Table 1.

Studies evaluating associations between non-alcoholic fatty liver disease (NAFLD) and arterial stiffness.

Author, Year	Number of Participants and Methods of Liver Investigation	Study Design	Aims	Conclusions
Shiotani et al., 2005 [50]	353 young university Japanese adults, submitted to abdominal ultrasound.	Transversal	To evaluate the validity of noninvasive ba-PWV measurements in overweight young adults.	ba-PWV was increased in males with NAFLD and might conceivably be useful to predict NAFLD.
Salvi et al., 2010 [51]	220 participants (123 women), aged between 30 and 70 years, from the Cardio-gambettola observatory liver steatosis estimation (GOOSE) study, submitted to abdominal ultrasound.	Transversal	To evaluate the relationship between metabolic syndrome, NAFLD and subclinical vascular disease, evaluated by carotid IMT and cf-PWV.	A possible independent role of NAFLD in determining arterial stiffness.
Vlachopoulos et al., 2010 [52]	23 biopsy-proven NAFLD patients and 28 matched controls.	Transversal	To investigate associations between NAFLD and functional arterial changes and early atherosclerosis.	NAFLD was associated with endothelial dysfunction and aortic stiffness (cf-PWV).
Kim et al., 2012 [53]	4467 patients submitted to abdominal ultrasound.	Transversal	To evaluate the association of NAFLD and ba-PWV in patients with and without metabolic syndrome.	NAFLD was independently associated with increased ba-PWV, irrespective of multiple covariates, only in patients without metabolic syndrome.
Huang et al., 2012 [54]	8632 Chinese from a population-based sample; NAFLD detected by ultrasound.	Transversal	To evaluate associations between NAFLD and early atherosclerosis (carotid IMT and ba-PWV).	NAFLD was associated with increased carotid IMT and ba-PWV, independent of traditional CV risk factors and metabolic syndrome.
Lee et al., 2012 [55]	1442 healthy adults; NAFLD detected by ultrasound.	Transversal	To evaluate association between NAFLD and arterial stiffness (ba-PWV).	Arterial stiffness was associated with NAFD, independent of classical CV risk factors.
Huang et al., 2013 [56]	964 adolescents (17-year-olds) from an Australian birth cohort, submitted to abdominal ultrasound.	Transversal	To examine if NAFLD was associated with aortic PWV, independent of cardiometabolic factors.	Aortic PWV was related to the presence of NAFLD that was predicated by the presence of an adverse metabolic profile in adolescents.
Sunbul et al., 2014 [57]	100 patients with biopsy-proven NAFLD and 50 age- and sex-matched controls.	Transversal	To examine the relationship between aortic PWV and AIx, the histological severity of NAFLD and epicardial fat thickness (EFT).	Patients with NAFLD have an increased arterial stiffness, which reflects both the severity of liver fibrosis and increased EFT values.
Omelchenko et al., 2014 [58]	52 NAFLD patients detected by ultrasound.	Transversal	To evaluate associations between adiponectin levels and arterial stiffness parameters (cf-PWV and AIx).	Adiponectin remained a significant predictor of PWV, even after controlling for age and gender, suggesting an active role of adiponectin in the pathophysiology of vascular disease in NAFLD patients.
Yu et al., 2014 [59]	1296 non-obese, non-hypertensive, non-diabetic adults, NAFLD by ultrasound.	Transversal	To evaluate then association between NAFLD and arterial stiffness (ba-PWV).	NAFLD was associated with ba-PWV in Chinese individuals without obesity, hypertension and diabetes.
Chen et al., 2015 [60]	2550 participants with ultrasound-confirmed NAFLD from a community-based sample.	Transversal	To evaluate whether advanced fibrosis assessed by NAFLD fibrosis score was associated with subclinical atherosclerosis in NAFLD patients.	Advanced fibrosis was associated with carotid intima media thickness, the presence of carotid plaques and arterial stiffness, independent of cardiometabolic risk factors and insulin resistance.
Chou et al., 2015 [61]	4860 non-diabetic, pre-diabetic and newly-diagnosed T2DM individuals, evaluated by abdominal ultrasound.	Transversal	To evaluate PWV in patients with NAFLD.	The effect of NAFLD on arterial stiffness was apparent only in subjects with normal glucose tolerance.
Ozturk et al., 2015 [62]	61 biopsy-proven NAFLD patients and 41 controls without NAFLD; adult male patients between 20 and 40 years of age.	Transversal	To evaluate the relationship between NAFLD and subclinical atherosclerosis and to investigate the associations according to the presence or absence of metabolic syndrome.	The presence of NAFLD was associated with endothelial dysfunction and atherosclerosis, independent of metabolic syndrome.
Chung et al., 2015 [63]	2954 healthy individuals; NAFLD detected by ultrasound.	Transversal	To evaluate the association between NAFLD and arterial stiffness (cardio-ankle vascular index).	NAFLD was associated with increased arterial stiffness, independent of cardio-metabolic risk factors.
Li et al., 2015 [64]	728 men and 497 women without hypertension and diabetes; NAFLD detected by ultrasound.	Longitudinal	To evaluate the relationship between the presence of NAFLD at baseline and progression of arterial stiffness (ba-PWV) during follow-up (5 years).	Patients with NAFLD had a faster progression of arterial stiffness, independent of other CV risk factors.
Leite et al., 2015 [65]	291 T2DM patients; NAFLD by abdominal ultrasound or liver biopsy.	Longitudinal	To evaluate the association between progressions of aortic PWV (7 years of follow-up) with advanced liver fibrosis identified by transient elastography.	High or increasing aortic stiffness predicted the development of advanced liver fibrosis on transient elastography.

Abbreviations: T2DM, type-2 diabetes mellitus; NAFLD, non-alcoholic fatty liver disease; cf-PWV, carotid-femoral pulse-wave velocity; ba-PWV, brachial-ankle pulse wave velocity; AIx, arterial augmentation index; IMT, intima media thickness.