#1898 Investigating the skeletal muscle and kidney function crosstalk in survivors of critical illness

Abstract Background and Aims The skeletal muscles and kidneys are frequently affected during critical illness, yet their crosstalk remains poorly explored in the long-term. We investigated the crosstalk between skeletal muscle and kidney function in survivors of COVID-19. Methods A cross-sectional analysis of a prospective cohort study with survivors of moderate to severe COVID-19 hospitalization in São Paulo, Brazil. Skeletal muscle assessments included handgrip strength, calf circumference, ultrasound-measured quadriceps thickness, and gait speed. Probable and confirmed sarcopenia were assessed by modified European Working Group on Sarcopenia in Older People (EWGSOP2). Kidney function was assessed by estimated glomerular filtration rate (eGFR), urinary albumin-to-creatinine ratio (UACR), and urine sediment. Abnormal kidney function was defined as an eGFR <60 mL/min/1.73 m2, albuminuria (≥30 mg/g), and leukocyturia and/or hematuria. Results 743 survivors (46% female, 43% ≥60 years, 35% with diabetes) were assessed 7 ± 2 months post-hospital discharge. Positive significant associations with eGFR were observed for calf circumference (β = 0.42 ml/min/1.73 m2, 95% CI: 0.06 to 0.78) and thicknesses (mm) of rectus femoris (β = 0.47, 95% CI: 0.01 to 0.94) and vastus intermedius (β = 0.55, 95% CI: 0.14 to 0.96). None of the skeletal muscle parameters were associated with UACR (mg/g). Survivors with sarcopenia (35% probable + 6% confirmed) had lower eGFR (‒9.9 ml/min/1.73 m2, 95% CI: ‒14.4 to ‒5.5) and a higher prevalence of low eGFR (26% vs. 15%; P < 0.001) as compared to those without sarcopenia, but similar frequencies of albuminuria and abnormal urine sediment. Sarcopenia was associated with a higher odd for low eGFR (adjusted odds ratio = 1.83, 95% CI: 1.25 to 2.70), but not with albuminuria nor abnormal urine sediment. Conclusion In survivors of moderate to severe COVID-19 hospitalization, muscle mass parameters were associated with eGFR, and those with sarcopenia exhibited lower eGFR, suggestive of chronic kidney disease. These findings suggest the existence of a muscle-kidney crosstalk in this population; moreover, sarcopenia should be considered a significant factor for chronic kidney disease.