Skeletal Muscle Manifestations and Creatine Kinase in COVID-19.

Background and Purpose: Skeletal muscle symptoms and elevated creatine kinase (CK) levels have been consistently reported as part of the COVID-19 disease process. Previous studies have yet to show a consistent relationship between CK levels and skeletal muscle symptoms, disease severity, and death from COVID-19. The purpose of this study is to determine whether elevated CK is associated with a COVID-19 course requiring intubation, intensive care, and/or causing death. Secondary objectives: To determine if there is a relationship between elevated CK and (1) skeletal muscle symptoms/signs (2) complications of COVID-19 and (3) other diagnostic laboratory values. Methods: This is a retrospective, single center cohort study. Data were collected from March 13, 2020, to May 13, 2020. This study included 289 hospitalized patients with laboratory-confirmed SARS-CoV-2 and measured CK levels during admission. Results: Of 289 patients (mean age 68.5 [SD 13.8] years, 145 [50.2%] were men, 262 [90.7%] were African American) with COVID-19, 52 (18.0%) reported myalgia, 92 (31.8%) reported subjective weakness, and 132 (45.7%) had elevated CK levels (defined as greater than 220 U/L). Elevated CK was found to be associated with severity of disease, even when adjusting for inflammatory marker C-reactive protein (initial CK: OR 1.006 [95% CI: 1.002-1.011]; peak CK: OR 1.006 [95% CI: 1.002-1.01]; last CK: 1.009 [95% CI: 1.002-1.016]; q = .04). Creatine kinase was not found to be associated with skeletal muscle symptoms/signs or with other laboratory markers. Conclusions: Creatine kinase is of possible clinical significance and may be used as an additional data point in predicting the trajectory of the COVID-19 disease process.