Nonalcoholic Fatty Liver Disease (MAFLD) and Long-Term Ambient Air Pollution Exposure: The Multi-Ethnic Study of Atherosclerosis (MESA)

摘要

Background: Animal studies have suggested that air pollution may cause metabolic changes including hepatic fat accumulation characteristic of insulin resistance in Type Ⅱ diabetes. This outcome has not previously been assessed in relation to air pollution. Aims: We performed a cross-sectional analysis to estimate the association between long-term ambient NOx and PM2.5 and fatty liver, as measured via computed tomography (CT). Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) is a population based cohort from 6 sites (n=6814). Participant exposures were annual average ambient PM2.5 and NOx concentrations estimated at year 2000 participant addresses using a likelihood-based land-use regression spatiotemporal model. The outcome was CT assessed liver density in Hounsfield units (HU), where liver attenuation less than 42 HU was considered to be non-alcoholic fatty liver disease (NAFLD). Logistic regression was used to assess the relationship between participant exposure and NAFLD. Individuals with excess alcohol consumption were excluded (men ＞14 drinks/wk and women ＞7 drinks/wk; remaining=6469). Primary models were adjusted for age at baseline, recruitment site, gender, race/ethnicity, educational attainment, BMI, waist circumference, smoking status, diabetes, HOMA-IR, HDL, and triglycerides. Results: Participants missing covariate values were excluded, resulting in a final sample size of 5558 for PM2.5 and 5484 for NOx. The adjusted OR of NAFLD for PM2.5 was 0.92 (95% CI: -0.84,1.00) for a 1 μg/m3 difference in PM2.5 (p=.O52). The adjusted OR for NOx was 0.99 (95% CI: 0.98,1.00) HU for a 1 ppm difference in NOx (p=.24). Site-adjusted models with fewer covariates were non-significant. Liver attenuation was also evaluated as a linear outcome and the results were similarly non-significant. In contrast, the adjusted OR of NAFLD for untreated diabetes was 2.28 (95% CI: 1.35, 3.85) compared to non-diabetics (p ＜ .01). Conclusions: Estimated air pollution exposure was not associated with fatty liver in this cross-sectional analysis.