Nonalcoholic fatty liver disease (NAFLD) was present in approximately two-thirds of patients who did not undergo a liver biopsy. These patients were more likely to be non-White and older, as well as have normal ALT levels, which shows potential gaps in knowledge about this population.
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Data from studies of patients diagnosed with NAFLD that require biopsy among their inclusion criteria may be subject to selection and detection bias, wrote A. Sidney Barritt, MD, of the University of North Carolina at Chapel Hill, and colleagues. The researchers sought to compare characteristics of patients with NAFLD who were diagnosed using clinical criteria and those diagnosed via liver biopsy.
In a study published in Hepatology Communications, the researchers reviewed data from TARGET-NASH, a longitudinal, observational cohort study designed to follow patients with NAFLD in clinical practice to provide data on the effectiveness of treatments.
“TARGET-NASH represents a large cohort of NAFLD patients from multiple sites and can provide us with real world information on progression of disease in patients with NAFLD and particular risk factors that may be clinically relevant,” Zachary Henry, MD, MS, of the division of gastroenterology & hepatology at the University of Virginia Health System in Charlottesville, said in an interview. “This is one of the first studies from this database, and as time goes on, we will see more large-population data like this to answer specific questions for NAFLD patient.”
Surprising findings
The researchers included 3,474 patients aged 18 years and older who were enrolled in the TARGET-NASH study between Aug. 1, 2016, and March 4, 2019. The study participants were classified according to severity of liver disease: nonalcoholic fatty liver (30%), nonalcoholic steatohepatitis (37%), and NAFLD cirrhosis (33%).
A total of 766 patients were diagnosed with NASH based on clinical criteria without biopsy, and all met the criteria for abnormal ALT and steatosis based on imaging. In addition, these patients had at least one secondary diagnostic criteria: body mass index greater than 30 kg/m2 (74%), type 2 diabetes (42%), and dyslipidemia (54%). Significant independent predictors of liver biopsy included younger age, White race, female gender, diabetes, and elevated levels of ALT.
Elevated ALT increased the odds of liver biopsy by 14% per 10-point rise, according to the study. A machine learning model showed that non-White patients with ALT less than 69 IU/mL had a 6% chance of liver biopsy. By comparison, White patients had a 21% chance of biopsy with ALT between 29 IU/mL and 69 IU/mL that dropped to 10% if the ALT was less than 29 IU/mL.
However, ALT remains a “suboptimal surrogate” for disease severity, the researchers noted. “How a normal ALT is defined and how a normal ALT range may vary across different laboratories may play a role in its utility as a diagnostic tool as well.”
Dr. Henry was surprised by this finding: “With the advent of noninvasive measures of fibrosis, such as the NAFLD fibrosis score, Fibrosis-4, and transient elastography, I thought these would have a more significant role in that decision as opposed to ALT levels.”
Notably, mental health diagnoses accounted for nearly half (49%) of comorbid conditions, followed by cardiovascular disease (19%), and osteoarthritis (10%). The prevalence of these conditions emphasizes the challenges of managing patients with NAFLD with diet and exercise alone because mental and physical problems may impede progress, the researchers wrote.
The study findings were limited by several factors including the inability to determine health care provider intent, as well as undocumented factors related to patients and providers that might influence a biopsy decision, such as assessment of disease severity, the researchers noted. In addition, they noted that the mostly White study population treated in specialty settings might not generalize to other populations or primary care.
However, the findings are strengthened by the large study population and real-world setting, the researchers emphasized. “These data provide context for the selection bias that may be present in many registries and randomized, controlled trials of therapies for NAFLD, where biopsy is required for inclusion,” and show potential knowledge gaps about the patient population less likely to undergo biopsy.