POS1296 RENAL AND MUSCULOSKELETAL COMPLICATIONS IN MYOPATHY: A COMPREHENSIVE COHORT STUDY COMPARING NON-INFLAMMATORY RHABDOMYOLYSIS TO INFLAMMATORY MYOPATHIES
Authors: R. Ali, A. K. Palmer, Y. González Moret, S. Abdollahi, A. Lau, F. Rodriguez, I. Tan
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Rhabdomyolysis, characterized by muscle necrosis, is associated with kidney injury. This is reported in 15 to over 50 percent of cases. Various factors, including trauma, immobilization, strenuous exercise, metabolic issues, toxins, medications, and infections, can contribute to rhabdomyolysis. Inflammatory myopathy is a rare cause of rhabdomyolysis and is reported to be associated with kidney injury. The musculoskeletal complication of rhabdomyolysis includes compartment syndrome, which can result from severe rhabdomyolysis and may develop after fluid resuscitation. Compartment syndrome can also be a cause of rhabdomyolysis, especially in traumatic cases. <h3>Objectives:</h3> This observational, retrospective cohort study examines the frequency of renal complications (acute kidney injury AKI and chronic kidney disease CKD) and the occurrence of compartment syndrome in patients with rhabdomyolysis with noninflammatory causes compared to patients with inflammatory myositis on a large scale. We utilized the TrinetX database, which encompasses electronic health care records from approximately 80 different global healthcare organizations. <h3>Methods:</h3> Two cohorts were established using the TriNetX database. Cohort 1 included patients with rhabdomyolysis (excluding cases of inflammatory myopathy), and Cohort 2 included cases with inflammatory myopathy (we studied polymyositis PM, dermatomyositis DM, and inclusion body myositis IBM) using the International Classification of Diseases, Tenth Revision (ICD-10) codes. Immune mediated necrotizing myopathy cases were not included given lack of specific ICD-10 code. We included patients aged 18 years and above in both groups. The index event was the initial appearance of rhabdomyolysis and inflammatory myopathy diagnosis. Propensity score matching was employed for age and race/ethnicity, as well as various comorbidities (including hypertension, hyperlipidemia, diabetes mellitus, and coronary artery disease). Our outcomes of interest included AKI, CKD, and compartment syndrome within 6 months of the index events. We excluded patients who had outcomes prior to the index events. We used measures of association to calculate the risk and risk ratio. <h3>Results:</h3> The analysis involved 195,272 patients with non-inflammatory causes of rhabdomyolysis (cohort 1) and 47,009 patients with inflammatory myopathies (cohort 2). The average age at the time of index events was approximately 55 years in both cohorts. Cohort 1 exhibited a male predominance, whereas cohort 2 consisted mainly of females. There was no significant difference in racial distribution, with a slight predominance of the white population in both cohorts. After propensity score matching, 38,198 patients from each group were included in the analysis. Within 6 months of the index event, 5.597% of cohort 1 (compared to 1.604% of cohort 2) developed AKI, with a risk difference of 3.993% and a risk ratio of 3.489 (95% CI: 3.168-3.844; P &lt; 0.0001). Regarding CKD, 3.286% of cohort 1 and 1.422% of cohort 2 developed the outcome within 6 years of the index event, with a risk difference of 1.864%, and a risk ratio of 2.311 (95% CI 2.083, 2.565; P &lt; 0.0001), higher in cohort 1. Rhabdomyolysis of non-inflammatory causes was associated with a higher incidence of compartment syndrome compared to inflammatory myopathy, with a risk ratio of 12.433 (95% CI 6.526, 23.687; P &lt; 0.0001). <h3>Conclusion:</h3> The findings of this study revealed a statistically significant increase in the risk of renal and musculoskeletal complications (AKI, CKD and compartment syndrome) in patients with rhabdomyolysis attributed to non-inflammatory causes when compared to those with inflammatory myopathy (PM, DM and IBM). <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>