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Denominator bias in MENA MASLD epidemiology: A call for decision-grade surveillance

Mohamed El-Kassas^1,2, Khalid M AlNaamani^2,3, Faisal M Sanai^2,4

¹Department of Endemic Medicine, Capital University (Formerly Helwan University), Cairo, Egypt.

Saudi Journal of Gastroenterology : Official Journal of the Saudi Gastroenterology Association

|June 9, 2026

Abstract:

Metabolic dysfunction-associated steatotic liver disease (MASLD) is highly prevalent in the Middle East and North Africa (MENA) region, yet published estimates of prevalence and outcomes remain uncertain because the underlying denominators are inconsistently defined. This perspective argues that MENA MASLD epidemiology is systematically biased by three interacting mechanisms: distorted sampling frames, referral pathway selection, and structural undercapture of rural and displaced populations. Much of the current evidence is derived from convenience cohorts concentrated in urban, tertiary care settings where diagnostic availability and follow-up are greater than in the general population, leading to directional rather than random error. In parallel, risk stratification pathways that rely on two-step testing can funnel case detection toward specialty rich settings, overrepresenting advanced disease while missing earlier stages managed outside hepatology services. MASLD nomenclature change and incomplete alignment of coding and clinical documentation may further introduce artefactual inflection points that complicate trend interpretation. We highlight how underdiagnosis and under-recording in primary care propagate bias across downstream estimates and how validation of administrative algorithms and text-based ascertainment can quantify hidden disease reservoirs within routine data systems. Building on regional priority settings, we propose denominator-focused actions: probability-based sampling embedded in noncommunicable disease surveys; purposeful inclusion of rural and displaced groups; linkable data across primary care, laboratories, hospitals, and mortality registries; and harmonized coding and terminology. By decision-grade denominators, we refer to population denominators that are sufficiently representative, transparent, and linkable to support national surveillance, resource allocation, and trial-readiness decisions.

Insights

Estimates of metabolic dysfunction-associated steatotic liver disease (MASLD) in the Middle East and North Africa are biased by sampling and referral issues. Addressing these biases requires better population denominators for accurate MENA MASLD epidemiology.

Area of Science:

Hepatology and Gastroenterology
Public Health and Epidemiology
Metabolic Disorders

Background:

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing public health concern in the Middle East and North Africa (MENA) region.
Current prevalence and outcome data for MASLD in MENA are unreliable due to inconsistent population denominator definitions.
Systematic biases in epidemiological studies distort the understanding of MASLD's true burden in the region.

Purpose of the Study:

To identify and analyze the key mechanisms causing systematic bias in MENA MASLD epidemiology.
To propose actionable strategies for improving the accuracy of MASLD prevalence and outcome estimations in the MENA region.
To advocate for the development of "decision-grade denominators" for robust national surveillance and resource allocation.

Main Methods:

Perspective piece analyzing existing literature and epidemiological methodologies for MASLD in the MENA region.
Identification of three primary interacting mechanisms driving epidemiological bias: distorted sampling frames, referral pathway selection, and undercapture of specific populations.
Discussion of how nomenclature changes and data system limitations contribute to bias.

Main Results:

Epidemiological data are often derived from urban, tertiary care settings, overrepresenting advanced disease and underrepresenting milder forms and rural populations.
Risk stratification pathways and data system inconsistencies (coding, documentation) further introduce artefactual errors and complicate trend interpretation.
Underdiagnosis and under-recording in primary care significantly propagate bias in downstream estimates.

Conclusions:

Accurate MASLD epidemiology in MENA is hampered by biased data collection and definition of population denominators.
Recommendations include probability-based sampling, inclusion of rural/displaced populations, data linkage across healthcare settings, and harmonized terminology.
Implementing denominator-focused actions is crucial for reliable national surveillance, resource allocation, and clinical trial readiness.

Read full analysis

Keywords:

Burden MENA region denominator bias epidemiology metabolic dysfunction-associated steatotic liver disease (MASLD)prevalence

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