Comparison of cardiovascular mortality between MAFLD and NAFLD: A cohort study
Introduction
The prevalence of fatty liver disease (FLD) is increasing worldwide owing to the widespread western lifestyle, increased prevalence of obesity and type 2 diabetes, and related metabolic derangements [[1], [2], [3], [4]]. Traditionally, two major categories existed in FLD: non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD) [5,6]. Although this classification of FLD has been used for nearly 35 years, it has a blind spot because NAFLD does not include FLD with other coexisting liver diseases or moderate alcohol intake [7]. This problem led to the development of a new class of FLD, known as metabolic dysfunction-associated fatty liver disease (MAFLD) [7,8] to include these patient populations that were previously challenging to classify.
The newly proposed definition of MAFLD consists of hepatic fat and metabolic abnormalities regardless of alcohol consumption or secondary causes of liver diseases and steatosis [7,9]. This new definition is expected to facilitate the identification of patients with FLD with chronic liver diseases or alcoholism, which were previously excluded by the traditional NAFLD definition [9]. However, this change has also provoked new concerns. Younossi et al. suggested that this change is premature because the new terminology was created without evidence of the pathogenesis of MAFLD or the effect of MAFLD on long-term complications [10].
Many researchers have investigated the association between FLD and cardiovascular disease (CVD) mortality [[11], [12], [13], [14]]. Growing evidence suggests that patients with NAFLD are at increased risk of developing type 2 diabetes, coronary artery disease, cardiomyopathy, and cardiac arrhythmias, which may lead to increased CVD mortality [7,[15], [16], [17]]. These findings suggest that NAFLD is a predictor of CVD events, independent of traditional risk factors [14,18].
Considering the new definition of MAFLD, one could speculate that MAFLD is associated with higher CVD mortality, as it incorporates a wider range of patients with FLD with metabolic derangements [7]. However, data on CVD mortality in the MAFLD population are limited [7]. There is debate over whether the MAFLD definition predicts CVD mortality better than the NAFLD classification [7]. To clarify this ambiguity, we conducted a large-scale cohort study to assess the relationship between FLD and CVD mortality.
Section snippets
Study population
The Kanbguk Samsung Health Study (KSHS) data were used for our analysis. The cohort and methods have been described in a previous study by our team [19]. In brief, the KSHS cohort was created using data from regular comprehensive health examinations among employers in Korea's public or private sectors. All examinations were conducted at two health examination centers in South Korea. Extensive information was collected using a standardized questionnaire during the health examination, including
Baseline characteristics
The median follow-up duration was 8.77 years, and the mean follow-up duration was 9.24 ± 5.26 years. The mean age of the participants was 39.81 ± 10.92 years, and 52.56% (n = 368,824) were men (Supplemntary Table 1). Among the 701,664 study participants, participants were stratified into no-MAFLD (n = 523,933, 74.67%), and MAFLD (n = 177,731, 25.33%) group. The proportions of men (76.73%), smokers (30.64%), and individuals with high alcohol consumption (16.4%) were higher in the MAFLD group
Discussion
To our knowledge, this was one of the major studies to date that showed the association between MAFLD and the risk of CVD mortality in a cohort of individuals who underwent liver ultrasonography to define hepatic steatosis. In our study cohort, the presence of MAFLD was associated with an increased risk of CVD mortality, whereas the presence of NAFLD did not show any such significant association. When we divided the participants into 5 categories, the MAFLD-only group was associated with an
Conclusions
In conclusion, our study showed that the presence of MAFLD was associated with increased CVD mortality in a relatively young Korean population. However, the strength of this association was not strong. Therefore, careful application of MAFLD for CVD risk prediction is required.
Funding
None.
Author contributions
TKY: Conceptualization, methodology, writing – original draft, and writing – review and editing. MYL: Formal analysis and investigation. SHK: Writing – review and editing; M-HZ: writing – review and editing; GT: writing – review and editing; CDB: writing – review and editing; K-CS: conceptualization, methodology, writing – review and editing, supervision, and project administration.
Ethical statement
The Institutional Review Board of Kangbuk Samsung Hospital (IRB No.:2022- 05- 024) approved the current study. Informed consent was waived because we used only non-identifiable data obtained during the health-screening examinations.
Data sharing statement
The data that support the findings of this study are available on request from the corresponding author, Ki-Chul Sung, upon reasonable request.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
None.
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