One in Four People Worldwide Have Nonalcoholic Fatty Liver Disease

By Laura Newman

March 09, 2016

NEW YORK (Reuters Health) - As the global obesity epidemic continues to fuel development of metabolic disorders, the clinical and economic burden of nonalcoholic fatty liver disease (NAFLD) and its more severe form, nonalcoholic steatohepatitis (NASH), will become "enormous," researchers warn in a new paper.

"People with NASH are going on to have cirrhosis and liver-related cancers, creating an immense clinical and economic burden," Dr. Zobair M. Younossi, of Inova Health System in Falls Church, Virginia, told Reuters Health in a telephone interview. This burden is expected to grow astronomically.

In a meta-analysis, published online February 22 in Hepatology, Dr. Younossi and colleagues reviewed several databases worldwide for papers published between 1989 and 2015 that addressed the epidemiology and progression of NAFLD and NASH.

They excluded papers that exclusively recruited the morbidly obese, children, or people with diabetes. All studies that did not report results on screening for alcohol consumption were also excluded, as were papers with patients with hepatitis B and hepatitis C virus. Histological diagnosis through liver biopsy was used to establish NASH.

The initial search pulled 729 papers, and 86 were included in the analysis. Altogether more than 8.5 million patients were included in the analysis, with more than 8 million patients from North America, 265,510 from Asia, 230,685 from Europe, 250 from Africa, 1,592 from the Middle East, 424 from South America, and 42 from Oceania.

NAFLD prevalence pooled worldwide, diagnosed through imaging, was calculated to be 25.24%. Prevalence was highest in the Middle East and South America, and Africa had the lowest prevalence.

"In the Middle East and South America, these diseases go unrecognized," Dr. Younossi told Reuters Health.

NAFLD incidence, available only for Asia (China and Japan) and Israel, came to 52.34 per 1,000 person years for Asia and 28.01 per 1,000 for Israel.

Pooled overall NASH prevalence among biopsied NAFLD patients came to 59.10%. By region, prevalence came to 64.45% for Asia, 69.25% for Europe, and 60.64% for North America.

The most common medical comorbidities identified in the meta-analysis were obesity (51.34% NAFLD and NASH), type 2 diabetes (22.51% NAFLD, 43.63% NASH), hyperlipidemia (69.16% NAFLD, 72.13% NASH), hypertension (39.34% NAFLD, 67.97% NASH), and metabolic syndrome (42.54% NAFLD, 70.65% NASH).

Hepatocellular carcinoma incidence in the NAFLD group was estimated at 0.44 per 1,000 person-years and for NASH 5.29 per 1,000. Liver-specific mortality rates for NAFLD came to 0.77 per 1,000, and 15.44 per 1,000 person years for NASH.

Dr. Younossi said that "like cardiovascular disease and other fields, comorbidities like obesity as it affects the liver have to become a major target of public health programs. For NASH, a tremendous effort of drug development is under way." He anticipates that within the next five years, new drugs will be available.

Dr. Kathleen Viveiros, director of hepatology, Tufts New England Medical Center, Boston, told Reuters Health in a phone interview, "Everyone knows obesity is a problem. It needs to be targeted in a medical visit and patients need to be encouraged to lose weight. Even a 5% weight loss can be enough, but we should aim for at least a 10% decrease in weight to reduce risk for metabolic syndrome."

"Encouraging lifestyle changes is crucial for empowering patients, so that they can make choices about food choices and exercise." As for advances in the field of diagnosis and treatment, Dr. Viveiros also pointed to the new drugs in the pipeline. One shortfall, however, is "there still needs to be noninvasive imaging for diagnosis," she said.

This research was supported by the Beatty Liver and Obesity Research Fund and Liver Outcomes Research Fund, Inova Health System, and Gilead Sciences to the Center for Outcomes Research, Washington D.C. Dr. Younossi reported that he consults for Gilead and Intercept and advises Bristol-Myers Squibb and AbbVie.


Hepatology 2016.


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