title: Association between inflammatory markers and liver fat: The Multi-Ethnic Study of Atherosclerosis.
abstract: BACKGROUND
  Nonalcoholic fatty liver disease (NAFLD) is a common liver disease. Data is emerging that an independent association between markers of subclinical atherosclerosis and NAFLD exists and it may be considered as an independent predictor of cardiovascular (CV) outcomes. We aim to better characterize the relationship between NAFLD and inflammatory markers in a multi-ethnic cohort by assessing fatty liver on computed tomography (CT) scans.
  
  
  METHODS
  The Multi-Ethnic Study of Atherosclerosis (MESA) is a longitudinal, population-based study from four ethnic groups free of CV disease at baseline. The inflammatory markers studied include: C-reactive protein (CRP) and interleukin 6 (IL-6). On CT scans liver-to-spleen ratio (LSR: Hounsfield Units (HU) of the liver divided by HU of spleen) of <1 and liver attenuation of <40 HU were used as criteria for fatty liver. Unadjusted and adjusted multivariate linear and logistic regression analysis was performed.
  
  
  RESULTS
  4038 participants amongst 6814 MESA population with visible spleen on the CT scan, available CRP and IL-6 levels and no reported liver cirrhosis were included. The average age was 61 +/- 10 years, 37% Caucasians and 45% were males. Mean CRP and IL-6 were 2.36 mg/dl and 1.37 pg/ml respectively. 696 participants (17%) had LSR of <1 and 253 (6%) had liver attenuation of <40 HU. When using LSR <1 as a continuous variable, the correlation (adjusted odds ratio (OR)) with CRP >2.0 was 0.037 (95% CI: 0.02-0.054) and with IL-6 was 0.014 (95% CI: 0.004-0.023). On the other hand when presence and absence of LSR <1 was considered, higher ORs for association with CRP >2: 1.41 (95% CI: 1.16 to 1.73) and IL6:1.18 (95% CI: 1.05 to 1.31) were found. Similarly, the adjusted association of per unit decrease in liver attenuation with CRP>2 was 1.92 (95% CI: 1.20 to 2.63) while for IL-6 was 1.08 (95% CI: 0.69 to 1.47). When considering presence and absence of liver attenuation <40 HU the OR for CRP >2 was 2.27 (95% CI: 1.62 to 3.16) and for IL-6 was 1.33 (95% CI: 1.13 to 1.58).
  
  
  CONCLUSIONS
  CRP and IL-6 levels were found to be significantly associated with liver fat assessed on CT scan after adjusting for other risk factors for atherosclerosis.
authors.affiliation: Cardiovascular Imaging Fellow, Los Angeles Biomedical Research Institute at Harbor-UCLA Ronit Katz, DPhil.
authors.forename: Yasmin S
authors.initials: YS
authors.lastname: Hamirani
authors.affiliation: University of Washington, Seattle, WA.
authors.forename: Ronit
authors.initials: R
authors.lastname: Katz
authors.affiliation: Adjunct Assistant Professor of Medicine, Ciccarone Center for Preventive Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Khurram
authors.initials: K
authors.lastname: Nasir
authors.affiliation: Resident in Internal Medicine.
authors.forename: Irfan
authors.initials: I
authors.lastname: Zeb
authors.affiliation: Assistant Professor of Medicine, Ciccarone Center for Preventive Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Blaha
authors.affiliation: Professor of Medicine, Ciccarone Centre of Preventive Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Roger S
authors.initials: RS
authors.lastname: Blumenthal
authors.affiliation: University of Washington, Seattle, WA.
authors.forename: Richard N
authors.initials: RN
authors.lastname: Kronmal
authors.affiliation: Professor of Medicine, Los Angeles Biomedical Research Institute at Harbor-ULCA, Torrance, CA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Budoff
keywords: C reactive protein; Inflammation; Non-alcoholic fatty liver disease; computed tomography scan