Although an increased body mass index is associated with lower mortality in patients undergoing hemodialysis (HD), known as the "obesity paradox," the relationship of abdominal fat levels with all-cause mortality has rarely been studied. We investigated the impact of computed-tomography-measured abdominal fat levels (visceral fat area (VFA) and subcutaneous fat area (SFA)) on all-cause mortality in this population. A total of 201 patients undergoing HD were enrolled and cross-classified by VFA and SFA levels according to each cutoff point, VFA of 78.7 cm² and SFA of 93.2 cm², based on the receiver operator characteristic (ROC) curve as following; group 1 (G1): lower VFA and lower SFA, G2: higher VFA and lower SFA, G3: lower VFA and higher SFA, G4: higher VFA and higher SFA. During a median follow-up of 4.3 years, 67 patients died. Kaplan-Meier analysis revealed 10-year survival rates of 29.0%, 50.0%, 62.6%, and 72.4% in G1, G2, G3, and G4 (p < 0.0001), respectively. The adjusted hazard ratio was 0.30 (95% confidence interval [CI] 0.05-1.09, p = 0.070) for G2 vs. G1, 0.37 (95% CI 0.18-0.76, p = 0.0065) for G3 vs. G1, and 0.21 (95% CI 0.07-0.62, p = 0.0035) for G4 vs. G1, respectively. In conclusion, combined SFA and VFA levels were negatively associated with risks for all-cause mortality in patients undergoing HD. These results are a manifestation of the "obesity paradox."
Keywords: abdominal fat level; all-cause mortality; hemodialysis; obesity paradox; subcutaneous fat area; visceral fat area.