AB0573 IDIOPATHIC INFLAMMATORY MYOPATHIES: A SINGLE-CENTER EXPERIENCE
Authors: B. H. Egeli, S. Ergun, A. Cetin, Y. K. Gursoy, S. Ugurlu
Journal: Annals of the Rheumatic Diseases (2020)

Background: Idiopathic inflammatory myopathies (IIM), mainly dermatomyositis (DM) and polymyositis (PM) are the diseases of the musculoskeletal system most commonly affecting the proximal muscles of the limbs. In addition to muscle inflammation, these conditions are multisystemic, presenting with a variety of complaints. Objectives: As IIMs are infrequent, a single-center experience presenting quantitative data describing in-depth information on the nature of disease and treatment seems useful. Methods: This retrospective study was conducted at a tertiary rheumatology center. Patients were diagnosed with an idiopathic inflammatory myopathy (DM, PM) in order to be included in this study. Clinical signs and symptoms of the presentation were noted during the first patient encounter as well as the follow-up. Parameters of disease activity including acute phase reactants, muscle enzyme levels, and disease-specific autoantibodies were analyzed. Treatment and prognosis information was also noted with additional information from phone call interviews. Results: The study includes 108 patients (78 DM, 30 PM). The mean age of diagnosis was 43.17 ±18.73 years, follow-up duration was 44.37 ±60.58 months. The presenting signs and symptoms of the patients are shown in Figure 1. The parameters of disease activity before and after treatment are summarized in Table 1. The clinical tests ordered during the disease management are summarized in Table 2. The mean corticosteroid dose decreased from 45.65 ±114.53 mg to 15.22 ±16.77 (p=0.007). Other treatment methods were methotrexate (n=72), rituximab (n=28), Intravenous Immunoglobulin (IVIG) (n=9), and cyclophosphamide (n=5). Ten patients died during the follow-up. Thirty-six patients were lost to follow-up. Table 1. The Parameters of Disease Activity Before and After Treatment Before Treatment After Treatment P Value CPK, mean ± std (U/L ) 2429.55 ± 5503.85 210.23 ± 352.97 &lt;0.0001 LDH, mean ± std (U/L ) 659.48 ± 458.74 262.83 ± 139.81 &lt;0.0001 AST, mean ± std (U/L ) 82.22 ± 92.63 25.94 ± 18.76 &lt;0.0001 ALT, mean ± std (U/L ) 75.28 ± 83.3 26.48 ± 21.68 &lt;0.0001 ESR, mean ± std (mm/hour ) 28.7 ± 25.36 25.62 ± 22.53 0.35 CRP, mean ± std (mg/L ) 14.76 ± 26.86 9.12 ± 18.23 0.07 RF, mean ± std (U/mL ) 15.72 ± 19.96 N/A N/A ANA, n (% ) 26 (24.07) N/A N/A Anti- JO 1, n(% ) 5 (4.63) N/A N/A Table 2. The Clinical Tests Ordered during the Disease Management Tested Positive Muscle Biopsy, n(% ) 28 (25.93) 23 (82.14) Skin Biopsy, n(% ) 9 (8.33) 9 (100) Thorax CT, n(% ) 24 (22.22 18 (75) Abdominal CT, n(% ) 11 (10.19) 8 (72.73) EMG, n(% ) 43 (39.81) 36 (83.72) Figure 1. The Presenting Signs and Symptoms of the Patients Conclusion: IIMs are very rare and can present with very different signs and symptoms. Referral to rheumatology can be challenging along with treatment. With inadequate clinical insight diagnosis and management of these patients can be delayed and quite expensive. Long term follow-up in our center enabled adequate control of disease activity as proven by the highly significant decrease in parameters of disease activity, especially muscle enzyme levels. Furthermore, we reported the variety of clinical symptoms, investigation methods and treatment essays in our center trying to reflect the potential challenges that can hinder a health clinical practice as well as highlight the requirement of a standardized approach. Disclosure of Interests: None declared