ORLANDO – The risk factors for death in patients with nonalcoholic fatty liver disease include older age, male sex, truncal obesity, and a low HDL cholesterol level – in other words, the same factors that increase risk for death from cardiovascular disease and other causes, according to Dr. Naga P. Chalasani.
On the other hand, elevations in alanine aminotransferase (ALT) levels in patients with NAFLD are not associated with an increased risk for death or other poor outcomes, meaning that researchers may have to burrow more deeply through the available data to find risk predictors unique to NAFLD, said Dr Chalasani of Indiana University, Indianapolis.
Dr. Naga P. Chalasani
"How do we identify someone with NAFLD who is at risk for poor outcomes? I think this is the first shot at risk mapping patients," Dr. Chalasani said at the annual Digestive Disease Week.
Dr. Keith D. Lindor, who moderated the session at which the data were presented, agreed.
"What we’re having trouble with, I think, is defining nonalcoholic fatty liver disease easily, particularly amongst the population," he said. "We saw data that ALT, which we commonly used to use, may not be telling, and there are questions about how well ultrasound detects [NAFLD], particularly given that the amount of steatosis in order to be detected by ultrasound has to be relatively dramatic."
It is still not known whether people with steatosis discovered during biopsy but not visible on ultrasound will have risk factors similar to those of people with more grossly evident steatosis, he said in an interview.
Although Dr. Chalasani and colleagues failed to find unique risk markers in this population, it was not for want of trying. The investigators pored over data from the third National Health and Nutrition Examination Survey (NHANES III) for baseline and follow-up information about patients with NAFLD.
The data were collected from 1988 through 1994, and included gallbladder ultrasound with liver images in 14,797 adults aged 20-74. The authors linked the data to the National Death Index in an attempt to determine which factors might be harbingers of early mortality in patients with NAFLD vs. controls.
Dr. Keith Lindor
They defined NAFLD by the presence of moderate to severe hepatic steatosis on ultrasonography, and by the absence of iron overload, hepatitis B or C infections, and excessive alcohol consumption. Controls were participants in the same data set who did not have underlying liver disease and had normal ultrasound and liver function tests.
There were a total of 2,441 people with NAFLD and 8,423 controls. During a median follow-up of 14.3 years, 14% of controls (1,193), and 21% of those with NAFLD (501) died, a difference that was significant in a univariate analysis (P = .0328).
But when they looked at overall mortality, cancer-related mortality, and cardiovascular mortality, they found that all three categories shared male sex, older age, and a low HDL level as independent predictors for death, with cardiovascular mortality having the added bonus of the metabolic syndrome as an additional risk factor.
The authors did not disclose a funding source. Dr. Chalasani and Dr. Lindor reported having no relevant financial disclosures.