Background Non-alcoholic fatty liver disease (NAFLD) is becoming increasingly prevalent worldwide, even among young adults. This condition shares many risk factors with other metabolic disorders, including cardiovascular disease (CVD), but researchers suggest the presence of NAFLD itself may be a risk factor for developing CVD, independently of other established factors.

Methods In this prospective, general population-based cohort study of young adults in the UK, transient elastography-defined liver steatosis and fibrosis were assessed at age 24 years, as were cardiovascular structure and function, measured using echocardiography, carotid ultrasonography and pulse wave analysis. We examined associations between liver and cardiovascular health, with and without accounting for age, sex, ethnicity, social class, employment, body mass index, alcohol, smoking, blood pressure, fasting serum lipids, fasting glucose, fasting insulin and C-reactive protein. All participants with harmful alcohol consumption or viral hepatitis were excluded from analysis. Pregnant participants were also excluded from ultrasonography and therefore could not be included.

Results A total of 2,047 young adults (mean age 24.4 years; 36.2% female) from the Avon Longitudinal Study of Parents and Children (ALSPAC) were included; 406 (19.8%) had liver steatosis, while 38 (1.9%) had liver fibrosis F2 or greater. After full-adjustment for established cardiovascular risk factors, steatosis was only associated with a decrease in stroke volume index (adjusted mean difference [95% CI] of -1.21 [-2.14, -0.10] mL/m2). All other associations of steatosis with cardiovascular outcomes were null in our fully-adjusted model. Liver fibrosis, however, was associated with several measures of cardiac structure and function, as well as subclinical atherosclerosis. Compared to F0/F1 fibrosis without septa, presence of F2-F4 fibrosis was associated with lower cardiac output index (adjusted mean difference [95% CI] of -0.22 [-0.39, -0.05] L/min/m2) and with greater tricuspid annular plane systolic excursion (adjusted mean difference [95% CI] of 0.13 [0.01, 0.25] cm), left ventricular mass index (adjusted mean difference [95% CI] of 2.02 [0.06, 3.99] g/m2.7), mitral valve E/A ratio (adjusted mean difference [95% CI] of 0.30 [0.12, 0.48]), carotid intima-media thickness (adjusted mean difference [95% CI] of 0.02 [0.01, 0.04] mm) and carotid-femoral pulse wave velocity (adjusted mean difference [95% CI] of 0.42 [0.08, 0.76] m/s) after full-adjustment for covariates.

Conclusions Liver fibrosis, but not steatosis, was associated with more adverse cardiovascular health in young adults once known confounders such as adiposity were accounted for. Further follow up of this and similar cohorts will be important to determine whether cardiovascular health worsens over time in those with steatosis alone, once accounting for other cardiovascular risk factors.

Conflict of Interest None