It is the commonest of the idiopathic inflammatory myopathies of childhood,

comprising 85% of cases.[1, 2] It has an annual incidence estimated to range between 1.9 and 4.1 per million children.[3, 4] Clinically, JDM is characterized by muscle check details weakness and typical skin involvement. It may also involve multiple other systems, including the gastrointestinal tract, heart, lungs, kidneys and eyes. The diagnosis of JDM is based on criteria first proposed by Bohan and Peter in 1975.[5, 6] These criteria are: proximal muscle weakness, characteristic rash, raised muscle enzymes and typical electromyography (EMG) and muscle biopsy changes. In recent years magnetic resonance imaging (MRI) has played an increasingly important

role in the diagnosis of inflammatory muscle disease and in many situations has BMS-354825 chemical structure obviated the need for invasive procedures such as EMG and muscle biopsy.[7] Previous studies have described the clinical features and course of large JDM cohorts in North America, Europe, South America, Saudi Arabia and Japan. To our knowledge, there is only one other Australasian study that describes a cohort of patients with JDM.[8] The aim of this study was to describe the clinical features, complications, course and treatment of JDM at an Australian tertiary referral centre over the past two decades. A retrospective chart review was conducted of all patients diagnosed with JDM at the Royal Children’s Hospital (RCH) in Melbourne between 1989 and 2010. The study was approved by the RCH Human Research Ethics Committee. Patients were identified by 3-oxoacyl-(acyl-carrier-protein) reductase two search strategies. The first involved a search of the hospital medical records database to identify patients discharged from the hospital between January

1989 and June 2010 with an International Classification of Diseases 9th or 10th edition (ICD-9 or ICD-10) code potentially compatible with the diagnosis of JDM. The ICD-9 codes used were 710.3 (Dermatomyositis) and 710.4 (Polymyositis) and the ICD 10 codes used were M33.0 (Juvenile Dermatomyositis), M33.1 (Other Dermatomyositis), M33.2 (Polymyositis) and M33.9 (Dermatopolymyositis, unspecified). The second search method involved interrogation of the Rheumatology Department’s independent electronic database to search for patients assigned a diagnosis of JDM over the same period. The charts of all patients identified were reviewed by a single reviewer (PG) and information concerning patient demographics, treating team, clinical features at onset and throughout the course of the illness, investigation results, and therapy were entered into an electronic database. Patients were included in the study if they met the Bohan and Peter[6] criteria for definite, probable or possible JDM. Additionally, to be included patients had to have been managed at RCH throughout the course of their illness and have had at least 3 months of follow-up.