Background This study aimed to assess the baseline characteristics and clinical outcomes of coronavirus disease 2019 (COVID-19) in pediatric patients with rheumatic and musculoskeletal diseases (RMD) and identify the risk factors associated with symptomatic or severe disease defined as hospital admission, intensive care admission or death. Methods An observational longitudinal study was conducted during the first year of the SARS-CoV-2 pandemic (March 2020–March 2021). All pediatric patients attended at the rheumatology outpatient clinics of six tertiary referral hospitals in Madrid, Spain, with a diagnosis of RMD and COVID-19 were included. Main outcomes were symptomatic disease and hospital admission. The covariates were sociodemographic and clinical characteristics and treatment regimens. We ran a multivariable logistic regression model to assess associated factors for outcomes. Results The study population included 77 pediatric patients. Mean age was 11.88 (4.04) years Of these, 30 patients (38.96%) were asymptomatic, 41 (53.25%) had a mild-moderate COVID-19 and 6 patients (7.79%) required hospital admission. The median length of hospital admission was 5 (2–20) days, one patient required intensive care and there were no deaths. Previous comorbidities increased the risk for symptomatic disease and hospital admission. Compared with outpatients, the factor independently associated with hospital admission was previous use of glucocorticoids (OR 3.51; p = 0.00). No statistically significant risk factors for symptomatic COVID-19 were found in the final model. Conclusion No differences in COVID-19 outcomes according to childhood-onset rheumatic disease types were found. Results suggest that associated comorbidities and treatment with glucocorticoids increase the risk of hospital admission.

Background Primary pyomyositis is a rare condition in children that should be included in the differential diagnosis of musculoskeletal infections. Objectives To describe the clinical features of pyomyositis as well as its diagnostic and therapeutic approach. Methods A descriptive and retrospective study was performed by reviewing medical records of patients admitted to our hospital from January 1996 to July 2013 with a diagnosis of primary pyomyositis. Results A total of 25 patients (16 men, 9 women) aged between one month and 14 years (median age 2 years) were registered. Two peaks of incidence have been found in the months of July and October. The most frequent clinical manifestations were the presence of local pain (24 patients), fever (18 patients), local swelling (9 patients) and skin rash (7 patients). Predisposing factors in 8 patients (1 strenuous exercise, 4 trauma, 3 intramuscular injections) were found. The primary site was pelvic muscles or lower extremities (20 patients). In laboratory results, we found the presence of leukocytosis, with an average value of 12,936±5.753/uL leukocytes, total neutrophils 4.659/uL ±7.350), ESR of 55±28 mm) and PCR 8±6 mg/dL). CPK was normal in 5 out of 6 patients who were requested. Laboratory results were positive for Staphylococcus aureus (7 patients), Salmonella no tiphy (1 patient) and Bacteroides fragillis (1 patient). Ultrasound suggested the diagnosis in 11 cases and magnetic resonance imaging support the diagnosis in all cases. All patients received intravenous antibiotic therapy (mean duration 11 days) followed by oral antibiotic therapy (mean duration 23 days). 9 patients suffered complications as abscess formation, 3 need abscess aspiration and one of them required surgical drainage. None of our patients had residual functional limitations. Conclusions It is important to have a high index of suspicion for pyomyositis in patients with fever and musculoskeletal pain at an early stage in order to initiate start appropriate antibiotic treatment against Staphylococcus aureus. Although ESR and ultrasound may be useful, it is necessary to complement with magnetic resonance imaging in order to support the diagnosis in all cases. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.4467

Alendronate (ALN) and other bisphosphonates have been used successfully in pediatric patients with osteopenia secondary to connective tissue diseases. Loss of growth in height has not been reported, but concerns remain regarding the effect of these potent antiresorptive agents when used in children and adolescents. High-dose methotrexate (MTX) and other chemotherapy drugs have been implicated in osteoporosis and a high fracture incidence in survivors of childhood cancers and are also associated with osteopenia in adult animals. The effect of high dose MTX on bone density during rapid skeletal growth, however, has not been widely studied, nor has the potentially therapeutic effect of bisphosphonates in this setting. We examined the effects of ALN and MTX administration, alone and in combination, on bone density, morphology, mechanical strength, and longitudinal growth in normal growing rats. Sprague-Dawley rats were given ALN once weekly (0.3 mg/kg) from 5 to 11 weeks of age, with and without a course of methotrexate (MTX) given daily in weeks 1 and 3 (0.75 mg/kg/day). Twenty-four animals were randomly divided into four groups: Control (vehicle), ALN alone, ALN þ MTX, and MTX alone. After 6 weeks, the femora, tibiae, and lumbar spine were studied by dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, mechanical strength testing, microradiography, light microscopy, and by determination of ash weights and bone lengths. ALN treatment increased bone mineral density (BMD) by 23% to 68%. The largest increases in the femur occurred in the distal third where endochondral bone growth was greatest and included large increases in trabecular bone and total cross-sectional area. ALN þ MTX produced similar effects to ALN alone. MTX only reduced BMD by 8% in the vertebrae, but not significantly at other sites. MTX also led to femoral length reductions of 2.9%. The small reductions in BMD due to MTX were overwhelmed by the increases due to ALN, whereas the length loss was unaffected. Transverse density banding corresponding to weekly ALN administrations were clearly evident radiographically throughout the growing skeleton, likely due to decreased resorption and possibly increased mineralization in the bands. ALN or ALN þ MTX treatment also led to increases in mechanical strength in the femora. Although MTX administration during growth leads to some BMD reduction, ALN given with MTX eliminates this reduction and in fact bone density and strength increase above control levels. ß

BackgroundDeficiency of the interleukin (IL)−36 receptor antagonist (DITRA) is an autosomal recessive autoinflammatory syndrome caused by mutations in the IL36RN gene. Clinical manifestations of DITRA include recurrent episodes of generalised skin postulation, fever, systemic inflammation and leukocytosis. An uniformly effective treatment for DITRA has not yet been identified.ObjectivesWe present a case of a 5 year old patient with DITRA with prolonged response with tumour necrosis factor alfa inhibition with adalimumab.MethodsA five-year-old came to our dermatology clinic after worsening of a previous diagnosed plaque psoriasis, with an erythematous scaly dermatitis that extended throughout the trunk. Treatment with acitretin and cyclosporin were not effective and patient developed in few weeks a generalised erythroderma with pustules covering almost every part of his body, including palms and soles. He was admitted for the onset of fever and irritability due to painful rubbing of the skin. Family history of recurrent fevers or psoriasis were not revealed. Parents were not consanguineous.Complete blood count showed leukocytosis with neutrophilia and thrombocytosis, with an erythrocyte sedimentation rate (ESR) of 6 mm/hr and a C-reactive protein (CRP) of 8,4 mg/dl. Biochemistry panel revealed a mild elevation of liver enzymes without other abnormalities. Antinuclear antibody (ANA) and rheumatoid factor were negative with normal serum immunoglobulin and complement. Blood culture grew E. Coli, S. Maltophila and S. epidermidis. Skin biopsy showed acanthosis and papillomatosis with perivascular polymorphous inflammatory cells. Genetic analyses showed a homozygous mutation in the IL36RN gene (pSer113Leu). No mutations were detected in IL1RN and CARD 14 genes.ResultsTreatment was initiated with intravenous methylprednisolone 2 mg/kg/day and subcutaneous anakinra 2 mg/kg/day. Cefotaxime and co-trimoxazole were added until blood cultures were negative. Although skins lesions improved during the following days and patient was finally discharged, symptoms reappeared when decreasing the steroid dose. Three months later adalimumab and methotrexate were started, allowing the patient to end treatment with corticoids without evidence of activity of the disease.Abstract AB1087 – Figure 1ConclusionsAfter incomplete response with anakinra, inhibition of tumour necrosis factor alfa resulted in a prolonged response in our patient with deficiency of the interleukin (IL)−36 receptor antagonist (DITRA).Disclosure of InterestNone declared

OBJECTIVES To evaluate risk factors for severe Coronavirus Disease 2019 (COVID-19) in patients with immune-mediated rheumatic diseases, stratified by systemic autoimmune conditions and chronic inflammatory arthritis. METHODS An observational, cross-sectional multicenter study was performed. Patients from 10 Rheumatology departments in Madrid who presented with SARS-CoV-2 infection between Feb 2020 and May 2021 were included. The main outcome was COVID-19 severity (hospital admission or mortality). Risk factors for severity were estimated, adjusting for covariates (sociodemographic, clinical and treatments), using logistic regression analyses. RESULTS 523 patients with COVID-19 were included, among whom 192 (35.6%) patients required hospital admission and 38 (7.3%) died. Male gender, older age and comorbidities such as diabetes mellitus, hypertension and obesity were associated with severe COVID-19. Corticosteroid doses over 10 mg/day, rituximab, sulfasalazine and mycophenolate use, were independently associated with worse outcomes. COVID-19 severity decreased over the different pandemic waves. Mortality was higher in the systemic autoimmune conditions (univariate analysis, p<0.001), although there were no differences in overall severity in the multivariate analysis. CONCLUSIONS This study confirms and provides new insights regarding the harmful effects of corticosteroids, rituximab and other therapies (mycophenolate and sulfasalazine) in COVID-19. Methotrexate and anti-TNF therapy were not associated with worse outcomes.