Author: Dr. Edward Hsi / CEO Prof. Wang-Long Chuang
Some diseases are concerning not because they occur suddenly, but because they persist over time without being noticed.
Metabolic dysfunction–associated steatotic liver disease (MASLD) is a clear example. Most patients do not experience obvious symptoms in the early stages, and liver function tests may remain within normal ranges. Nevertheless, the disease often progresses quietly, gradually accumulating damage. When clinical problems finally become apparent, they are frequently accompanied by poor glycemic control, cardiovascular events, declining kidney function, and advanced liver outcomes such as fibrosis, cirrhosis, or hepatocellular carcinoma.
For this reason, both public health planning and clinical decision-making must begin by addressing a seemingly simple but critical question:
How severe is MASLD at present?
Closely following this is an equally important question:
How can we know?
When “Severity” Must Be Quantified: From Clinical Impressions to Actionable Indicators
Within healthcare and public health systems, disease severity cannot rely solely on clinical impressions from individual cases. Instead, it must be translated into measurable indicators that can be tracked, compared, and used to inform decisions. In the case of MASLD, disease severity is best understood across several complementary levels.
The first level concerns the scale of the disease within the population, that is, how many people are affected. This includes prevalence, which describes the proportion of individuals with fatty liver disease or meeting MASLD criteria at a given point in time, as well as incidence, which reflects how many people newly develop the disease each year. This level captures the overall reach of MASLD across the population.
The second level focuses on clinical outcomes and disease progression. MASLD is not limited to fat accumulation in the liver; it may progress to liver fibrosis, cirrhosis, and liver cancer. It is also closely associated with diabetes, cardiovascular disease, chronic kidney disease, and thoracic-related conditions. Clinical outcomes such as hospital admissions, emergency department visits, and mortality reflect the direct impact of MASLD on both health systems and patient survival.
The third level addresses the overall consequences of these outcomes, including healthcare expenditures, length of hospital stay, long-term medication use, and indirect effects such as productivity loss, caregiving burden, and impacts on families. While clinicians usually observe only a small part of these consequences in outpatient care, policy makers must consider their effects at the societal level. This need gives rise to the concept of disease burden.
What Is Disease Burden? Turning Impact Into Comparable Weight
Disease burden is a systematic approach that integrates the effects of disease on health, healthcare systems, and society into a form that can be measured, compared, and followed over time. Through disease burden analysis, we can address key questions: How does MASLD compare with other chronic diseases in terms of its impact on population health? Which regions and population groups face higher risks? After screening programs, health education, lifestyle interventions, and medical resources are implemented, does the overall burden change?
In practice, our center currently focuses on several foundational indicators, including the prevalence and incidence of MASLD, severe disease and complications (such as liver fibrosis, cirrhosis, hepatocellular carcinoma, and cardiovascular events), and mortality-related outcomes. We also assess premature death using years of life lost (YLL). In other words, the core purpose of disease burden assessment is to convert the impact of disease into information that can be quantified, compared, and monitored.
From Databases to Communities: Building a More Precise Picture
Relying solely on case data from a single hospital may overestimate severe disease while underestimating individuals with undiagnosed or mild conditions in the community. On the other hand, population surveys alone often lack detailed clinical outcomes and long-term follow-up. To address these limitations, our center adopts a research strategy that combines database-based estimation with local data calibration, allowing results to better reflect real-world conditions.
We integrate several large and representative data sources, including the Taiwan Biobank and the MJ Health Screening Biobank, linked with the National Health Insurance Database. These datasets provide information on healthcare visits, medication use, diagnoses, laboratory testing, imaging, hospitalizations, and surgical procedures. Through these analyses, we are able to identify populations with metabolic abnormalities, individuals with evidence of fatty liver, and those who have already developed fibrosis or other clinical complications.
Our findings indicate that MASLD risk is not evenly distributed across the population, but instead shows clear geographic clustering. Therefore, we further incorporate these data into a geographic information system (GIS) to create disease risk maps that support decision-making. These maps allow us to examine MASLD prevalence, complication rates, and hospitalization patterns across administrative regions, and to assess whether current healthcare resources and health promotion efforts align with areas of highest risk. The purpose of these maps is practical: to determine where resources should be prioritized and where interventions should begin.
From National Trends to Local Demonstration: Toward Actionable Health Strategies
By integrating data from the Taiwan Biobank and the MJ Health Screening Database, our center analyzed records from 497,305 individuals between 2001 and 2021. The average age of participants was 42.1 years, and 55.3% were female. The overall prevalence of MASLD in Taiwan was estimated at 36.3%. Mapping prevalence by administrative region revealed higher-risk areas in southern and eastern Taiwan, indicating regions that warrant particular attention. Trend analyses further showed that MASLD prevalence was consistently higher among men and increased significantly over time in both men and women.
Figure 1. Geographic distribution of MASLD prevalence in Taiwan.
Figure 2. Annual increase in MASLD prevalence over time.
After identifying national-level risk patterns and trends, we further sought to obtain more detailed, community-level data to support precision public health strategies. Initial efforts focused on collaboration with township-level health authorities in Pingtung County. This work integrates community screening and health examination results, registries for metabolic syndrome, hypertension, and diabetes management, as well as indicators of coverage and effectiveness of health promotion programs. Through this process of local calibration, we are gradually developing disease burden maps into tools that can be designed, implemented, and evaluated as part of city-level health strategies, with the goal of scaling this model nationwide.
Conclusion
The challenge of MASLD lies in its long-standing silence. The responsibility of our center is to make this silence measurable, to identify where risks are concentrated, and to establish clear priorities for intervention. By starting with disease burden, we aim to help society understand how serious MASLD truly is. Disease mapping then serves as a key tool for translating research findings into concrete action. Through this integrated approach, we seek to support the development of more forward-looking and precise metabolic health policies for Taiwan.