Objective: Muscle strength is frequently altered in hemodialysis patients. In the present work, five potential muscle biomarkers have been studied in their ability to assess muscular strength, muscular mass and to predict mortality of hemodialysis patients: activin-A, procollagen III N-terminal peptide, follistatin, myostatin and insulin-like growth factor-1 (IGF-1). Design and methods: Three independent cohorts of prevalent hemodialysis patients (2 from Li ege, Belgium and 1 from Marseille, France) were considered in this observational prospective study. The biomarkers were first measured in the Liege1 cohort. Two of them, myostatin and IGF-1, were then assessed in the whole population of patients (Liege1, Liege2 and Marseille). Muscle strength was assessed with handgrip strength (HGS) and muscle mass with bioimpedance analysis. One-year mortality predictive value of biomarkers was also studied in the Li ege1 and Marseille cohorts. Results: In the Li ege1 cohort (n567), HGS was only associated with concentrations of myostatin and IGF-1. These associations were confirmed in the whole population of 204 patients (r50.37, P,0.001 and r50.46, P,0.001, respectively) and remained significant (P,0.05) in multivariable models. The association between muscle mass and concentrations of myostatin and IGF-1were also significant. The ability of myostatin, IGF-1 and serum creatinine to detect a low HGS compared by Receiver Operating Characteristic curves analysis were not significantly different. Both myostatin and IGF-1 had a significant and comparable area under the curve to predict oneyear mortality: 0.73 (95% CI: 0.64 to 0.83) and 0.72 (95% CI: 0.61 to 0.82), respectively. Conclusion: Our results suggest that myostatin and IGF-1 are two biomarkers of interest to assess muscle status of dialysis patients. Both biomarkers are associated with HGS, muscular mass, and one-year mortality.

BackgroundHand grip strength (HGS) is a key measurement in the assessment of frailty phenotype in haemodialysis patients. However, the measurement is not very standardized, and notably, current data on the potential impact of a haemodialysis session on the results are both limited and controversial. In the present analysis, we compared HGS results before and after a haemodialysis session in 101 patients.MethodsIn the current observational study, HGS has been measured in adult haemodialysis patients on the same day, first before connection to the dialysis machine and then just after disconnection. At each timing, measurements were repeated three times with an interval of 5 s between measurements and the higher value was used for analysis.ResultsOne hundred and one patients (64% men) with a median (interquartile range, 25th percentile; 75th percentile) age of 66 (46; 76) years were included. In the whole population, a significant decline in HGS was observed after dialysis, with an absolute median decline of − 4 (0; −6) kg and a relative median difference of −11 (0; −20)%. These differences were observed in both genders and were independent of the baseline HGS value.ConclusionsOur results suggest that the timing (before or after the dialysis session) of hand grip assessment is clinically relevant and should be taken into account in clinical practice and also in epidemiological and clinical studies.

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