Improving Early Detection of Nonalcoholic Steatohepatitis on Ultrasound

Nonalcoholic fatty liver disease (NAFLD) has become the most common form of liver disease in the United states, with its prevalence rising in conjunction with obesity rates. A lack of screening guidelines for fatty liver means it is most often diagnosed incidentally once patients show elevated liver enzymes or an echogenic liver on abdominal ultrasound. A recent study aims to improve the evaluation of fatty liver in abdominal imaging and identify factors that predict significant fibrosis and specialist referrals.

Patients with NAFLD are classified into 2 subgroups. NALFD is considered benign with low likelihood of progressive liver disease, and nonalcoholic steatohepatitis (NASH) is clinically significant and can lead to progressive liver fibrosis, cirrhosis, and eventually advanced disease and death. Often, patients with cirrhosis due to NASH have never had prior evaluation or diagnosis

“We know that for various medical conditions, failure to follow-up on specific imaging recommendations can result in delayed and sub-optimal care,” the study authors wrote. “Prior studies have suggested that over 10% of patients with incidental steatosis noted on imaging (done for non-hepatic reasons) ended up having advanced fibrosis on further evaluation.”

The retrospective study included 812 patients over a period of 18 months at the radiology and hepatology departments at Virginia Mason Medical Center. Patients with hepatic steatosis identified on ultrasound were “tagged” in the impression section of radiology reports, then researchers reviewed the charts of all patients who had abdominal ultrasound done for any reason and had the tag. Reports were reviewed at least 24 months post-scan to determine whether fatty liver was reported, if patients were referred to a hepatologist, and if patients actually visited a hepatology clinic.

The median age in the overall patient cohort was 54, and 53.2% (432) were women. Ultrasound was done to evaluate “elevated liver enzymes” in 28.2% of patients, to evaluate abdominal l pain in 13.7%, and 58.1% were scanned for reasons unrelated to hepatobiliary concerns. Most scans were ordered by primary care providers. Type 2 diabetes was present in 23.2% of patients, 43.3% had normal alanine transaminase (ALT) and the other 56.7% had elevated ALT levels.

A total of 69.2% (512) of patients had hepatic steatosis acknowledged by the ordering provider, and 29.0% (236) of those patients were actually seen by a hepatologist. Those with ALT were more likely to be referred than those whose liver enzymes were normal. A lower percentage of patients with diabetes were seen by a hematologist than those without diabetes (19.7% vs. 24.9%, respectively).

Patients who had an ultrasound ordered to evaluate elevated liver enzymes or those under suspicion for liver disease made up approximately half (47.0%) of patients seen by hepatologists. Those whose primary care provider or gastroenterologist ordered the ultrasound were more likely to be seen by a hepatologist.

Of the patients evaluated at a hepatology clinic, 53.0% (126) underwent staging via transient elastography, magnetic resonance elastography, and/or liver biopsy. Stage F2 or higher (clinically significant based on risk of liver morbidity and mortality) fibrosis was present in 23 of those patients (18.2%). Diabetes had a strong correlation with clinically significant fibrosis, as did low platelets. Elevated ALT, high low-density lipoprotein cholesterol and triglycerides were not correlated with clinically significant fibrosis in the study cohort. A total of 90.0% of patients who had acknowledged hepatic steatosis were overweight or obese, but high body mass index was not correlated with hepatology referral.

Overall, the study supports radiological intervention to increase provider awareness of hepatic steatosis on ultrasounds.

“Based on these findings, incidental identification of fatty liver on ultrasound is a critical opportunity for diagnosis and downstream disease management,” the authors wrote, “however, there is room to improve our pathways for evaluation and specialty care.”

Study limitations included the fact that for some patients, although there was no prior diagnosis of fatty liver or liver disease assessment, an ultrasound ordered for elevated liver enzymes may have led to expected findings. And despite efforts to weed out any patients who had secondary causes of fatty liver such as alcohol or other chronic liver conditions, some patients may have slipped through. And because the study was single center with a mostly White cohort, the results may not be generalizable.

Reference

Nagra N, Penna R, La Selva D, Coy D, et al. Tagging incidental finding of fatty liver on ultrasound: A novel intervention to improve early detection of liver fibrosis. J Clin Transl Res. Published online September 29, 2021. doi:10.1016/j.jacr.2021.04.017