Skeletal muscle-kidney crosstalk in a cohort of critical illness survivors

TL;DR

This study explores the link between muscle health and kidney function in people who survived severe COVID-19.

Contribution

The study reveals a connection between skeletal muscle mass and kidney function in long-term COVID-19 survivors.

Findings

Higher calf circumference and thigh muscle thickness were linked to better kidney function (eGFR).

Sarcopenia was not independently associated with poor kidney function markers like low eGFR or albuminuria.

Abstract

The skeletal muscles and kidneys are frequently affected during critical illness; however, their crosstalk remains poorly explored, especially in the long-term evolution. Therefore, we investigated the crosstalk between skeletal muscle and kidney function in COVID-19 survivors.

A cross-sectional analysis of a prospective cohort study with survivors of moderate to severe COVID-19 hospitalization. Skeletal muscle assessments included handgrip strength, calf circumference, ultrasound-measured quadriceps thickness, and gait speed test. Sarcopenia was diagnosed by modified EWGSOP2 (low handgrip strength plus low ultrasound-measured quadriceps thickness). Kidney function was assessed by estimated glomerular filtration rate (eGFR), urinary albumin-to-creatinine ratio (UACR), and urine sediment analysis. Abnormal kidney function was defined as an eGFR < 60 mL/min/1.73m2, albuminuria (≥30 mg/g), and/or leukocyturia or hematuria.

A total of 734 survivors (46% female, 43% ≥ 60 years, 35% with diabetes) were assessed 7 ± 2 months post-hospital discharge. Sarcopenia was diagnosed in 21.4% of the cohort. Positive significant associations with eGFR were observed for calf circumference (β = 0.42 ml/min/1.73m2, 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 had lower eGFR (‒5.8 ml/min/1.73m2, 95%CI: ‒10.8 to ‒0.9), but similar frequencies of low eGFR (24% vs. 18%; p = 0.137), albuminuria (27% vs. 31%; p = 0.434) and abnormal urine sediment (17% vs. 22%; p = 0.217) as compared to those without sarcopenia. Sarcopenia was not associated with higher odds of low eGFR, albuminuria, or abnormal urine sediment.

In survivors of moderate to severe COVID-19 hospitalization, skeletal muscle mass was associated with eGFR, whereas sarcopenia per se was not independently associated with poor kidney function. These findings suggest the existence of a skeletal muscle-kidney crosstalk in this population.

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