Evaluation of muscle strength and renal function in survivors of severe COVID-19: A 12-month follow-up study

Abstract

Introduction: Severe COVID-19 is known to cause kidney injury via ACE2-mediated mechanisms, inflammation, and microvascular damage potentially leading to long-term renal impairment. Critically ill patients are particularly vulnerable  to muscle loss and sarcopenia due to immobility, poor nutrition, and cytokine storm–induced catabolism. Post-COVID-19 syndrome often includes fatigue, muscle weakness, and reduced quality of life,  yet  evidence on long-term outcomes remains limited. This study evaluated kidney function, sarcopenia risk, and quality of life 12 months after intensive care unit (ICU) discharge in patients without pre-existing chronic kidney disease (CKD).
Methods: This retrospective observational cohort included 82 patients without CKD admitted to the ICU between February 2020 and April 2022 who recovered from severe COVID-19. Data collected included serum creatinine, estimated glomerular filtration rate (eGFR), and sarcopenia risk assessed via the SARC-CalF (SARC-F combined with calf circumference). Functional outcomes were assessed by SF-36, pain by a Visual Analog Scale (VAS), and lower limb strength by the 30-second sit-to-stand test.
Results: The mean age was 52 ± 12 years; 90% were male, 46% had hypertension, and 31% diabetes. At 12 months, patients showed low functional scores (SF-36: 47 ± 21), high pain prevalence (VAS: 57%), reduced lower limb strength (sit-to-stand: 8 ± 5 repetitions), and high sarcopenia risk (SARC-F: 46%). Higher sarcopenia scores correlated with poorer physical functioning (r = -0.60; p < 0.001) and greater pain (r = -0.44; p < 0.001). In 49 patients without hypertension, diabetes, or prior acute kidney injury (AKI), creatinine significantly increased (0.95 ± 0.2 to 1.10 ± 0.2 mg/dL; p = 0.007) and eGFR significantly declined (87 ± 22 to 77 ± 18 mL/min; p = 0.001), representing a mean reduction of 10 mL/min.