Role of ethnicity in nonalcoholic fatty liver disease

The first study to examine nonalcoholic fatty liver disease (NAFLD) among different ethnic and racial groups in the United States finds that Hispanics may be at a higher risk of developing the condition. The study is published in Hepatology, the official journal of the American Association for the Study of Liver Diseases (AASLD). Published by John Wiley & Sons, Inc., Hepatology is available online via Wiley InterScience.

NAFLD, the most common liver disease in the U.S., is a condition associated with obesity and Type II diabetes in which fat accumulates in the liver. Although it is benign, its more advanced form, nonalcoholic steatohepatitis (NASH), can cause chronic liver disease, cirrhosis and cancer. In fact, one in every five cases of newly diagnosed chronic liver disease may be attributable to NAFLD. Previous studies of NAFLD have focused predominantly on Caucasians, while the current study focused on a variety of racial-ethnic groups.

This study, jointly conducted by researchers at the University of California at San Francisco, the Division of Research at Kaiser Permanente, and the Center for Disease Control and Prevention, examined 742 newly diagnosed cases of chronic liver disease between December 1998 and December 2000. The patients were members of the Kaiser Permanente Medical Care Program who participated in the Alameda County, CA Chronic Liver Disease Surveillance Study, one of three sites in the country performing surveillance of chronic liver disease. Participants were assigned a diagnosis of "definite" NAFLD if a liver biopsy confirmed the disease, and a diagnosis of "probable" if several other criteria were met, including elevation of liver enzymes, ultrasound or computerized tomography results consistent with fatty liver, type II diabetes, high cholesterol, and no significant alcohol use.

The findings showed that 333 (39.1 percent) of the newly identified cases of chronic liver disease met case definition for definite or probable NAFLD. Of the 159 patients from this group who agree to participate in the study, 45 percent were Caucasian (compared to 59 percent of the Kaiser Permanente membership) and 28.3 percent were Hispanic (compared to 10 percent of the membership). The proportion of Asians was similar between the NAFLD population and the Kaiser Permanente membership, while African-Americans accounted for 9 percent of the membership but just 3 percent of the NAFLD group, although the authors note that the number of participants was small.

"Epidemiological studies in patients with other types of chronic liver disease have shown that race-ethnicity can be predictive of disease complications and response to treatment," the authors note, adding that identifying racial-ethnic origins in NAFLD patients may lead to an improved understanding of the natural history and treatment of the disease. While they acknowledge that differences in healthcare-seeking behavior in people of different racial- ethnic groups may affect the rate at which NAFLD is diagnosed, they suggest that the higher proportion of Hispanics in the NAFLD group may indicate that this group is at a higher risk for the condition. In addition, Asian patients had a significantly lower body mass index (BMI) than other racial groups, suggesting that this group may require a lower cut-off of BMI when diagnosing the disease. The study was also the first to find that NAFLD was strikingly more common in Asian males than females.

The authors conclude: "Our findings highlight the need for increased awareness of NAFLD within minority racial-ethnic groups, the need for culturally sensitive educational programs aimed at the early recognition and prevention of NAFLD, as well as the need for ensuring adequate representation of different racial and ethnic groups in future clinical studies."