Session Type: Poster Session (Monday)
Session Time: 9:00AM-11:00AM
Background/Purpose: Inflammatory myopathies (IM) are a heterogeneous group of diseases characterized by muscle inflammation. In Argentina, there are few pathologists specialized in muscle biopsies and for this reason, there are limitations to perform good quality biopsies.
The objectives of this study are to estimate the frequency of muscle biopsy in patients with IM belonging to Argentinean Society of Rheumatology database, identify the variables associated with its performance and to apply the new EULAR-ACR criteria to the subgroup of patients with biopsy.
Methods: 179 patients with IM were included. Demographic, clinical, laboratory, images and treatment characteristics were collected from medical records.
The muscle biopsy information was obtained from the pathology report of each participating hospital. Therefore, there was no standardization in the report.
To analyze differences between the groups, Chi square was performed for categorical variables and T test or Mann Whitney for continuous variables according to their distribution. Logistic regression analysis was performed for the analysis of variables associated with performing a muscle biopsy.
Results: Table 1 describes clinical characteristics of the cohort. The frequency of muscle biopsies in the cohort was 58 (32%). Table 2 shows variables associated to not having muscle biopsy performed.
In the logistic regression analysis, the presence of positive antibodies OR 0.21 (CI 95% 0.05- 0.99) and heliotrope rash 0.11 (CI 95% 0.02 to 0.75) were independently associated with NOT performing biopsy.
The complete biopsy report was available in 37 of 52 patients who undergone biopsy. In those patients we applied the EULAR-ACR criteria for inflammatory myopathies with and without biopsy(1).
Conclusion: Muscle biopsy was performed in only one third of patients with IM from our cohort. Patients with myositis-specific antibodies and heliotrope rash were biopsied less frequently. If criteria without biopsy are applied to patients with biopsy most of them will fulfill criteria. Given the difficulties to obtain a good quality muscle biopsy, we propose to only perform muscle biopsy to those patients who do not fulfill non biopsy EULAR-ACR criteria.
- Lundberg IE, Tjärnlund A, Bottai M, Werth VP, Pilkington C, Visser M De, et al. 2017 European League Against Rheumatism / American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis. 2017;69(12):2271–82.
To cite this abstract in AMA style:Virasoro B, Gomez R, Braillard Poccard A, Capelusnik D, Schneeberger E, Papasidero S, Bande J, Viola M, de la Vega M, Costi C, Garcia M, Asnal C, Cappuccio A, Yucra D, Vergel Orduz L, Tamborenea N, Rivero M, Granel A, Segura Escobar C, Dalpiaz M, Pisoni C. Idiopathic Inflammatory Myopathies: Are Muscle Biopsies Still Needed? [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/idiopathic-inflammatory-myopathies-are-muscle-biopsies-still-needed/. Accessed September 24, 2021.
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