Comparative Associations of Muscle Mass and Muscle Strength with Mortality in Dialysis Patients

Abstract

Background and objectives Reduced muscle mass and strength are prevalent conditions in dialysis patients. However, muscle strength and muscle mass are not congruent; muscle strength can diminish even though muscle mass is maintained or increased. This study addresses phenotype and mortality associations of these muscle dysfunction entities alone or in combination (i.e., concurrent loss of muscle mass and strength/mobility, here defined as sarcopenia).Design, setting, participants, & measurements This study included 330 incident dialysis patients (203 men, mean age 53613 years, and mean GFR 762 ml/min per 1.73 m 2 ) recruited between 1994 and 2010 and followed prospectively for up to 5 years. Low muscle mass (by dual-energy x-ray absorptiometry appendicular mass index) and low muscle strength (by handgrip) were defined against young reference populations according to the European Working Group on Sarcopenia in Older People.Results Whereas 20% of patients had sarcopenia, low muscle mass and low muscle strength alone were observed in a further 24% and 15% of patients, respectively. Old age, comorbidities, protein-energy wasting, physical inactivity, low albumin, and inflammation associated with low muscle strength, but not with low muscle mass (multivariate ANOVA interactions). During follow-up, 95 patients (29%) died and both conditions associated with mortality as separate entities. When combined, individuals with low muscle mass alone were not at increased risk of mortality (adjusted hazard ratio [HR], 1.23; 95% confidence interval [95% CI], 0.56 to 2.67). Individuals with low muscle strength were at increased risk, irrespective of their muscle stores being appropriate (HR, 1.98; 95% CI, 1.01 to 3.87) or low (HR, 1.93; 95% CI, 1.01 to 3.71).Conclusions Low muscle strength was more strongly associated with aging, protein-energy wasting, physical inactivity, inflammation, and mortality than low muscle mass. Assessment of muscle functionality may provide additional diagnostic and prognostic information to muscle-mass evaluation.

Functional and Cognitive Impairment, Frailty, and Adverse Health Outcomes in Older Patients Reaching ESRD—A Systematic Review

“…Only two studies used more objective assessment of physical performance by measuring HGS (41,42). In 330 patients, lower HGS (,20 kg in women and ,30 kg in men) at dialysis initiation was found to be significantly associated with a higher mortality risk compared with those with appropriate HGS (adjusted HR, 1.79; 95% CI, 1.09 to 2.94) (41).…”

Vitamin D, a modulator of musculoskeletal health in chronic kidney disease

“…Observational studies have shown an inverse correlation between muscle mass and blood levels of IL‐6 and C reactive protein in CKD patients,12, 107, 108 postulating inflammation as an additional cause of muscle wasting in this population 109, 110, 111. Although the process by which inflammation produces sarcopenia has not yet been identified, several mechanisms have been described, including activation of NF‐κβ and angiotensin II pathways,112, 113, 114 and the ATP‐dependent ubiquitin–proteasome system, which has been identified as the most important pathway for muscle wasting 115.…”

“…These observations collectively imply an integrated role of vitamin D for bone and muscle health. Such a role may have substantial clinical implications, especially for CKD patients, in which musculoskeletal alterations and their complications, including muscle pain and weakness, sarcopenia, fatigability, reduced exercise tolerance, fractures, and falls, adversely affect quality of life and survival 12, 13, 14, 15, 16, 17…”

Benefits of Physical Exercise in Patients with Chronic Kidney Disease and Hemodialysis: A Mini Review

“…With these tests it has been shown that for every 0.1 m/s decrease in gaitspeed, the risk of mortality increases by 26%, while a one-second increase in time-up-and-go test increases mortality by 8% [8]. Physical function and muscle strength do not necessarily depend on muscle mass; some studies have reported that the first one is a better predictor of mortality in patients with CKD [9,10].…”