Juvenile Idiopathic Inflammatory Myopathy and Juvenile Dermatomyositis: Characteristics and outcomes of affected children at a Paediatric Rheumatology Clinic in a tropical climate.

Abstract

Background Juvenile Idiopathic Inflammatory Myopathy (JIIM) is a rare autoimmune condition of which Juvenile Dermatomyositis (JDM) is the most common subtype. To this date there has been no published data focusing on this condition in Trinidad nor the English-speaking Caribbean. Methods A retrospective folder analysis was done on patients with JIIM who attended the recently formed Paediatric Rheumatology Multi-Disciplinary Clinic over a 6 months period from May 2021 at San Fernando Teaching Hospital, Trinidad and Tobago. Demographics, investigations and diagnoses were analysed. A secondary comparative analysis of two diagnostic criteria was performed and treatment approach was examined. Results 5 notes were reviewed in this period. The male: female ratio was 1:4 and the average age of onset was 6.8 years. 80% of JIIM cases were JDM. The most common presenting complaints were: skin rash and weakness (62%). The most common additional symptoms were: joint pain (60%) and pruritis (60%). Previous upper respiratory tract infection was recognized in 40% of JIIM patients and one patient had Kawasaki disease 6 years prior. Creatine Kinase showed modest elevations in JDM, whilst it was extremely elevated in one patient with myositis. There was an 80% concordance between the EULAR/ACR 2017 and the Peter and Bohan 1975 criteria. 60% tested positive for ANA. Anti PM, Anti Ku, Anti RP155, Anti Mi2A, Anti Mi2B and Anti RP11 antibodies were identified. 40% were positive for AntiRP155. 60% of patients utilized MRI imaging which detected myositis in all reports. Methotrexate and prednisolone were used in 100%. Parenteral drugs used included: intravenous immunoglobulin and methylprednisolone. 80% had vitamin D supplementation and 100% were prescribed physiotherapy. One child had intractable calcinosis. Conclusions Whilst the study size was arguably small, patterns were seen which are in keeping with international data on epidemiology and treatment. Recommendations from this study include: greater utilization of MRI in diagnostic workup, further evaluating anti RP155 antibody as a new myositis associated antibody in a Caribbean population and exploring further options for calcinosis treatment in a developing nation.