Associations of Body Mass Index and Body Fat With Markers of Inflammation and Nutrition Among Patients Receiving Hemodialysis.

BACKGROUND: Understanding the extent to which visceral and subcutaneous body fat are associated with markers of nutrition and inflammation in patients on dialysis therapy could shed light on the obesity paradox and the biology of subcutaneous fat.

STUDY DESIGN: Cross-sectional.

SETTING & PARTICIPANTS: 609 adults receiving hemodialysis who participated in the ACTIVE/ADIPOSE Study.

PREDICTORS: Body mass index (BMI), waist circumference, and bioelectrical impedance spectroscopy-derived estimates of percent body fat.

OUTCOMES: C-Reactive protein (CRP), interleukin 6 (IL-6), prealbumin, albumin, leptin, and adiponectin concentrations.

MEASUREMENTS: We performed linear regression analyses to examine the extent to which proxies of visceral and subcutaneous fat were associated with inflammation, nutrition, and adiposity-related hormones.

RESULTS: BMI was directly associated with markers of inflammation (standardized estimate for ln[CRP in mg/L]: 0.30 [95% CI, 0.22-0.38] per 10kg/m2 ; for ln[IL-6 in pg/mL]: 0.10 [95% CI, 0.02-0.18] per 10kg/m2 ), but was not associated with markers of nutrition. BMI was also inversely associated with adiponectin and directly associated with leptin. With waist circumference and percent body fat (as a proxy of visceral and subcutaneous fat, respectively) modeled together, waist circumference was associated with markers of inflammation (standardized estimate for ln[CRP in mg/L]: 0.21 [95% CI, 0.09-0.34] per 10cm; for ln[IL-6 in pg/mL]: 0.18 [95% CI, 0.07-0.29] per 10cm), whereas percent body fat was not associated with CRP (standardized estimate for ln[CRP in mg/L]: 0.03 [95% CI, -0.10 to 0.15] per 1%) and was inversely associated with IL-6 (standardized estimate for ln[IL-6 in pg/mL]: -0.15 [95% CI, -0.27 to -0.02] per 1%). In addition, waist circumference was inversely associated with prealbumin and albumin (standardized estimates of -0.12 [95% CI, -0.23 to -0.02] mg/dL per 10cm and -0.17 [95% CI, -0.28 to -0.06] g/dL per 10cm, respectively), and percent body fat was directly associated with prealbumin and albumin (0.20 [95% CI, 0.07-0.32] mg/dL and 0.15 [95% CI, 0.02-0.28] g/dL per 1%, respectively). Higher waist circumference was associated indirectly with adiponectin and directly with leptin concentrations.

LIMITATIONS: Although the observed associations implicate visceral fat as the cause of inflammation, it cannot be determined in this cross-sectional study.

CONCLUSIONS: Proxies of visceral and subcutaneous fat appear to have opposing associations with biomarkers of inflammation and nutrition. Subcutaneous fat may be an indicator of nutritional status, and visceral fat, an indicator of inflammation.