Elicitation of expert prior opinion to design the BARJDM trial in juvenile dermatomyositis.

OBJECTIVES: To elicit and quantify expert opinion concerning the relative merits of two treatments for a rare inflammatory disease: Juvenile dermatomyositis (JDM). The formal expression of expert opinion reported in this paper will be used in a Bayesian analysis of a forthcoming randomised controlled trial known as BARJDM (baricitinib for juvenile dermatomyositis). METHODS: A Bayesian prior elicitation meeting was convened, following a previously described methodological template. Opinion was sought on the probability that a patient in the BARJDM trial would achieve clinically inactive disease, off glucocorticoids (GC) within a 12-month period with either methotrexate (standard of care); or baricitinib (a Janus kinase inhibitor, JAKi), with GC schedules identical in both arms of the trial. Experts' views were discussed and refined following presentation and further discussion of summated published data regarding efficacy of methotrexate or JAKi for JDM. RESULTS: Ten UK paediatric rheumatology consultants (including one adolescent paediatric rheumatologist) participated in the elicitation meeting. All had expertise in JDM, leading active National Health Service clinics for this disease. Consensus expert prior opinion was that the most likely probability of clinically inactive disease off GC within 12 months was 0.55 on baricitinib and 0.23 on methotrexate, with a greater degree of uncertainty for baricitinib. CONCLUSION: Experts currently think that baricitinib is superior to MTX for the treatment of JDM, although there is uncertainty around this. BARJDM will therefore integrate randomised trial data with this expert prior opinion to derive a posterior distribution for the relative efficacy of baricitinib compared with MTX.

The prescription and monitoring of conventional synthetic disease-modifying anti-rheumatic drugs: British Society for Rheumatology guideline scope.

This guideline will provide up-to-date, evidence-based recommendations on the safe use of non-biologic DMARDs, also called conventional synthetic DMARDs (csDMARD), across the full spectrum of autoimmune rheumatic diseases. The guideline will update the guideline published in 2017 and will be expanded to include people of all ages. Updated information on the monitoring of DMARDs and vaccinations will be included. The guideline will be developed using the methods and processes described in the British Society for Rheumatology's 'Creating clinical guidelines: our protocol', updated 2023.

Why is a paediatric respiratory specialist integral to the paediatric rheumatology clinic?

Systemic connective tissue diseases (CTDs) are characterised by the presence of autoantibodies and multiorgan involvement. Although CTDs are rare in children, they are associated with pulmonary complications, which have a high morbidity and mortality rate. The exact pathophysiology remains unclear. The pleuropulmonary complications in CTD are diverse in their manifestations and are often complex to diagnose and manage. The most common CTDs are discussed. These include juvenile systemic lupus erythematosus, juvenile dermatomyositis, juvenile systemic sclerosis, Sjögren's syndrome and mixed connective tissue disease. We describe the clinical features of the pleuropulmonary complications, focusing on their screening, diagnosis and monitoring. Treatment strategies are also discussed, highlighting the factors and interventions that influence the outcome of lung disease in CTD and pulmonary complications of treatment. Early detection and prompt treatment in a multidisciplinary team setting, including respiratory and rheumatology paediatricians and radiologists, is paramount in achieving the best possible outcomes for these patients.

Anti-HMGCR Autoantibodies in Juvenile Idiopathic Inflammatory Myopathies Identify a Rare but Clinically Important Subset of Patients.

OBJECTIVE: We aimed to establish the prevalence and clinical associations of anti-HMG-CoA-reductase (anti-HMGCR) in a large UK cohort with juvenile myositis. METHODS: There were 381 patients investigated for anti-HMGCR using ELISA. RESULTS: Anti-HMGCR autoantibodies were detected in 4 patients (1%). These children had no or minimal rash and significant muscle disease. Muscle biopsies were considered distinctive, with widespread variation in fiber size, necrotic fibers, and chronic inflammatory cell infiltrates; all had prolonged elevation of creatine kinase and all ultimately received biologic therapies. CONCLUSION: Anti-HMGCR in UK children with myositis are associated with severe disease that is poorly responsive to standard treatment.

Respiratory complications of the rheumatological diseases in childhood.

Pleuropulmonary manifestations of rheumatological diseases are rare in children but pose a significant risk to overall morbidity and mortality. We have reviewed the literature to provide an overview of the respiratory complications of the commonest rheumatological diseases to occur in children (juvenile systemic lupus erythematosus, scleroderma, juvenile dermatomyositis, mixed connective tissue disease, granulomatosis with polyangitis and juvenile idiopathic arthritis). Pulmonary function testing in these patients can be used to refine the differential diagnosis and establish disease severity, but also has a role in ongoing monitoring for respiratory complications. Early detection of pulmonary involvement allows for prompt and targeted therapies to achieve the best outcome for the child. This is best achieved with joint specialist paediatric rheumatology and respiratory reviews in a multidisciplinary setting.