Muscle involvement in SARS‐CoV‐2 infection

BACKGROUND AND PURPOSE: Since the outbreak of the severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) pandemic, several reports indicated neurological involvement in COVID‐19 disease. Muscle involvement has also been reported as evidenced by creatine kinase (CK) elevations and reports of myalgia. METHODS: Creatine kinase, markers of inflammation, pre‐existing diseases and statin use were extracted from records of Austrian hospitalised COVID‐19 patients. Disease severity was classified as severe in case of intensive care unit (ICU) admission or mortality. COVID‐19 patients were additionally compared to an historical group of hospitalised influenza patients. RESULTS: Three hundred fifty‐one patients with SARS‐CoV‐2 and 258 with influenza were included in the final analysis. CK was elevated in 27% of COVID‐19 and in 28% of influenza patients. CK was higher in severe COVID‐19 as were markers of inflammation. CK correlated significantly with inflammation markers, which had an independent impact on CK when adjusted for demographic variables and disease severity. Compared to influenza patients, COVID‐19 patients were older, more frequently male, had more comorbidities, and more frequently had a severe disease course. Nevertheless, influenza patients had higher baseline CK than COVID‐19, and 35.7% of intensive care unit (ICU)‐admitted patients had CK levels >1,000 U/L compared to only 4.7% of ICU‐admitted COVID‐19 patients. CONCLUSIONS: HyperCKemia occurs in a similar frequency in COVID‐19 and influenza infection. CK levels were lower in COVID‐19 than in influenza in mild and severe disease. CK levels strongly correlate with disease severity and markers of inflammation. To date, it remains unclear whether hyperCKemia is due to a virus‐triggered inflammatory response or direct muscle toxicity.