Time-trend Comparative Associations of Muscle Strength and Mass, Cardiorespiratory Fitness, and Physical Activity Level with 6-Year Clinical Outcomes and Quality of Life in Kidney Transplantation (FO026)

INTRODUCTION AND AIMS: Reduced muscle strength and mass, cardiorespiratory fitness (VO2max) and physical activity level (PAL) occur early in chronic kidney disease, exacerbate as disease progresses, impair quality of life (QoL), and increase morbidity and mortality. While transplantation restitutes renal function, the extent of muscle strength and mass, VO2max and PAL restoration post-transplantation is unclear. Their impact on transplantation outcomes remains incompletely elucidated. This study examines the longitudinal changes of muscle strength and mass, VO2max and PAL in kidney transplant recipients (KTRs) before and after transplantation; and assesses their impact on 6-year clinical outcomes and QoL.

METHODS: This single-centre prospective longitudinal study enrolled 27 living-donor KTRs [age=42±16 years; 59% male]. Muscle strength was determined by handgrip strength (HGS) and jumping mechanography-derived power (JMP). Muscle mass was analysed by dual-energy x-ray absorptiometry. VO2max was estimated by cardiopulmonary exercise testing. PAL was measured in metabolic equivalents (METs) by activity accelerometer. QoL was evaluated with short form (SF)-36. Measurements were taken 1 month pre-, 3 and 12 months post- transplantation. Follow-up data on 6-year hospitalisation rates due to infection, graft rejection and acute cardiovascular event were collected. Demographic, anthropometric, nutritional, biochemical and clinical predictors were assessed. ANOVA, covariate-adjusted linear and Cox regressions, and Kaplan-Meier analyses were performed.

RESULTS: Muscle strength, PAL and QoL scores increased post-transplantation [HGS (kg): 24±3, 27±4, 31±4; JMP (W/kg): 32±4, 34±5, 40±4; METs: 1.3±0.3, 1.6±0.4, 1.9±0.4; SF-36 scores: 55±20, 67±20, 82±14; p<0.05 for all]. No significant changes in VO2max and muscle mass were detected. Six-year hospitalisation rate was 48%. Pre-transplant muscle strength and PAL were associated with 6-year hospitalisation [HGS: HR=0.72; JMP: HR=0.81; METs: HR=0.57; p<0.01 for all] and QoL [HGS: b=1.9; JMP: b=1.4; METs: b=21.6; p<0.05 for all] after adjusting for covariates and their longitudinal changes respectively. Kaplan-Meier analyses depicted higher hospitalisation rates in KTRs with pre-transplant HGS [Figure 1], JMP and METs [Figure 2] <50th percentile [p<0.001 for all]. Pre-transplant VO2max and muscle mass did not predict hospitalisation and QoL.

CONCLUSIONS: Muscle strength and PAL improved after transplantation. Low muscle strength and PAL pre-transplantation adversely affected post-transplant morbidity and QoL. Promoting physical activity through strength training among potential KTRs may optimise transplantation outcomes.