A systematic review: burden and severity of subclinical cardiovascular disease among those with nonalcoholic fatty liver; should we care?

Background: Non-alcoholic fatty liver disease (NAFLD) is an emerging disease and a leading cause of chronic liver disease. The prevalence in the general population is approximately 15-30% and it increases to 70-90% in obese or diabetic populations. NAFLD has been linked to increased cardiovascular disease (CVD) risk. It is therefore critical to evaluate the relationship between markers of subclinical CVD and NAFLD.

Method: An extensive search of databases; including the National Library of Medicine and other relevant databases for research articles meeting inclusion criteria: observational or cohort, studies in adult populations and clearly defined NAFLD and markers of subclinical CVD.

Results: Twenty-seven studies were included in the review; 16 (59%) presented the association of NAFLD and carotid intima-media thickness (CIMT), 7 (26%) the association with coronary calcification and 7 (26%) the effect on endothelial dysfunction and 6 (22%) influence on arterial stiffness. CIMT studies showed significant increases among NAFLD patients compared to controls. These were independent of traditional risk factors and metabolic syndrome. The association was similar in coronary calcification studies. The presence of NAFLD is associated with the severity of the calcification. Endothelial dysfunction and arterial stiffness showed significant independent associations with NAFLD. Two studies argued the associations were not significant; however, these studies were limited to diabetic populations.

Conclusion: There is evidence to support the association of NAFLD with subclinical atherosclerosis independent of traditional risk factors and metabolic syndrome. However, there is need for future longitudinal studies to review this association to ascertain causality and include other ethnic populations.