Fibrosis in Chronic Liver Disease
When the liver is injured, it responds by forming scar tissue, also known as fibrosis. As the fibrosis advances it can result in cirrhosis of the liver. In end-stage cirrhosis, the liver becomes hard and can no longer effectively replace damaged cells. This leads to serious life threatening complications, including portal hypertension, liver failure and liver cancer. Cirrhosis and liver cancer are now among the top ten causes of death worldwide.
Liver fibrosis can be caused by all chronic liver diseases (CLDs). Until the 1990’s, the main CLDs were chronic viral hepatitis B and alcoholic liver disease. Recently, others have become prominent in the etiology of CLD. Chronic hepatitis C (CHC) and non-alcoholic fatty liver disease (NAFLD) have had a major impact on CLD incidence. NAFLD is considered to be a major cause of fibrosis.
NAFLD is the buildup of extra fat in the liver not caused by alcohol consumption. Normal livers contain some fat. If more than 5%-10% of the liver’s weight is fat, then the patient is considered to have fatty liver disease. Obesity, a major cause of NAFLD, is increasing in the developed world. In the past 10 years, the rate of obesity has doubled in adults and tripled in children. The US prevalence of overweight adults has risen to more than 65%. Of these 30% are considered obese.
The overall prevalence rates for CLD in the United States increased from 12% in the late early 1990’s to 15% in the mid 2000’s. The prevalence of diagnosed NAFLD almost doubled in the same time frame going from 5.5% to 11%. NAFLD accounted for 47% of CLD in the late 1990’s and rose to 75% in the mid 2000’s. However, estimates are that one-third of the general population in the US has some form of NAFLD and approximately 20% of those will develop significant fibrosis.
A more severe form of NAFLD is non-alcoholic steatohepatitis (NASH). NASH causes the liver to swell and become damaged. Diabetes, high cholesterol and high triglycerides as well as obesity are risk factors for NASH.
The prevalence of NASH is more difficult to determine. It is estimated to occur in approximately 3% of the population but may be found in more than 25% of obese persons. NASH often has no symptoms. NASH is one of the leading causes of cirrhosis in adults in the United States. Up to 25% of adults with NASH may have cirrhosis.
A liver biopsy is the most accurate test for liver disease. But because it’s less invasive, liver ultrasonography is the technique most commonly used to diagnose NAFLD in the general population. However, it is known to underestimate the prevalence of the disease. Liver enzymes have not proved to be very useful in the diagnosis of NAFLD.
Viral Diseases – Chronic hepatitis B & C
The main goal of treatment of chronic hepatitis B & C is to suppress viral replication and to induce remission of liver disease before development of cirrhosis and liver cancer. Interferon alpha and antiviral drugs are used for hepatitis B.
In hepatitis C, if blood tests and a liver biopsy do not show damage to the patient’s liver, treatment may not be needed. However, patients that are not treated may need liver biopsies every few years to check for damage in their liver. When treatment is necessary, a combination of interferon combined with ribavirin and a protease inhibitor is used for 6 months to a year to help the patient’s body clear the virus. Newer, simpler regimens are in clinical trials.
Alcoholic Liver Disease
Liver disease caused by alcohol is treated by avoiding alcohol, eating a healthy diet and often participating in an alcohol recovery program. Medications may be needed to manage the complications caused by your liver damage. A liver transplant may be needed in more advanced cases of alcoholic cirrhosis.
NAFLD & NASH
There are no current medical treatments for NAFLD. Patients with NAFLD are told to lose weight, control cholesterol and triglycerides, eat a heathy diet, avoid alcohol and control diabetes if it is present.
Approximately 5,000–6,000 patients in the US with end stage liver disease receive liver transplants each year. The 1-year, 3-year and 5-year survival rates are 87%, 78% and 73% respectively. The American Association for the Study of Liver Diseases (AASLD) and the Trust for America's Health (TFAH) issued a report in 2010 stating that the first year cost for a liver transplant could be greater than $267,000. From 2001 to 2009, 35,781 patients underwent a primary liver transplant, including 1,959 for whom NASH was the primary or secondary indication. NASH is now the third most common indication for liver transplantation in the United States.