy and avoiding a barbiturate coma, we were able to successfully treat a pediatric patient with febrile infection-related epilepsy syndrome and achieve a good outcome.

Small fiber neuropathy in children, adolescents, and young adults with chronic orthostatic intolerance and postural orthostatic tachycardia syndrome: A retrospective study.

PURPOSE: To determine in children, adolescent and young adult (CAYA) patients presenting with Orthostatic Intolerance (OI) or Postural Orthostatic Tachycardia Syndrome (POTS) associated with the additional symptoms of neuropathic discomfort (pain, paresthesia and/or allodynia): 1) the incidence of small fiber neuropathy, and 2) assess if there was serologic evidence for an underlying inflammatory or autoimmune state. METHODS: A cohort of 109 CAYA patients with the above symptoms underwent epidermal skin biopsy for nerve fiber density. Blood biomarkers for inflammation were tested (CRP, ESR, ANA, complement (C3), thyroid function testing with antibodies (thyroid peroxidase antibody and thyroglobulin antibody), and cytokine panel 13). Patients completed a Quality of Health questionnaire. Statistical analysis was performed using Wilcoxon rank sum tests. RESULTS: In CAYA patients with OI or POTS and neuropathic symptoms, skin biopsy for small fiber neuropathy was abnormal in 53 %. The sample population was predominantly female and Caucasian with moderately decreased perceived quality of health. OI /POTS patients with small fiber neuropathy had a 3-fold probability of having a positive ANA or anti-thyroid antibody, suggesting an underlying autoimmune or inflammatory process. CONCLUSION: Our data suggest a link between OI and POTS and small fiber neuropathy. Small fiber neuropathy was found by skin biopsy in over half of the patients tested. OI and Postural orthostatic tachycardia patients with small fiber neuropathy expressed multiple markers suggesting an underlying autoimmune or inflammatory process. Future research will be done to evaluate the symptomatic implication of SFN and whether immune or pharmacologic manipulation can alter patient symptoms.

Behavioral health outcomes and social determinants of health in children with diabetes and juvenile arthritis.

Objective: Children with chronic illnesses, including arthritis, are at increased risk for adverse psychosocial outcomes influenced by social determinants of health (SDOH). Comparing psychosocial outcomes in families affected by juvenile arthritis compared to other chronic illnesses may help identify areas in need of special attention vs areas that may be addressed through adopting other disease examples' care models. We examined child and parent behavioral health outcomes for families with juvenile arthritis compared to diabetes, accounting for SDOH. Methods: Secondary data analysis of the National Survey of Children's Health including 365 children (<18yrs) with arthritis and 571 children with diabetes. Psychosocial outcomes were depression, anxiety, ADHD, physical pain, behavioral problems, and treatment for mental health. School outcomes were school engagement, school absence, involvement in clubs/organization, and involvement in organized activities. Parent outcomes were family resilience, emotional support, coping with daily demands of raising a child, job change due to problems with childcare, and parent mental health. SDOH variables were food insecurity, food/cash assistance, unsafe neighborhood, detracting neighborhood elements, parent education, households earning <100% of the federal poverty line. Logistic regression analyses were utilized to examine variation in child and parent outcomes, variation in SDOH, and the role of SDOH. Results: Children with arthritis experienced significantly more physical pain, anxiety, depression, ADHD, and behavior problems compared to children with diabetes. Children with arthritis were more likely to see a mental health professional and get treatment for problems with emotions/behaviors. When considering SDOH, children with arthritis were still more likely to experience adverse psychosocial outcomes but were no longer more likely to get treatment. Children with arthritis had increased likelihood of school absence and were less involved in organized activities than children with diabetes. Parents of children with arthritis had poorer mental health than parents of children with diabetes. SDOH were more prevalent in children with arthritis than children with diabetes. Conclusions: Increased risk for adverse psychosocial outcomes in youth with arthritis compared to youth with diabetes indicates a need to mirror endocrinology models of care in rheumatology clinics. The role of SDOH highlights the need for regular SDOH screening in clinic.

Clinical outcomes and safety of anakinra in the treatment of multisystem inflammatory syndrome in children: a single center observational study.

BACKGROUND AND OBJECTIVE: Evidence for the treatment of multisystem inflammatory syndrome in children (MIS-C) is lacking. Anakinra, which targets IL-1-mediated inflammation, is reserved for refractory cases of MIS-C; however, its use in the treatment of MIS-C is not clearly established. PATIENTS AND METHODS: To examine a role for anakinra in MIS-C, we performed a single center observational cohort study of all MIS-C patients diagnosed at our children's hospital from May 15 to November 15, 2020. Demographics, clinical features, diagnostic testing, and cardiac function parameters were compared between MIS-C patients treated with intravenous immunoglobulin (IVIG) monotherapy and IVIG with anakinra (IVIG + anakinra). RESULTS: Among 46 patients with confirmed MIS-C, 32 (70%) were in the IVIG + anakinra group, of which 9 (28%) were also given corticosteroids (CS). No patients were treated with anakinra alone. MIS-C patients in the IVIG + anakinra group were enriched in a CV shock phenotype (p = 0.02), and those with CV shock were treated with higher doses of anakinra for a longer duration. Furthermore, MIS-C patients in the IVIG + anakinra group exhibited improvements in fever and cardiac function with or without CS. No significant adverse events were observed, and no differences in IL-1ß levels were found among MIS-C patients in the IVIG + anakinra group. CONCLUSIONS: Anakinra treatment, which was co-administered with IVIG primarily in patients with severe MIS-C, was associated with improvements in fever and cardiac function, and demonstrated a favorable side-effect profile. These findings suggest a role for adjunctive anakinra in the treatment of severe MIS-C.

The Challenges of Identifying Fibromyalgia in Adolescents.

Aim: Fibromyalgia (FM) is a noninflammatory disorder of the nervous system characterized by widespread musculoskeletal pain and somatic complaints of at least 3 months duration. There are no current diagnostic criteria for fibromyalgia in children to guide clinicians in recognition, thus leading to many subspecialty referrals and extensive imaging and tests. The purpose of this retrospective review is to compare two diagnostic criteria for juvenile fibromyalgia. Methods: A retrospective chart review of 20 children diagnosed with juvenile fibromyalgia from a singular pain physician practice was performed. Both the Yunus diagnostic criteria and the 2016 American College of Rheumatology (ACR) diagnostic criteria were applied and compared. Results: 85% of patients met criteria for fibromyalgia under both criteria. 15% of patients met only ACR criteria as the Yunus criteria excluded those with underlying conditions. Of the children who fulfilled criteria with use of both diagnostic tools, this cohort reported a high somatic symptom burden as demonstrated by the ACR symptom severity scales of 12 and satisfaction of at least 4 Yunus and Masi minor criteria on average. Widespread pain was noted with an ACR Widespread Pain Index (WPI) of 7, and tender points were 4.8 on average across the cohort. Effective therapeutic regimens among patients varied widely from medical monotherapy to multimodal treatment. Patients presented with pain for 1.8 yrs on average prior to a diagnosis. All of the cohort had a normal laboratory evaluation; half the cohort received additional imaging and testing. Conclusion: This case series suggests the need for an updated diagnostic tool for pediatric fibromyalgia to facilitate recognition and treatment.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Kawasaki Disease.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of Kawasaki disease (KD), focusing on clinical scenarios more commonly addressed by rheumatologists. METHODS: Sixteen clinical questions regarding diagnostic testing, treatment, and management of KD were developed in the Patient/Population, Intervention, Comparison, and Outcomes (PICO) question format. Systematic literature reviews were conducted for each PICO question. We used the Grading of Recommendations, Assessment, Development and Evaluation method to assess the quality of evidence and formulate recommendations. Each recommendation required consensus from at least 70% of the Voting Panel. RESULTS: We present 1 good practice statement, 11 recommendations, and 1 ungraded position statement to guide the management of KD and clinical scenarios of suspected KD. These recommendations for KD are focused on situations in which input from rheumatologists may be requested by other managing specialists, such as in cases of treatment-refractory, severe, or complicated KD. The good practice statement affirms that all patients with KD should receive initial treatment with intravenous immunoglobulin (IVIG). In addition, we developed 7 strong and 4 conditional recommendations for the management of KD or suspected KD. Strong recommendations include prompt treatment of incomplete KD, treatment with aspirin, and obtaining an echocardiogram in the setting of unexplained macrophage activation syndrome or shock. Conditional recommendations include use of IVIG with other adjuvant agents for patients with KD and high-risk features of IVIG resistance and/or coronary artery aneurysms. These recommendations endorse minimizing risk to the patient by using established therapy promptly at disease onset and identifying situations in which adjunctive therapy may be warranted. CONCLUSION: These recommendations provide guidance regarding diagnostic strategies, use of pharmacologic agents, and use of echocardiography in patients with suspected or confirmed KD.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Kawasaki Disease.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of Kawasaki disease (KD), focusing on clinical scenarios more commonly addressed by rheumatologists. METHODS: Sixteen clinical questions regarding diagnostic testing, treatment, and management of KD were developed in the Patient/Population, Intervention, Comparison, and Outcomes (PICO) question format. Systematic literature reviews were conducted for each PICO question. We used the Grading of Recommendations, Assessment, Development and Evaluation method to assess the quality of evidence and formulate recommendations. Each recommendation required consensus from at least 70% of the Voting Panel. RESULTS: We present 1 good practice statement, 11 recommendations, and 1 ungraded position statement to guide the management of KD and clinical scenarios of suspected KD. These recommendations for KD are focused on situations in which input from rheumatologists may be requested by other managing specialists, such as in cases of treatment-refractory, severe, or complicated KD. The good practice statement affirms that all patients with KD should receive initial treatment with intravenous immunoglobulin (IVIG). In addition, we developed 7 strong and 4 conditional recommendations for the management of KD or suspected KD. Strong recommendations include prompt treatment of incomplete KD, treatment with aspirin, and obtaining an echocardiogram in the setting of unexplained macrophage activation syndrome or shock. Conditional recommendations include use of IVIG with other adjuvant agents for patients with KD and high-risk features of IVIG resistance and/or coronary artery aneurysms. These recommendations endorse minimizing risk to the patient by using established therapy promptly at disease onset and identifying situations in which adjunctive therapy may be warranted. CONCLUSION: These recommendations provide guidance regarding diagnostic strategies, use of pharmacologic agents, and use of echocardiography in patients with suspected or confirmed KD.

Autoantibody cluster analysis in juvenile lupus nephritis.

OBJECTIVE: Demographics, clinical features, and biomarkers do not consistently anticipate risk of end-stage renal disease (ESRD) in juvenile lupus nephritis (LN). Here, the existence of autoantibody clusters predictive of ESRD was explored in a cohort of biopsy-proven juvenile LN. METHODS: A retrospective chart review was performed of patients with juvenile systemic lupus erythematosus (jSLE) and biopsy-confirmed LN. Primary endpoints were ESRD and mortality. Patients were included for K-medians cluster analysis if they had a complete autoantibody profile, which included ANA titer, anti-dsDNA, anti-Smith, anti-RNP, anti-Ro/SSA, anti-La/SSB. Chi-square test was used for categorical variables and one-way ANOVA for continuous measures. Significance was p<0.05. RESULTS: Fifty-three met inclusion criteria, of which 45 were female and 37 were black. Over 80% developed LN within one year of jSLE onset and more than half (n=29) had LN at diagnosis of jSLE. Six developed ESRD. No mortalities were reported. Forty-six had a complete autoantibody profile, including four with ESRD. Three clusters were identified. Group 1 (n=8) was defined by anti-dsDNA; group 2 (n=28) by high-titer ANA (>1:1280), anti-Smith, anti-RNP, and anti-Ro/SSA; and group 3 (n=10) by anti-dsDNA and anti-Ro/SSA. There was no difference between the groups in demographics, jSLE manifestations, or markers of renal function. One in group 2 and three in group 3 developed ESRD. Those in group 3 were younger at diagnosis of LN (p=0.084) and had the highest frequency of ESRD (p=0.025). CONCLUSION: Cluster analysis revealed the highest frequency of ESRD in the group with LN defined by anti-Ro/SSA and anti-dsDNA co-positivity. Key Points • Lupus nephritis commonly is present at diagnosis of juvenile systemic lupus erythematosus or develops within the first year. • End-stage renal disease was more frequent in the cluster defined by anti-dsDNA and anti-Ro/SSA co-positivity; patients with this profile may benefit from more aggressive immunosuppression.

Using a Multi-Institutional Pediatric Learning Health System to Identify Systemic Lupus Erythematosus and Lupus Nephritis: Development and Validation of Computable Phenotypes.

BACKGROUND AND OBJECTIVES: Performing adequately powered clinical trials in pediatric diseases, such as SLE, is challenging. Improved recruitment strategies are needed for identifying patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Electronic health record algorithms were developed and tested to identify children with SLE both with and without lupus nephritis. We used single-center electronic health record data to develop computable phenotypes composed of diagnosis, medication, procedure, and utilization codes. These were evaluated iteratively against a manually assembled database of patients with SLE. The highest-performing phenotypes were then evaluated across institutions in PEDSnet, a national health care systems network of >6.7 million children. Reviewers blinded to case status used standardized forms to review random samples of cases (n=350) and noncases (n=350). RESULTS: Final algorithms consisted of both utilization and diagnostic criteria. For both, utilization criteria included two or more in-person visits with nephrology or rheumatology and ≥60 days follow-up. SLE diagnostic criteria included absence of neonatal lupus, one or more hydroxychloroquine exposures, and either three or more qualifying diagnosis codes separated by ≥30 days or one or more diagnosis codes and one or more kidney biopsy procedure codes. Sensitivity was 100% (95% confidence interval [95% CI], 99 to 100), specificity was 92% (95% CI, 88 to 94), positive predictive value was 91% (95% CI, 87 to 94), and negative predictive value was 100% (95% CI, 99 to 100). Lupus nephritis diagnostic criteria included either three or more qualifying lupus nephritis diagnosis codes (or SLE codes on the same day as glomerular/kidney codes) separated by ≥30 days or one or more SLE diagnosis codes and one or more kidney biopsy procedure codes. Sensitivity was 90% (95% CI, 85 to 94), specificity was 93% (95% CI, 89 to 97), positive predictive value was 94% (95% CI, 89 to 97), and negative predictive value was 90% (95% CI, 84 to 94). Algorithms identified 1508 children with SLE at PEDSnet institutions (537 with lupus nephritis), 809 of whom were seen in the past 12 months. CONCLUSIONS: Electronic health record-based algorithms for SLE and lupus nephritis demonstrated excellent classification accuracy across PEDSnet institutions.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Giant Cell Arteritis and Takayasu Arteritis.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of giant cell arteritis (GCA) and Takayasu arteritis (TAK) as exemplars of large vessel vasculitis. METHODS: Clinical questions regarding diagnostic testing, treatment, and management were developed in the population, intervention, comparator, and outcome (PICO) format for GCA and TAK (27 for GCA, 27 for TAK). Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to rate the quality of the evidence. Recommendations were developed by the Voting Panel, comprising adult and pediatric rheumatologists and patients. Each recommendation required ≥70% consensus among the Voting Panel. RESULTS: We present 22 recommendations and 2 ungraded position statements for GCA, and 20 recommendations and 1 ungraded position statement for TAK. These recommendations and statements address clinical questions relating to the use of diagnostic testing, including imaging, treatments, and surgical interventions in GCA and TAK. Recommendations for GCA include support for the use of glucocorticoid-sparing immunosuppressive agents and the use of imaging to identify large vessel involvement. Recommendations for TAK include the use of nonglucocorticoid immunosuppressive agents with glucocorticoids as initial therapy. There were only 2 strong recommendations; the remaining recommendations were conditional due to the low quality of evidence available for most PICO questions. CONCLUSION: These recommendations provide guidance regarding the evaluation and management of patients with GCA and TAK, including diagnostic strategies, use of pharmacologic agents, and surgical interventions.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of antineutrophil cytoplasmic antibody-associated vasculitis (AAV), including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). METHODS: Clinical questions regarding the treatment and management of AAV were developed in the population, intervention, comparator, and outcome (PICO) format (47 for GPA/MPA, 34 for EGPA). Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the quality of evidence and formulate recommendations. Each recommendation required ≥70% consensus among the Voting Panel. RESULTS: We present 26 recommendations and 5 ungraded position statements for GPA/MPA, and 15 recommendations and 5 ungraded position statements for EGPA. This guideline provides recommendations for remission induction and maintenance therapy as well as adjunctive treatment strategies in GPA, MPA, and EGPA. These recommendations include the use of rituximab for remission induction and maintenance in severe GPA and MPA and the use of mepolizumab in nonsevere EGPA. All recommendations are conditional due in part to the lack of multiple randomized controlled trials and/or low-quality evidence supporting the recommendations. CONCLUSION: This guideline presents the first recommendations endorsed by the American College of Rheumatology and the Vasculitis Foundation for the management of AAV and provides guidance to health care professionals on how to treat these diseases.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Polyarteritis Nodosa.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of systemic polyarteritis nodosa (PAN). METHODS: Twenty-one clinical questions regarding diagnostic testing, treatment, and management were developed in the population, intervention, comparator, and outcome (PICO) format for systemic, non-hepatitis B-related PAN. Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the quality of evidence and formulate recommendations. Each recommendation required ≥70% consensus among the Voting Panel. RESULTS: We present 16 recommendations and 1 ungraded position statement for PAN. Most recommendations were graded as conditional due to the paucity of evidence. These recommendations support early treatment of severe PAN with cyclophosphamide and glucocorticoids, limiting toxicity through minimizing long-term exposure to both treatments, and the use of imaging and tissue biopsy for disease diagnosis. These recommendations endorse minimizing risk to the patient by using established therapy at disease onset and identify new areas where adjunctive therapy may be warranted. CONCLUSION: These recommendations provide guidance regarding diagnostic strategies, use of pharmacologic agents, and imaging for patients with PAN.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Giant Cell Arteritis and Takayasu Arteritis.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of giant cell arteritis (GCA) and Takayasu arteritis (TAK) as exemplars of large vessel vasculitis. METHODS: Clinical questions regarding diagnostic testing, treatment, and management were developed in the population, intervention, comparator, and outcome (PICO) format for GCA and TAK (27 for GCA, 27 for TAK). Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to rate the quality of the evidence. Recommendations were developed by the Voting Panel, comprising adult and pediatric rheumatologists and patients. Each recommendation required ≥70% consensus among the Voting Panel. RESULTS: We present 22 recommendations and 2 ungraded position statements for GCA, and 20 recommendations and 1 ungraded position statement for TAK. These recommendations and statements address clinical questions relating to the use of diagnostic testing, including imaging, treatments, and surgical interventions in GCA and TAK. Recommendations for GCA include support for the use of glucocorticoid-sparing immunosuppressive agents and the use of imaging to identify large vessel involvement. Recommendations for TAK include the use of nonglucocorticoid immunosuppressive agents with glucocorticoids as initial therapy. There were only 2 strong recommendations; the remaining recommendations were conditional due to the low quality of evidence available for most PICO questions. CONCLUSION: These recommendations provide guidance regarding the evaluation and management of patients with GCA and TAK, including diagnostic strategies, use of pharmacologic agents, and surgical interventions.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Polyarteritis Nodosa.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of systemic polyarteritis nodosa (PAN). METHODS: Twenty-one clinical questions regarding diagnostic testing, treatment, and management were developed in the population, intervention, comparator, and outcome (PICO) format for systemic, non-hepatitis B-related PAN. Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the quality of evidence and formulate recommendations. Each recommendation required ≥70% consensus among the Voting Panel. RESULTS: We present 16 recommendations and 1 ungraded position statement for PAN. Most recommendations were graded as conditional due to the paucity of evidence. These recommendations support early treatment of severe PAN with cyclophosphamide and glucocorticoids, limiting toxicity through minimizing long-term exposure to both treatments, and the use of imaging and tissue biopsy for disease diagnosis. These recommendations endorse minimizing risk to the patient by using established therapy at disease onset and identify new areas where adjunctive therapy may be warranted. CONCLUSION: These recommendations provide guidance regarding diagnostic strategies, use of pharmacologic agents, and imaging for patients with PAN.

2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

OBJECTIVE: To provide evidence-based recommendations and expert guidance for the management of antineutrophil cytoplasmic antibody-associated vasculitis (AAV), including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). METHODS: Clinical questions regarding the treatment and management of AAV were developed in the population, intervention, comparator, and outcome (PICO) format (47 for GPA/MPA, 34 for EGPA). Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the quality of evidence and formulate recommendations. Each recommendation required ≥70% consensus among the Voting Panel. RESULTS: We present 26 recommendations and 5 ungraded position statements for GPA/MPA, and 15 recommendations and 5 ungraded position statements for EGPA. This guideline provides recommendations for remission induction and maintenance therapy as well as adjunctive treatment strategies in GPA, MPA, and EGPA. These recommendations include the use of rituximab for remission induction and maintenance in severe GPA and MPA and the use of mepolizumab in nonsevere EGPA. All recommendations are conditional due in part to the lack of multiple randomized controlled trials and/or low-quality evidence supporting the recommendations. CONCLUSION: This guideline presents the first recommendations endorsed by the American College of Rheumatology and the Vasculitis Foundation for the management of AAV and provides guidance to health care professionals on how to treat these diseases.

Multisystem Inflammatory Syndrome of Children: Subphenotypes, Risk Factors, Biomarkers, Cytokine Profiles, and Viral Sequencing.

OBJECTIVE: To assess demographic, clinical, and biomarker features distinguishing patients with multisystem inflammatory syndrome in children (MIS-C); compare MIS-C sub-phenotypes; identify cytokine biosignatures; and characterize viral genome sequences. STUDY DESIGN: We performed a prospective observational cohort study of 124 children hospitalized and treated under the institutional MIS-C Task Force protocol from March to September 2020 at Children's National, a quaternary freestanding children's hospital in Washington, DC. Of this cohort, 63 of the patients had the diagnosis of MIS-C (39 confirmed, 24 probable) and 61 were from the same cohort of admitted patients who subsequently had an alternative diagnosis (controls). RESULTS: Median age and sex were similar between MIS-C and controls. Black (46%) and Latino (35%) children were over-represented in the MIS-C cohort, with Black children at greatest risk (OR 4.62, 95% CI 1.151-14.10; P = .007). Cardiac complications were more frequent in critically ill patients with MIS-C (55% vs 28%; P = .04) including systolic myocardial dysfunction (39% vs 3%; P = .001) and valvular regurgitation (33% vs 7%; P = .01). Median cycle threshold was 31.8 (27.95-35.1 IQR) in MIS-C cases, significantly greater (indicating lower viral load) than in primary severe acute respiratory syndrome coronavirus 2 infection. Cytokines soluble interleukin 2 receptor, interleukin [IL]-10, and IL-6 were greater in patients with MIS-C compared with controls. Cytokine analysis revealed subphenotype differences between critically ill vs noncritically ill (IL-2, soluble interleukin 2 receptor, IL-10, IL-6); polymerase chain reaction positive vs negative (tumor necrosis factor-α, IL-10, IL-6); and presence vs absence of cardiac abnormalities (IL-17). Phylogenetic analysis of viral genome sequences revealed predominance of GH clade originating in Europe, with no differences comparing patients with MIS-C with patients with primary coronavirus disease 19. Treatment was well tolerated, and no children died. CONCLUSIONS: This study establishes a well-characterized large cohort of MIS-C evaluated and treated following a standardized protocol and identifies key clinical, biomarker, cytokine, viral load, and sequencing features. Long-term follow-up will provide opportunity for future insights into MIS-C and its sequelae.