Skeletal muscle injury in COVID infection: Frequency and patterns

Little is known about skeletal muscle injury with coronavirus disease 2019 (COVID-19). We estimate the frequency and explore the patterns of skeletal muscle injury in acute COVID-19.

A cohort of COVID patients with mild to moderate symptoms were evaluated in a COVID-designated hospital between May and December 2021 and followed for 2 weeks. Skeletal muscle injury was assessed according to creatine kinase (CK) levels, Manual Muscle Test-8 (MMT-8) score, and the Health Assessment Questionnaire (HAQ) score. Injury was defined as CK >200 IU/L with an MMT-8 score < 76. The association between such injury and severity and outcomes were evaluated using cross-tabulations.

Two hundred fifty participants with a mean age of 50.2 years (SD: 17.2) were included. One hundred nine (43.6%) were women; 84 (34%) developed severe disease. Median CK levels were 91 IU/L (IQR 56-181). [Correction added on 17 November 2023, after first online publication: In the preceding sentence, the IQR was corrected from '56,181'.] Patients with weakness on the MMT-8 (n = 247, 98.8%) and disability on the HAQ (n = 107; 42.8%) were common. Neck flexor muscles were prominently affected. Skeletal muscle injury was seen in 22.4% (95% CI: 17.4-28.1). There was no significant association between skeletal muscle injury and maximal severity of illness or short-term outcomes. Disability increased over 14 days in most survivors (n = 172, 72.3%) and this was not seen in those with mild disease (OR: 0.4, 95% CI: 0.22-0.70).

Skeletal muscle injury appears to be common in people presenting with mild to moderate COVID infection.