according to a new report.
An analysis of current drinkers in the Framingham Heart Study found that a higher number of drinks per week and higher frequency of drinking were associated with increased odds of fibrosis among patients whose consumption fell below the threshold for heavy alcohol use.
“Although the detrimental effects of heavy alcohol use are well accepted, there is no consensus guideline on how to counsel patients about how nonheavy alcohol use may affect liver health,” Brooke Rice, MD, an internal medicine resident at Boston University, said in an interview.
“Current terminology classifies fatty liver disease as either alcoholic or nonalcoholic,” she said. “Our results call this strict categorization into question, suggesting that even nonheavy alcohol use should be considered as a factor contributing to more advanced nonalcoholic fatty liver disease [NAFLD] phenotypes.”
The study was published online in Clinical Gastroenterology and Hepatology.
Analyzing associations
NAFLD and alcohol-related liver disease, which are the most common causes of chronic liver disease worldwide, are histologically identical but distinguished by the presence of significant alcohol use, the study authors wrote.
Heavy alcohol use, based on guidelines from the American Association for the Study of Liver Diseases, is defined as more than 14 drinks per week for women or more than 21 drinks per week for men.
Although heavy alcohol use is consistently associated with cirrhosis and steatohepatitis, studies of nonheavy alcohol use have shown conflicting results, the authors wrote. However, evidence suggests that the pattern of alcohol consumption – particularly increased weekly drinking and binge drinking – may be an important predictor.
Dr. Rice and colleagues conducted a cross-sectional study of 2,629 current drinkers in the Framingham Heart Study who completed alcohol-use questionnaires and vibration-controlled transient elastography between April 2016 and April 2019. They analyzed the association between fibrosis and several alcohol-use measures, including total consumption and drinking patterns, among nonheavy alcohol users whose liver disease would be classified as “nonalcoholic” by current nomenclature.
The research team defined clinically significant fibrosis as a liver stiffness measurement of 8.2 kPa or higher. For at-risk NASH, the researchers used two FibroScan-AST (FAST) score thresholds – greater than 0.35 or 0.67 and higher. They also considered additional metabolic factors such as physical activity, body mass index, blood pressure, glucose measures, and metabolic syndrome.
Participants were asked to estimate the frequency of alcohol use (average number of drinking days per week during the past year) and the usual quantity of alcohol consumed (average number of drinks on a typical drinking day during the past year). Researchers multiplied the figures to estimate the average total number of drinks per week.
Among the 2,629 current drinkers (53% women, 47% men), the average age was 54 years, 7.2% had diabetes, and 26.9% met the criteria for metabolic syndrome. Participants drank about 3 days per week on average with a usual consumption of two drinks per drinking day, averaging a total weekly alcohol consumption of six drinks.
The average liver stiffness measurement was 5.6 kPa, and 8.2% had significant fibrosis.
At the FAST score threshold of 0.67 or greater, 1.9% of participants were likely to have at-risk NASH, with a higher prevalence in those with obesity (4.5%) or diabetes (9.5%). At the FAST score threshold of greater than 0.35, the prevalence of at-risk NASH was 12.4%, which was higher in those with obesity (26.3%) or diabetes (34.4%).
Overall, an increased total number of drinks per week and higher frequency of drinking days were associated with increased odds of fibrosis.
Almost 17.5% of participants engaged in risky weekly drinking, which was defined as 8 or more drinks per week for women and 15 or more drinks per week for men. Risky weekly drinking was also associated with higher odds of fibrosis.
After excluding 158 heavy drinkers, the prevalence of fibrosis was unchanged at 8%, and an increased total of drinks per week remained significantly associated with fibrosis.
In addition, multiple alcohol-use measures were positively associated with a FAST score greater than 0.35 and were similar after excluding heavy alcohol users. These measures include the number of drinks per week, the frequency of drinking days, and binge drinking.
“We showed that nonheavy alcohol use is associated with fibrosis and at-risk NASH, which are both predictors of long-term liver-related morbidity and mortality,” Dr. Rice said.