In this study, we identified an association between MASLD and the presence and severity of CAC. In addition, we found that MASLD has a cardiovascular risk comparable to that of MAFLD but tends to outperform MAFLD in the assessment of CVD severity using the CAC score. This suggests that MASLD, as a novel nomenclature, has the potential to replace MAFLD when predicting the CVD risk.
This study has some clinical implications. First, the prevalence of MASLD in the two health-promotion centre populations was 32.6%. In two recent studies, the prevalence of MASLD was 33.4% in a Brazilian cohort and 14.87% in a Chinese cohort16,17. These discrepancies are possibly due to differences in the enrolled populations, including the timing of cohort recruitment and ethnic differences. Moreover, compared to a previous meta-analysis that reported the prevalence of MAFLD to be 38.77% (95% CI, 32.94–44.95%)18, the prevalence of MAFLD in our study was slightly higher at 45.2%. Additionally, the prevalence of overlap between MASLD and MAFLD in our study was 30.7%, which was comparable to that between traditional NAFLD and MAFLD (27.4%) in a previous study7. Further research is required to investigate the prevalence of MASLD in a large population cohort that reflects sex- and ethnicity-specific characteristics.
When compared with the non-MASLD or non-MAFLD groups, both the MASLD (odds ratio [OR], 1.21; 95% CI, 1.02–1.44) and MAFLD (OR, 1.20; 95% CI, 1.01–1.42) groups showed an ASCVD risk score-adjusted association with the presence of CAC. Similarly, both MAFLD and NAFLD have been associated with an approximately 1.2 to 2–fold increased risk of CVD in previous studies9,19,20. A previous meta-analysis revealed an association between the presence of CAC (OR, 1.272; 95% CI, 1.114–1.452), severe CAC defined as CAC > 100 (OR, 1.242; 95% CI, 1.017–1.516) and NAFLD, irrespective of traditional risk factors, which is similar to our results21.
However, in the present study, MASLD showed an ASCVD risk score-adjusted association with severe CAC (OR, 1.38; 95% CI, 1.01–1.89), whereas MAFLD did not (OR, 1.15; 95% CI, 0.84–1.57). These results may be related to the heterogeneous subtypes of MAFLD. Among the three MAFLD subtypes, diabetes is the most well-established risk factor for CAC, and the MAFLD-diabetic subtype is associated with an increased risk of all-cause mortality and CVD11,22. However, recent research indicates that the MAFLD-overweight/obese subtype does not increase the risk of all-cause mortality or cardiovascular morbidity10,11. Additionally, the MAFLD-lean subtype with less than two metabolic factors is not associated with CAC11. To investigate the association between the presence of CAC and MAFLD subtypes, we divided the MAFLD group into diabetic and non-diabetic subgroups. We found that the presence of CAC was significantly associated with the MAFLD-diabetic subtype when adjusted for age and sex, but not with the MAFLD-non-diabetic subtype when unadjusted (Supplementary Table 1). This implies that the associations of overall MAFLD with severe CAC may differ due to its heterogeneous subtypes, indicating that MASLD may be more effective than MAFLD when evaluating the severity of CVD. Moreover, a previous study suggested that light and moderate alcohol consumption may have a protective effect on CVD mortality23. Therefore, MAFLD may be associated with a reduced risk of CAC due to the higher proportion of light-to-moderate drinkers than in patients with MASLD; however, further research is required to reflect the exact impact of alcohol intake on CAC.
Furthermore, our subgroup analysis revealed that only overlap between the MASLD and MAFLD groups was associated with the presence of CAC when neither group was used as a reference. However, the MASLD-only and MAFLD-only groups showed no association with CAC, which is a distinctive finding. Additionally, there was no evidence to suggest the superiority of CAC in the definition of either type of SLD through comparisons between the MASLD-only and MAFLD subgroups. Contrary to our findings, previous studies comparing the efficacies of NAFLD and MAFLD in predicting the risk of CVD showed that the MAFLD group and the overlap between the NAFLD and MAFLD groups were associated with an increased risk of CVD7,9. In one study, the aOR for a high ASCVD risk in the MAFLD-only and MAFLD groups were 3.26 and 3.14, respectively, using the NAFLD-only group as a reference group24. In addition, previous studies have shown that the MAFLD definition is more effective than the NAFLD definition when predicting the prognosis of other diseases25,26.
The subgroups in this study were characterised as follows: the MAFLD-only group included patients with metabolic risk factors and other aetiologies such as alcohol consumption and chronic hepatitis C, whereas the MASLD-only group had a comparatively favourable metabolic status, with all metabolic risk factors scoring 1. Compared to the definition of NAFLD, the MASLD definition is believed to more directly and comprehensively include the metabolic components of MAFLD, thereby homogenising the overlap of the metabolically unfavourable portions. In other words, groups other than the homogeneous groups (NAFLD-only and MAFLD-only) showed a favourable metabolic status when compared with the overlap group. Future studies should use large longitudinal data to determine the comparative associations between MASLD, MAFLD, and CVD risk.
In this study, we also compared the CAC risk of each MASLD and MAFLD adjusted for the presence of advanced fibrosis, defined as Fib-4 ≥ 2.67, in addition to traditional risk factors. NAFLD is known to be associated with both fatal and nonfatal CVD events, depending on the stage of liver fibrosis27. We have previously shown that significant fibrosis, as defined by MRE, is associated with the presence of CAC in patients with NAFLD28. Furthermore, considering that MAFLD may better identify significant liver fibrosis than NAFLD, the assessment of the fibrosis stage may be an important consideration when comparing CVD risk between MAFLD and MASLD29.
Our study had several limitations. First, this was a cross-sectional retrospective study that does not establish causality with CVD in patients with SLD. Second, we only included individuals who voluntarily visited the health-promotion centre and could afford the full test, including cardiac CT, which may have resulted in a selection bias. Third, this study was conducted in South Korea, potentially restricting the generalisability of the findings to the entire population. Therefore, prospective, well-designed longitudinal studies are warranted to validate the causal relationship between MASLD and the incident and prevalent CVD risks. Fourth, the subjects enrolled in this study did not meet the criteria for MAFLD owing to the lack of homeostasis model assessment of insulin resistance (HOMA-IR) measurements. However, owing to the high cost and complexity of this procedure, the use of IR markers as the primary test for identifying MAFLD in the general population is challenging. In contrast, the MASLD can identify and assess risk factors through simple blood tests and demographic measurements.
In conclusion, beyond being associated with the presence of CAC, independent of traditional risk factors, MASLD was more effective than MAFLD in identifying severe CAC. Moreover, compared with the definition of MAFLD, the new MASLD nomenclature might not show any gap in the prediction of CVD risk using the CAC score. Therefore, the assessment and stratification of CAC may be useful in predicting a high risk of CVD events in patients with MASLD.