Look Beyond Liver Biopsy for NAFLD Diagnosis

Heidi Splete

May 06, 2021

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.

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."

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.

Knowledge Gaps and Implications

The study is important because of the need to identify patient factors that predict histologic versus clinical diagnosis of NAFLD as the number of patient registries and clinical trials for NAFLD increase, Bubu Banini, MD, of Yale University, New Haven, Conn., said in an interview. "This information helps to elucidate selection and ascertainment bias and place findings from NAFLD registries and clinical trials into context."

Banini said that some of the findings were to be expected, while others were not.

"Historically, males and non-Whites are less likely to participate in registries and clinical trials, compared to females and Whites. However, I was surprised to find that these discrepancies further paralleled the likelihood of undergoing liver biopsy even among those who chose to participate. In addition, while mental health disorders (such as anxiety and depression) are a fairly prevalent comorbidity in patients with NAFLD, I was surprised to find that NAFLD patients with mental health disorders were more likely to undergo liver biopsy compared to those without these disorders. I would have expected the reverse," he noted.

"These findings highlight the gaps in knowledge regarding the impact of demographic and psychosocial factors on choice and assess to care among patients with NAFLD, and the need for further studies to address these gaps," she emphasized.

"A number of [studies] such as TARGET-NASH are doing away with the requirement for liver biopsy for participation; hence, it is less likely that selection bias related to liver biopsy would be a problem in these [studies] if clinical diagnosis is considered as a surrogate for histological diagnosis," Banini added.

"On the contrary, many NAFLD clinical trials require liver biopsy for inclusion." As nicely demonstrated in the current study, "this inclusion criterion may introduce selection bias," she said. "Awareness of potential biases would hopefully inform the design and recruitment strategy for registries and clinical trials in order to overcome these issues."

"I think the results of this study may actually point to a larger issue within medicine in general, which is a difference in care provided to minority communities," Henry said. "Whether this is intentional, related to unconscious bias on the part of providers, or related to a significant mistrust between minority communities and their health care providers is unclear but certainly needs to be addressed."

He noted that the purpose of TARGET-NASH is to enroll all patients with NAFLD regardless of biopsy. "Over time, as we have more data on these patients, we will have a better understanding of both diagnostic and therapeutic decisions in patients with NAFLD."

The study was supported by Target RWE, sponsor of the TARGET-NASH study. TARGET-NASH is a collaboration of academic and community investigators and the pharmaceutical industry. Lead author Barritt had no financial conflicts to disclose, but many study coauthors disclosed relationships with multiple pharmaceutical companies, including those involved in the TARGET-NASH study. Banini currently serves on the NASH advisory board for Boehringer Ingelheim. Henry reported no disclosures, although his institution is one of the enrollment sites for TARGET-NASH.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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