Muscle Mass, Muscle Strength, and Health-Related Quality of Life in Kidney Transplant Recipients: Results of the TransplantLines Biobank and Cohort Study

Abstract

IntroductionMuscles are crucial for daily activities, and kidney transplant recipients (KTR) often have reduced muscle mass and strength. We aimed to investigate the potential relationship of muscle mass and strength with physical health-related quality of life (HRQoL) in KTR. MethodsData from the TransplantLines Biobank and Cohort Studies were used. Muscle mass was assessed with appendicular skeletal muscle mass index (ASMI) and 24-hour urinary creatinine excretion rate index (CERI). Muscles strength was assessed by handgrip strength index (HGSI). HRQoL was measured using Short Form 36 physical component score (PCS). ResultsWe included 751 KTR (61% male, mean age 56±13y, median 3y post-transplant). Ordinary least squares regression analyses demonstrated that lower ASMI, CERI and HGSI were all non-linearly associated with lower PCS, independent of potential confounders and each other. Below median values, ASMI, CERI and HGSI were each associated with PCS, whereas above median values, associations were less pronounced. Compared to the 50th percentile, a decrease to the 10th percentile was associated with a decrease in PCS of 4.8% for ASMI (P=0.011), of 5.1% for CERI (P=0.008) and 13.2% for HGSI (P<0.001), whereas an increase to the 90th percentile was associated with an increase in PCS of only 0.7% for ASMI (P=0.54), of 3.6% for CERI (P=0.05) and -0.4% for HGSI (P=0.73). ConclusionsLow muscle mass and strength are potentially modifiable risk factors for impaired physical HRQoL in KTR. The non-linear associations suggest that KTR with low muscle mass or strength may particularly benefit from (p)rehabilitation interventions to improve HRQoL.