'Alarming' Global Rise in NAFLD 

Megan Brooks

July 11, 2022

The global prevalence of fatty liver disease not due to alcohol is considerably higher than previously estimated and is continuing to increase at an alarming rate, report researchers from Canada.

Their analysis suggests nearly one third of the global general adult population has nonalcoholic fatty liver disease (NAFLD), with men much more likely to have the disease than women.

"Greater awareness of NAFLD and the development of cost-effective risk stratification strategies are needed to address the growing burden NAFLD," write Abdel-Aziz Shaheen, MBBCh, MSc, and colleagues with the University of Calgary.

The study was published online July 4 in Lancet Gastroenterology and Hepatology.

NAFLD is the most common liver disease worldwide and a leading cause of liver-related illness and death. Yet, high-quality reports on the epidemiology of NAFLD at a global level are scarce and temporal trends of the NAFLD burden, including by gender, have not been described, until now.

Using MEDLINE, EMBASE, Scopus, and Web of Science, the Calgary team identified reports on NAFLD incidence and prevalence in study populations representative of the general adult population published between the date of database inception to May 25, 2021.

In total, 72 publications, with a sample population of more than 1 million adults from 17 countries, were included in the prevalence analysis, and 16 publications, with a sample population of nearly 382,000 individuals from five countries, were included in the incidence analysis.

By their estimates, the overall global prevalence of NAFLD is 32.4%, with prevalence increasing steadily and significantly over time, from 25.5% in or before 2005 to 37.8% in 2016 or later. The overall prevalence is significantly higher in men than in women (39.7% vs 25.6%).

These figures contrast with recent meta-analyses and systematic reviews that put the global prevalence of NAFLD at between 25.2% and 29.8%. However, these studies had "considerable" limitations with "potentially biased inferences," Shaheen and colleagues note.

By region, their data put the prevalence of NAFLD at 31.6% in Asia, 32.6% in Europe, 47.8% in North America, and 56.8% in Africa.

Shaheen and colleagues estimate the overall incidence of NAFLD to be 46.9 cases per 1000 person-years, with a higher incidence in men than women (70.8 vs 29.6 cases per 1000 person-years), in line with the gender differences in prevalence.

They caution that there was "considerable" heterogeneity between studies in both NAFLD prevalence and incidence (I2 = 99.9%) and few "high-quality" studies.

Despite these limitations, Shaheen and colleagues say the rise in NAFLD prevalence "should drive enhanced awareness of NAFLD at the level of primary care physicians, public health specialists, and health policy makers to encourage the development of more effective preventive policies."

Funding for the study was provided by the Canadian Institutes of Health. Shaheen has received research grants from Gilead and Intercept, and honoraria from SCOPE Canada.

Lancet Gastro Hepatol. Published online July 4, 2022. Abstract

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