Primary care AST-testing for chronic liver disease detection

Chronic liver disease is on the rise. Aside from undetected liver disease, abnormal liver function tests are often not followed up in primary care, or many patients ignore their follow-up appointments.

A study involving almost 18,000 patients has led to a significant increase in cirrhosis diagnosis

The incidence and mortality of chronic liver disease in the general population is on the rise. Aside from undetected liver disease, abnormal liver function tests are often not followed up in primary care, or many patients ignore their follow-up appointments.

The incidence and mortality of chronic liver disease in the general population continues to rise. In addition to undetected liver disease, one of the problems is that abnormal liver function tests are often not followed up in primary care, and when they are, many patients do not attend their appointments. Dr. Andrew Yeoman, from the Aneurin Bevan University Health Board’s  Hepatology section in Newport, UK, showed how this can be changed through targeted testing through the Gwent AST Project (GAP) during the EASL 2020 ILC digital congress. The pilot project, launched in 2016, investigates whether the diagnosis of significant liver disease can be improved by using aspartate aminotransferase (AST) tests in the context of elevated alanine Aminotransferase (ALT) levels. Dr. Yeoman provided an update on the 2-year experience of this project.

AST is an enzyme found in various organs of the body, including the heart, liver, and muscles. When the liver is damaged, AST can be released into the bloodstream. A high score on an AST test can indicate a problem with the liver or muscles. Because AST levels are not as specific for liver damage as ALT, they are usually measured together with ALT to check for liver problems.

In the GAP project, the automatic measurement of AST serum was carried out in primary care patients in whom elevated ALT levels had been detected. The AST:ALT ratio was also evaluated. Dr. Yeoman developed an algorithm based on a combination of the AST:ALT ratio, ALT concentration, and relevant underlying diagnoses such as excessive alcohol consumption, obesity, and metabolic syndrome, to serve as a guide for further investigation and treatment. Patients with a ratio ≥1 are considered to be at increased risk of developing significant liver disease, regardless of the extent to which their ALT is elevated, while patients with a ratio <1 have a low risk.

81% increase in the number of diagnosed cirrhosis cases

17,770 people showed increased ALT. Of these, 2,117 (12%) had an AST:ALT ratio >1. Also, 750 of these patients were referred from primary care to a specialist while 348 were subjected to a FibroScan examination (also known as transient elastography). A significant number of patients (about 40%) did not attend a FibroScan appointment. Among the patients who underwent a FibroScan, 43% had a reading <8 kPa, 28% 8-15 kPa and 29% >15 kPa.

The most common cause of liver disease was non-alcoholic fatty liver (NAFLD) in 49% of cases and alcoholic fatty liver in 40%. A total of 192 cases of advanced fibrosis were identified in this way. Since the tests were introduced, there has been an 81% increase in the number of cases of cirrhosis diagnosis. In addition, a further 33 patients who were not originally referred were subsequently diagnosed with liver disease (28 with cirrhosis or hepatocellular carcinoma, also known as HCC).

General practitioners are still less involved in the strategy

The introduction of the reflex AST test and the calculation of the AST:ALT ratio in primary care has led to a significant increase in the diagnosis of cirrhosis.  As Dr. Yeoman made clear, the introduction of reflex AST testing in primary care is simple and population-based. The tests generate increased but manageable demand for FibroScan. It significantly increases the number of diagnoses and thus improves the detection of cirrhosis.

However, a strong focus should be placed on education and the support of primary care, as general practitioners, in particular, have not yet participated enough in such a strategy. Both adherence to referral channels by general practitioners and community access to non-invasive fibrosis testing needs to be improved to increase the detection rates of advanced liver disease. Dr. Yeoman also stressed that the detection of cirrhosis is a process, not a single event.

As challenges for the future, Dr. Yeoman mentioned that the project should be expanded on a nation-wide basis. He also suggested improving compliance by general practitioners and understanding the reasons for not being referred to a specialist. The AST:ALT thresholds for referrals should also be reviewed.

References:
EASL The Digital international Liver Congress, 27 to 29 August 2020 General hepatology, abstract session, Session 13:00-15:00 Hours ECT

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