Mortality Predictability of Body Size and Muscle Mass Surrogates in Asian vs White and African American Hemodialysis Patients

OBJECTIVE: Among chronic dialysis patients an obesity paradox or reverse epidemiology is known, but it is no clear whether the association of body size and muscle mass with survival is consistent across race, especially in East Asian versus Caucasian and African–American hemodialysis (HD) patients PATIENTS AND METHODS: Using 20,818 HD patients in South Korea from February 1, 2001 to June 30, 2009 and 20,000 matched HD patients in the United States (10,000 Caucasians and 10,000 African–Americans) from July 1, 2001 to June 30, 2006, we compared mortality associations of baseline body mass index (BMI) and serum creatinine (Cr) level, as likely surrogates of obesity and muscle mass across the three races. RESULTS: In Korean HD patients higher BMI together with higher serum Cr levels were associated with greater survival, as previously reported from US and European studies. In the matched cohort (n=10,000 in each of the three races), mortality risks were lower across higher BMI and serum Cr levels, and these association were similar in all three races (reference groups: patients with BMI >25.0 kg/m(2) or serum Cr >12 mg/dL in each race). Patients with BMI level ≤18.5 kg/m(2) (underweight) reported 78%, 79% and 57% higher mortality risk among Caucasian, African–American and Korean, respectively, and so did patients with serum Cr level ≤6.0 mg/dL, who reported 108%, 87% and 78% higher mortality, respectively. CONCLUSION: Race does not modify the association of higher body size and muscle mass with greater survival in HD patients. Given consistency of the obesity paradox, which may be related to mitigated effect of protein–energy wasting on mortality irrespective of racial disparities, nutritional support to improve survival should be tested across all races of HD patients

Serum creatinine level, a surrogate of muscle mass, predicts mortality in peritoneal dialysis patients

BACKGROUND: In hemodialysis patients, higher serum creatinine (Cr) concentration represents larger muscle mass and predicts greater survival. However, this association remains uncertain in peritoneal dialysis (PD) patients. METHODS: In a cohort of 10 896 PD patients enrolled from 1 July 2001 to 30 June 2006, the association of baseline serum Cr level and change during the first 3 months after enrollment with all-cause mortality was examined. RESULTS: The cohort mean ± SD age was 55 ± 15 years old and included 52% women, 24% African-Americans and 48% diabetics. Compared with patients with serum Cr levels of 8.0–9.9 mg/dL, patients with serum Cr levels of <4.0 mg/dL and 4.0–5.9 mg/dL had higher risks of death {HR 1.36 [95% confidence interval (95% CI) 1.19–1.55] and 1.19 (1.08–1.31), respectively} whereas patients with serum Cr levels of 10.0–11.9 mg/dL, 12.0–13.9 mg/dL and ≥14.0 mg/dL had lower risks of death (HR 0.88 [95% CI 0.79–0.97], 0.71 [0.62–0.81] and 0.64 [0.55–0.75], respectively) in the fully adjusted model. Decrease in serum Cr level over 1.0 mg/dL during the 3 months predicted an increased risk of death additionally. The serum Cr–mortality association was robust in patients with PD treatment duration of ≥12 months, but was not observed in those with PD duration of <3 months. CONCLUSIONS: Muscle mass reflected in serum Cr level may be associated with survival even in PD patients. However, the serum Cr–mortality association is attenuated in the early period of PD treatment, suggesting competing effect of muscle mass versus residual renal function on mortality