Mid-arm muscle circumference and quality of life and survival in maintenance hemodialysis patients

Abstract

Background and objectives: Maintenance hemodialysis (MHD) patients with larger body or fat mass have greater survival than normal to low mass. We hypothesized that mid-arm muscle circumference (MAMC), a conveniently measured surrogate of lean body mass (LBM), has stronger association with clinical outcomes than triceps skinfold (TSF), a surrogate of fat mass.

Design, settings, participants, & measurements: The associations of TSF, MAMC, and serum creatinine, another LBM surrogate, with baseline short form 36 quality-of-life scores and 5-year survival were examined in 792 MHD patients. In a randomly selected subsample of 118 subjects, LBM was measured by dual-energy x-ray absorptiometry.

Results: Dual-energy x-ray absorptiometry-assessed LBM correlated most strongly with MAMC and serum creatinine. Higher MAMC was associated with better short form 36 mental health scale and lower death hazard ratios (HRs) after adjustment for case-mix, malnutrition-inflammation-cachexia syndrome, and inflammatory markers. Adjusted death HRs were 1.00, 0.86, 0.69, and 0.63 for the first to fourth MAMC quartiles, respectively. Higher serum creatinine and TSF were also associated with lower death HRs, but these associations were mitigated after multivariate adjustments. Using median values of TSF and MAMC to dichotomize, combined high MAMC with either high or low TSF (compared with low MAMC/TSF) exhibited the greatest survival, i.e., death HRs of 0.52 and 0.59, respectively.

Conclusions: Higher MAMC is a surrogate of larger LBM and an independent predictor of better mental health and greater survival in MHD patients. Sarcopenia-correcting interventions to improve clinical outcomes in this patient population warrant controlled trials.

Figure 1.

Scatter plots, regression line, and 95% CI, reflecting the correlations between MAMC with BMI (top), NIR lean weight (middle), and serum creatinine concentration (bottom) in 792 MHD patients. Shaded areas reflect the 95% CIs.

Figure 2.

Spline model with 95% CIs reflecting adjusted mortality predictability of MAMC, expressed as a fraction of the average MAMC in the 792 MHD patients (from October 2001 to January 2007). Case-mix variables include age, gender, race/ethnicity, diabetes, dialysis vintage, insurance (Medicare), marital status, modified Charlson comorbidity score, dialysis dose (Kt/V), and kidney residual urine.

Figure 3.

Kaplan-Meier proportion of surviving MHD patients after 5 years of observation according to the quartiles of MAMC in 792 MHD patients (adjusted for case-mix and MICS). Case-mix variables: age, gender, race/ethnicity, diabetes mellitus, dialysis vintage, primary insurance, marital status, Charlson comorbidity score, dialysis dose (Kt/V), and kidney residual urine. MICS variables included serum phosphorus, albumin, creatinine, bicarbonate, calcium, ferritin, blood hemoglobin, white blood count, and lymphocyte percent; prescribed erythropoietin; normalized protein catabolic rate (nPCR), also known as normalized protein nitrogen appearance; and BMI.