COVID-19 infection in children and adolescents

The COVID-19 pandemic has predominantly affected the adult population. The disease is less well-defined in children (≤18 years). This review summarises the current understanding of the epidemiology, clinical manifestations, and management of COVID-19 in children and adolescents. The prevalence of COVID-19 is significantly lower in children than adults, but paediatric disease is likely underdiagnosed as a result of the high numbers of asymptomatic or mild cases. Children are vulnerable to family cluster outbreaks, but are unlikely to be index cases within a household. Vertical transmission or breast milk transmission are yet to be proven. Between 10 and 90% of paediatric COVID-19 cases are asymptomatic. Symptomatic cases typically present with mild symptoms, including cough, fever and sore throat. Intensive care admission and mortality are rare. Paediatric multisystem inflammatory syndrome temporally associated with COVID-19 is a rare, but severe, newly emerging phenotype. At present, there is no specific treatment for COVID-19 in adults or children; management is usually supportive. For severe or critical disease, including paediatric multisystem inflammatory syndrome temporally associated with COVID-19, the decision to start antiviral or immunomodulatory therapy should be on a case-by-case basis; in the UK, this should be done within a clinical trial. Further research is needed into both the disease course and treatment of paediatric COVID-19

Growth of a transplantable lymphoma and its modification in mice infected with the inducing virus.

The growth of a transplantable lymphoma was examined in normal mice and in mice previously infected with the lymphoma-inducing virus (ULV). Normal BALB/c mice respond to a footpad injection of X-irradiated lymphoma cells (ULMC) with popliteal lymph node (PLN) enlargement; mice previously infected with ULV do not. 106 viable ULMC injected into the footpads of ULV-infected mice grew progressively, and the animals died with disseminating malignant lymphoma. In contrast, this dose of cells injected into normal animals evoked strong host responses in the foot and draining lymph node, and no progressive growth of the lymphoma occurred. This increased susceptibility of the ULV-infected animals was also observed when ULMC were injected s.c. into the back or i.m. into the calf muscle, but not after s.c. injection of an unrelated 3-methylcholanthrene-induced sarcoma. Resistance to tumour growth after i.v. injection of ULMC is clearly ineffective, since 10 cells can grow and kill the animal, and in this case no increased susceptibility of ULV-infected animals was observed

Biomarkers of response to biologic therapy in juvenile idiopathic arthritis

Background: Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthritis of childhood, characterised by various clinical phenotypes associated with variable prognosis. Significant progress has been achieved with the use of biologic treatments, which specifically block pro-inflammatory molecules involved in the disease pathogenesis. The most commonly used biologics in JIA are monoclonal antibodies and recombinant proteins targeting interleukins 1 and 6, and tumour necrosis factor α (TNF-α). Several biomarkers have been investigated in JIA. Aims: To assess the level of evidence available regarding the role of biomarkers in JIA related to guiding clinical and therapeutic decisions, providing disease prognostic information, facilitating disease activity monitoring and assessing biologic treatment response in JIA, as well as propose new strategies for biologic therapy-related biomarker use in JIA. Methods: We searched PubMed for relevant literature using predefined key words corresponding to several categories of biomarkers to assess their role in predicting and assessing biologic treatment response and clinical remission in JIA. Results: We reviewed serological, cellular, genetic, transcriptomic and imaging biomarkers, to identify candidates that are both well-established and widely used, as well as newly investigated in JIA on biologic therapy. We evaluated their role in management of JIA as well as identified the unmet needs for new biomarker discovery and better clinical applications. Conclusions: Although there are no ideal biomarkers in JIA, we identified serological biomarkers with potential clinical utility. We propose strategies of combining biomarkers of response to biologics in JIA, as well as routine implementation of clinically acceptable imaging biomarkers for improved disease assessment performance

A Bayesian semiparametric Markov regression model for juvenile dermatomyositis

Juvenile dermatomyositis (JDM) is a rare autoimmune disease that may lead to serious complications, even to death. We develop a 2-state Markov regression model in a Bayesian framework to characterise disease progression in JDM over time and gain a better understanding of the factors influencing disease risk. The transition probabilities between disease and remission state (and vice versa) are a function of time-homogeneous and time-varying covariates. These latter types of covariates are introduced in the model through a latent health state function, which describes patient-specific health over time and accounts for variability among patients. We assume a nonparametric prior based on the Dirichlet process to model the health state function and the baseline transition intensities between disease and remission state and vice versa. The Dirichlet process induces a clustering of the patients in homogeneous risk groups. To highlight clinical variables that most affect the transition probabilities, we perform variable selection using spike and slab prior distributions. Posterior inference is performed through Markov chain Monte Carlo methods. Data were made available from the UK JDM Cohort and Biomarker Study and Repository, hosted at the UCL Institute of Child Health

Juvenile Dermatomyositis: what comes next? Long-term outcomes in childhood myositis from a patient perspective

BACKGROUND: To describe long-term outcomes in JDM using patient questionnaires and link to longitudinal, prospectively collected data for each patient within the Juvenile Dermatomyositis Cohort and Biomarker Study, UK and Ireland (JDCBS) to determine outcome predictors.  METHODS: JDCBS participants aged ≥ 16y completed the SF36, HAQ and a questionnaire regarding current disease features, medications, education and employment. Data collected from the JDCBS included disease subtype, demographics, clinical and laboratory features. Intensity indices were calculated for physician VAS, modified skin DAS, CMAS and MMT8 by dividing area under the curve (AUC) from longitudinal score trajectories by duration of study follow-up (y). Relationships between questionnaire and JDCBS clinical / laboratory data were investigated fitting statistical models appropriate for cross sectional and longitudinal data. RESULTS: Of 190 questionnaires sent, 84 (44%) were returned. Average age of respondents was 20.6 years (SD 3.9), time since diagnosis was 12.4 years (SD 5.0), age at onset was 9.2 years (SD 4.3), female to male ratio 4.25:1. Forty-nine (59%) self-reported persistently active disease, 54 (65%) were still taking immunosuppressive medication. 14/32 at school/higher education reported myositis adversely affecting academic results. 18–24 year-olds were twice as likely to be unemployed compared the UK population (OR = 0.456, 95% CI 0.24, 0.84, p = 0.001). Participants ≥ 18 years were three times as likely to be living with a parent/guardian (OR = 3.39, p < 0.001). SF36 MCS and MMT8 intensity index scores were significantly correlated (ρ = 0.328, p = 0.007). CONCLUSIONS: After 12.4 years, questionnaire responders reported self-perceived high rates of persistently active disease and medication use, reduced rates of employment and were more likely to live with a parent/guardian. Perceived persistently active muscle disease appeared to affect quality of life in these patients and was the most significant contributor to long-term outcomes. Our findings highlight the importance of including the patient perspective in the assessment of long term outcomes, so that that we can start to target initial management strategies more effectively based on a combination of clinical and patient-reported data

Development of an internationally agreed minimal dataset for juvenile dermatomyositis (JDM) for clinical and research use

Background: Juvenile dermatomyositis (JDM) is a rare autoimmune inflammatory disorder associated with significant morbidity and mortality. International collaboration is necessary to better understand the pathogenesis of the disease, response to treatment and long-term outcome. To aid international collaboration, it is essential to have a core set of data that all researchers and clinicians collect in a standardised way for clinical purposes and for research. This should include demographic details, diagnostic data and measures of disease activity, investigations and treatment. Variables in existing clinical registries have been compared to produce a provisional data set for JDM. We now aim to develop this into a consensus-approved minimum core dataset, tested in a wider setting, with the objective of achieving international agreement. Methods/Design: A two-stage bespoke Delphi-process will engage the opinion of a large number of key stakeholders through Email distribution via established international paediatric rheumatology and myositis organisations. This, together with a formalised patient/parent participation process will help inform a consensus meeting of international experts that will utilise a nominal group technique (NGT). The resulting proposed minimal dataset will be tested for feasibility within existing database infrastructures. The developed minimal dataset will be sent to all internationally representative collaborators for final comment. The participants of the expert consensus group will be asked to draw together these comments, ratify and 'sign off' the final minimal dataset. Discussion: An internationally agreed minimal dataset has the potential to significantly enhance collaboration, allow effective communication between groups, provide a minimal standard of care and enable analysis of the largest possible number of JDM patients to provide a greater understanding of this disease. The final approved minimum core dataset could be rapidly incorporated into national and international collaborative efforts, including existing prospective databases, and be available for use in randomised controlled trials and for treatment/protocol comparisons in cohort studies

Validation of a score tool for measurement of histological severity in juvenile dermatomyositis and association with clinical severity of disease.

OBJECTIVES: To study muscle biopsy tissue from patients with juvenile dermatomyositis (JDM) in order to test the reliability of a score tool designed to quantify the severity of histological abnormalities when applied to biceps humeri in addition to quadriceps femoris. Additionally, to evaluate whether elements of the tool correlate with clinical measures of disease severity. METHODS: 55 patients with JDM with muscle biopsy tissue and clinical data available were included. Biopsy samples (33 quadriceps, 22 biceps) were prepared and stained using standardised protocols. A Latin square design was used by the International Juvenile Dermatomyositis Biopsy Consensus Group to score cases using our previously published score tool. Reliability was assessed by intraclass correlation coefficient (ICC) and scorer agreement (α) by assessing variation in scorers' ratings. Scores from the most reliable tool items correlated with clinical measures of disease activity at the time of biopsy. RESULTS: Inter- and intraobserver agreement was good or high for many tool items, including overall assessment of severity using a Visual Analogue Scale. The tool functioned equally well on biceps and quadriceps samples. A modified tool using the most reliable score items showed good correlation with measures of disease activity. CONCLUSIONS: The JDM biopsy score tool has high inter- and intraobserver agreement and can be used on both biceps and quadriceps muscle tissue. Importantly, the modified tool correlates well with clinical measures of disease activity. We propose that standardised assessment of muscle biopsy tissue should be considered in diagnostic investigation and clinical trials in JDM

Validity of a three-variable juvenile arthritis disease activity score in children with new-onset juvenile idiopathic arthritis

<p>Objectives To investigate the validity and feasibility of the Juvenile Arthritis Disease Activity Score (JADAS) in the routine clinical setting for all juvenile idiopathic arthritis (JIA) disease categories and explore whether exclusion of the erythrocyte sedimentation rate (ESR) from JADAS (the ‘JADAS3’) influences correlation with single markers of disease activity.</p> <p>Methods JADAS-71, JADAS-27 and JADAS-10 were determined at baseline for an inception cohort of children with JIA in the Childhood Arthritis Prospective Study. JADAS3-71, JADAS3-27 and JADAS3-10 were determined using an identical formula but with exclusion of ESR. Correlation of JADAS with JADAS3 and single measures of disease activity/severity were determined by category.</p> <p>Results Of 956 eligible children, sufficient data were available to calculate JADAS-71, JADAS-27 and JADAS-10 at baseline in 352 (37%) and JADAS3 in 551 (58%). The median (IQR) JADAS-71, JADAS-27 and JADAS-10 for all 352 children was 11 (5.9–18), 10.4 (5.7–17) and 11 (5.9–17.3), respectively. Median JADAS and JADAS3 varied significantly with the category (Kruskal–Wallis p=0.0001), with the highest values in children with polyarticular disease patterns. Correlation of JADAS and JADAS3 across all categories was excellent. Correlation of JADAS71 with single markers of disease activity/severity was good to moderate, with some variation across the categories. With the exception of ESR, correlation of JADAS3-71 was similar to correlation of JADAS-71 with the same indices.</p> <p>Conclusions This study is the first to apply JADAS to all categories of JIA in a routine clinical setting in the UK, adding further information about the feasibility and construct validity of JADAS. For the majority of categories, clinical applicability would be improved by exclusion of the ESR.</p&gt

Comparison of some Reduced Representation Approximations

In the field of numerical approximation, specialists considering highly complex problems have recently proposed various ways to simplify their underlying problems. In this field, depending on the problem they were tackling and the community that are at work, different approaches have been developed with some success and have even gained some maturity, the applications can now be applied to information analysis or for numerical simulation of PDE's. At this point, a crossed analysis and effort for understanding the similarities and the differences between these approaches that found their starting points in different backgrounds is of interest. It is the purpose of this paper to contribute to this effort by comparing some constructive reduced representations of complex functions. We present here in full details the Adaptive Cross Approximation (ACA) and the Empirical Interpolation Method (EIM) together with other approaches that enter in the same category