One field within the specialty of gastroenterology that has witnessed rapid changes over the last two decades is hepatology. Over the past 20 years, there have been significant advances to the understanding of many liver diseases and rapid evolution of therapies.
These advancements have been recognized by the gastroenterology societies and the American Board of Internal Medicine (ABIM). As a result, a separate ACGME certified training pathway was created to be added onto to general GI fellowship.
This Advanced/Transplant Hepatology fourth year fellowship became mandatory in 2010. Since then some trainees are allowed to complete the Advanced/Transplant Hepatology training within the three-year â€œfast-trackedâ€ general GI fellowship.
The ABIM first offered separate board certification within gastroenterology to self-identified hepatologists in 2006. The transplant hepatology exam is now offered every two years, and about 90 new physicians choose this board certification path each exam cycle.1
Despite the standardization in training and certification, there remains a national shortage of certified hepatologists to meet the growing patient need. At the same time, the epidemiology of various liver disease has evolved over the last 20 years. The reasons are multifactorial and depend on the disease state.
The most rapid changes over the last decade relate to hepatitis C. The introduction in 2011 of the first direct-acting agents (DAAs) have revolutionized the management of this infectious disease. The first-generation drugs were quickly followed by all oral DAA therapies with higher cure rates and minimal side effects.
Today, patients with chronic hepatitis C will expect to have cure rates of more than 98 percent with initial course of therapy. Much higher rates can be achieved with salvage therapies. These newer therapies are so effective that the World Health Organization has made it a mission to eradicate hepatitis C worldwide by 2030.
Of course, this effort requires identification of all patients infected and mitigating new infections from high-risk populations. There remains an estimated 2-3 million untreated Americans with chronic hepatitis C. Seventy-five percent of these infections remain in the baby boomer birth cohort (1945-1965).
However, the most common source for new infections is linked to the opioid epidemic from people injecting drugs. This highlights the need for ongoing multidisciplinary activities to curb opioid abuse and increase programs that help to reduce harm in these at-risk populations.
Alcohol liver disease
Many of you are aware that problematic alcohol use is on the rise in the U.S. Alcoholic liver disease (ALD) is a leading cause of mortality in the United States, with nearly 250,000 deaths attributed to ALD in 2010.2,3 The prevalence of ALD has remained stable, affecting about 4.7 percent of adults in 2015-2016 as determined from the NHANES database.4
However, the prevalence of ALD with advanced liver fibrosis has been increasing. This is concerning given that fibrosis is the strongest predictor of progression to cirrhosis, liver cancer and death.
Among patients with end-stage liver disease, ALD became the leading indication for U.S. liver transplants in 2016, finally surpassing hepatitis C. A U.S. population-based study demonstrated increasing cirrhosis death rates largely driven by alcoholic cirrhosis, particularly among young individuals aged 25 to 34 years.5 These trends are consistent with what we are seeing at our own liver transplant center.
Non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease (NAFLD), which encompasses both fatty liver and non-alcoholic steatohepatitis (NASH) â€” fatty liver with inflammation and liver fibrosis â€” is becoming more prevalent. NAFLD has a global prevalence of about 25 percent and is pushing towards 30 percent to 50 percent in the U.S.
It is now the second most common cause for liver transplant and expected to become the leading etiology in the near future. This has coincided in the U.S. with the obesity epidemic.
NAFLD tends to cause liver fibrosis more slowly than alcoholic liver disease, and as a result patients tend to be older when they develop cirrhosis and its complications. It is known that diet and exercise, with weight loss of at least 10-20 pounds, can lead to metabolic improvements and improvements in liver histology, including the regression of liver fibrosis.
However, weight loss is hard to maintain for many patients. There are currently many promising drug targets in phase 2 and 3 clinical trials, and therapies aimed at improving NASH with fibrosis may be commercially available in the U.S. as soon as 2020.
It is an exciting time to practice hepatology. There are many advancements recently achieved and many more forthcoming to help manage the diseases for many of these complex patients. Please stay tuned.
2. Rehm J, Samokhvalov AV, Shield KD. Global burden of alcoholic liver diseases. J Hepatol. 2013;59(1):160-168
3. Tapper EB, Parikh ND. Mortality due to cirrhosis and liver cancer in the United States, 1999-2016: observational study. BMJ. 2018;362
4. Ashwani K, Singal MD, et al. Prevalence of Alcoholic Fatty Liver Disease Among Adults in the United States, 2001-2016. JAMA: 2019;321(17):1723-1725
5. Cholankeril G, Ahmed A. Alcoholic liver disease replaces hepatitis C virus infection as the leading indication for liver transplantation in the United States. Clin Gastroenterol Hepatol. 2018;16(8):1356-1358.