Chronic liver disease is caused by repeated insults to the liver, which can result in inflammation, fibrosis and ultimately cirrhosis.
Chronic liver disease (CLD) is the result of repeated damage to the liver by a variety of aetiological factors including alcohol, toxins, viruses and many others. CLD is generally defined as progressive liver dysfunction for six months or longer. The end result of chronic liver disease is cirrhosis, which describes irreversible liver remodelling.
The liver is involved in numerous functions that are essential to maintain the bodies homeostasis. To appreciate the sequelae of CLD we must understand the normal role of the liver in human health.
CLD represents the fourth commonest cause of years of life lost in those aged under 75. It is the only major chronic condition with an increasing death rate.
The true prevalence is difficulty to quantify as the majority of CLD is asymptomatic and presents late. However, in England and Wales an estimated 600,000 patients have CLD. There has been a significant increase in hospital admissions relating to cirrhosis over the last two decades.
Chronic liver disease can arise due to a wide range of pathologies.
Progressive liver injury culminates in cirrhosis, which describes irreversible liver remodelling.
Overtime, progressive insults to the liver leads to inflammation (hepatitis), fatty deposits (steatosis) and scarring (fibrosis). The normal liver architecture is replaced by fibrotic tissue and regenerative nodules.
The end result of this process is cirrhosis, which describes irreversible liver remodelling that is associated with significant morbidity and mortality. Cirrhosis is often used synonymously with end-stage liver disease or advanced liver disease.
NOTE: Cirrhosis usually develops over many years and presents late. This means cirrhosis could be prevented through earlier detection and treatment. In fact, it is estimated that over 90% of liver disease is preventable.
The severity of cirrhosis can be graded using the Child-Pugh score.
The Child-Pugh (CP) classification is based on the clinical and biochemical features of decompensated cirrhosis.
The CP score was originally created as a prognostic tool for patients undergoing surgery for oesophageal varices. It has also been used to assess risk of mortality following abdominal surgery. For example, one review showed a 10% mortality among Child-Pugh A cirrhosis compared to 82% for those with Child-Pugh C cirrhosis.
The different classes reflect the severity of cirrhosis and provide an estimated one year survival.
Classical stigmata of CLD include spider naevi, palmar erythema, jaundice, hair loss, leuconychia, asterixis, ascites.
Early clinical features are usually non-specific. They include anorexia, lethargy, weight loss, hepatomegaly, nausea or disturbed sleep pattern.
As patients develop more advanced disease, typical features develop. These clinical features are collectively referred to as ‘stigmata of chronic liver disease’. Among these, jaundice, ascites and encephalopathy are all features of decompensated cirrhosis.
Liver biopsy is still considered the gold-standard diagnostic method for the identification of cirrhosis.
During the diagnostic work-up, it is important to confirm both the presence of cirrhosis and the underlying aetiology (see 'non-invasive liver screen').
For the diagnosis of cirrhosis, a combination of biochemical tests, non-invasive techniques, imaging and liver biopsy are used. Liver biopsy is considered the gold standard, however, it is invasive and associated with complications. Therefore, alternative investigations are used where possible.
Laboratory tests including liver function tests (LFTs), cannot be used to exclude cirrhosis. Less than 1 in 20 patients with asymptomatic cirrhosis will have an elevated transaminase (ALT/AST). However, they can be used to support the diagnosis of cirrhosis.
Biochemical test may show subtle changes in cirrhosis such as AST/ALT ratio, AST/platelet ratio or thrombocytopenia (i.e. indicative of portal hypertension and hypersplenism).
In decompensated cirrhosis significant abnormalities may be seen (e.g. deranged LFTs, hyperbilirubinaemia, raised INR, low albumin).
A quick painless test that assesses liver stiffness. It measures sound wave velocity using an ultrasound probe to indicate the ‘degree’ of fibrosis and thus likelihood of cirrhosis.
A liver biopsy can be performed percutaneously using US or CT-guidance, or transjugular. A transjugular biopsy approaches the liver via the hepatic vein. It is completed if contraindications to percutaneous liver biopsy are present (e.g. ascites, coagulopathy).
Liver biopsies are usually reserved for specific cases:
Due to the wide number of pathologies a ‘non-invasive liver screen’ is often used to determine the aetiology.
A non-invasive liver screen refers to screening questions, biochemical tests and imaging to assess patients with suspected liver disease. It is employed when blood tests show abnormal liver function or CLD is suggested from clinical examination/imaging.
Management involves treating the underlying pathology, preventing progression and managing complications.
The key strategy in managing patients with CLD is removing the aetiological factor leading to progressive liver damage. This may be a simple intervention like alcohol cessation, removal of offending medications or use of anti-viral therapies in chronic hepatitis.
Unfortunately, many conditions do not have a therapeutic option and there are limited interventions available to prevent the overall progression of CLD. Therefore, many strategies are focused on targeting key pathogenic events that occur in cirrhosis and on managing complications. The principle of management of the main complications of cirrhosis are discussed below.
Hepatic encephalopathy describes neuropsychiatric disturbances in the context of CLD.
It is thought to occur because the liver is unable to clear harmful substances that are produced by bacteria within the gastrointestinal tract (i.e. ammonia). Constipation is a main driver of encephalopathy.
Ascites describes fluid accumulation within the peritoneal cavity.
It develops due to a combination of portal hypertension and loss of oncotic pressure (hypoalbuminaemia). Due to widespread vasodilatation and underperfusion, the renin-angiotension-aldosterone systems (RAAS) is active leading to excess water and sodium reabsorption that exacerbates ascites.
Oesophageal varices occur secondary to portal hypertension.
Cirrhosis leads to the development of portal hypertension because of extensive scarring and increased pressure through the portal system. Consequently, blood is shunted into the systemic circulation at porto-systemic sites. At the lower oesophagus this leads to dilated, tortuous vessels known as varices that are at high-risk of bleeding.
SBP refers to infection within ascitic fluid.
SBP is a serious medical condition with a high mortality. It is defined as a predominantly neutrophilic ascitic white cell count (WCC) >250/mm3.
Patients with cirrhosis or chronic hepatitis B are high-risk of developing hepatocellular carcinoma. They should be invited to undergo six monthly surveillance with ultrasound +/- AFP.
Liver transplantation is potentially a life-saving treatment for patients with chronic liver disease or associated complications.
Within the UK, patients deemed suitable for transplantation undergo formal assessment that reviews both their indications and contraindications to transplant. Current criteria for selection is based on the United Kingdom model for end-stage liver disease (UKELD) score, which is an adaptation of the original model for end-stage liver disease (MELD) score.
The UKELD is based on serum creatinine, sodium, bilirubin and INR. The minimum criteria for listing a patient for liver transplantation is a score ≥ 49, which represents a 9% one year mortality without transplant. Other indications for liver transplantation, outside the UKELD score, are based on the presence of hepatocellular carcinoma with specific criteria and variant syndromes (e.g. diuretic resistant ascites).
Cirrhosis is associated with significant morbidity and mortality from a number of complex, interlinked, complications.
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