Non-alcoholic fatty liver disease (NAFLD) is evident in around two thirds of people with overweight or obesity, according to the results of a meta-analysis published in The Lancet Gastroenterology & Hepatology.
“Obesity is a well-known risk factor associated with NAFLD,” Jingxuan Quek, MBBS, of the National University of Singapore, and colleagues wrote. “[T]hese findings could be pivotal in improving the stratification of the disease burden for future early clinical intervention in overweight and obese individuals, especially at the level of primary care.”
Arising from the accumulation of fat in the liver, NAFLD and its more severe form, non-alcoholic steatohepatitis (NASH), are responsible for a growing proportion of advanced liver disease worldwide, mirroring a global rise in obesity. As a result of inflammation, NAFLD can lead to liver fibrosis, cirrhosis and even liver cancer. With no effective approved medical therapies, management depends on lifestyle changes such as weight loss and exercise.
While people with overweight or obesity are known to be at greater risk for fatty liver disease, the incidence of NAFLD in this group is unclear.
Quek and colleagues performed a systematic review and meta-analysis to assess the global prevalence of NAFLD, non-alcoholic fatty liver (fat in the liver with little or no inflammation or liver damage) and NASH among people with overweight or obesity. They also examined the incidence of fibrosis among those with NAFLD in the study population.
The team searched the Medline and Embase databases from their inception through March 2022. They found 7,389 potentially relevant English-language studies, of which 151 met the criteria and were included in the analysis. The pooled population included a total of 101,028 people.
Among the study participants with overweight, 70% had NAFLD, 42% had non-alcoholic fatty liver and 34% had NASH. The proportions were similar among those with obesity: 75%, 43% and 34%, respectively. NAFLD incidence in people with overweight was greatest in the Americas.
Looking at liver complications, 20% of people with overweight and NAFLD and 22% of those with obesity and NAFLD had some degree of clinically significant liver fibrosis (Stage F2 to F4). Further, 6.7% of people with overweight and NAFLD and 6.9% of those with obesity and NAFLD had advanced fibrosis (Stage F3) or cirrhosis (Stage F4).
“This study summarizes the estimated global prevalence of NAFLD, [non-alcoholic fatty liver] and NASH in overweight and obese individuals; these findings are important for improving the understanding of the global NAFLD burden and supporting disease management in the at-risk overweight and obese population,” the researchers wrote.