MP403LOWER-LIMB MUSCLE MASS IS A SURROGATE INDEX OF WALKING ABILITY OF PRESENT AND IN FUTURE IN HEMODIALYSIS PATIENTS

Abstract

Introduction and Aims: In hemodialysis patients, mortality rate is much higher than that in general population, and decreased activities of daily life (ADL) is associated with shorter life. Recent studies have shown that muscle mass volume is reduced in patients with chronic kidney disease. However, factors determining or predicting capacity of walking ability of present or in future, an important ADL factor, in hemodialysis patients remain unclear. Here, we examined relationship between walking ability, thigh muscle mass and power in hemodialysis patients. Methods: Patients who have taken regular hemodialysis in our institute and were able to walk by themselves were enrolled in this study. Nineteen patients in maintenance hemodialysis on out-patient basis were recruited to this study, and 2 patients were dropped out during the follow-up period of 3 years. Their capacity of walking abilities, lower-limb muscle mass and its power were measured just after this study started, and whether they can walk or not in daily life was surveyed after 3 years. Their functional capacities were assessed by 6-minute-walk (SMW) test and measurement of leg-flexing power and leg-extending power (LFP and LEP) of isotonic muscle contraction with CYBEX. Computed tomography (CT) was used for measurement of ratio of thigh muscle area to femoral shaft area (TMA/FSA). Results: Of 17 study subjects (68.7±11.3 years old, average ± standard deviation, 12 men and 5 wemen), four and five patients had history of cerebral infarction and cardiac surgery at the start of this study, respectively. There were no patients who manifested severe joint pain or symptoms of peripheral artery diseases or ischemic heart diseases. The history of hemodialysis was 73±46 months at the examination. Body height was 160.2±8.9 cm and dry weight was 52.4±8.6 kg. SMW distance was 409±95 m. and it was positively correlated with TMA/FSA (r=0.55, p<0.05) and LEP (r=0.67, p<0.05), although there was no correlation between SMW and LFP (r=0.16). Only upper half of TMA/FSA, but not SMW, LEP or LFP, had lower incapability of walk in daily life compared with the lower half (11.1 vs. 62.5 %, p<0.05). Conclusions: Thigh muscle mass and leg-extending power correlate with walking ability in hemodialysis patients. TMA/FSA and LEP appear to be surrogate markers of ADL. As patients with higher TMA/FSA tended to have a walking ability in daily life after 3 years, TMA/FSA also seems to be a prognostic index of ADL in future. Interventional studies are needed to demonstrate roles of TMA/FSA and LEP as determinants of walking ability in patients on hemodialysis.