The Role of Liver Biopsy in Hepatitis C

KEY POINTS

• Serum-based tests are precise and unequivocal, and a positive HCV RNA test confirms HCV infection.
• In the absence of clinical or laboratory findings suggesting a second liver pathology, a liver biopsy will not alter the diagnosis.
• Liver biopsy provides useful information about the degree of fibrosis in HCV-infected patients. This information is important for making decisions in the management of HCV infection.
• Abstinence from alcohol is recommended for those infected with HCV. The effect of mild to moderate alcohol use on liver disease progression in HCV infection is controversial. Mild to moderate alcohol use outside the context of therapy may not be associated with fibrosis.
  

Liver biopsy plays a central role in the evaluation of chronic liver diseases, including HCV infection. In 1997, a National Institutes of Health (NIH) Consensus Development Conference Panel endorsed liver biopsy prior to the initiation of treatment of HCV infection.²¹ In 2002, another NIH consensus conference noted:

"Liver biopsy provides a unique source of information on fibrosis and assessment of histology. Liver enzymes have shown little value in predicting fibrosis. Extracellular matrix tests can predict severe stages of fibrosis but cannot consistently classify intermediate stages of fibrosis. Moreover, only liver biopsy provides information on possible contribution of iron, steatosis, and concurrent alcoholic liver disease to the progression of chronic hepatitis toward cirrhosis. . . . Thus, the liver biopsy is a useful part of the informed consent process. . . . Since a favorable response to current antiviral therapy occurs in 80% of patients with genotype 2 or 3, it may not always be necessary to perform liver biopsy in these patients." ²²

The histologic features of chronic HCV infection are well defined. Two components are considered: activity and fibrosis.

Activity. Activity is gauged by the number of mononuclear inflammatory cells present in and around the portal areas, and by the number of dead or dying hepatocytes. Changes in activity do not imply progressive disease.

Fibrosis. The fibrotic response to HCV infection is variable. Fibrosis implies possible progression to cirrhosis. In mild cases, fibrosis is limited to the portal and periportal areas. More advanced changes are defined by fibrosis that extends from one portal area to another. The term for this is "bridging fibrosis". In some, this reaction evolves into cirrhosis.

Other histologic changes, such as macrovesicular fat (steatosis),²³ may be seen, but they are not particularly useful. A standardized evaluation of liver histology in HCV infection is helpful, and several means have been developed and validated. Each considers the degree of liver pathology from the standpoint of the amount of inflammation and the amount of fibrosis (Table 6).

Table 6
Three common histologic grading and staging scales in HCV infection
	Necroinflammation	Fibrosis	Total Score
Histology Activity Index (HAI)24	0 to 18	0 to 4	0 to 22
Ishak Modified HAI25	0 to 18	0 to 6	0 to 24
METAVIR26	0 to 3	0 to 4	0 to 7

Fibrosis, more than inflammation, predicts the progression to irreversible liver disease in HCV infection. The METAVIR system is simple and easy to learn, and it has been extensively validated (Table 7).²⁷

Table 7
METAVIR fibrosis grading scale
Finding	Score
No fibrosis	0
Portal fibrosis	1
Bridging fibrosis, slight	2
Bridging fibrosis, marked	3
Cirrhosis	4

For all its advantages, liver biopsy has several important disadvantages. Among them are cost, the risk of complications, the need for additional health care resources, patient and physician aversion to the procedure, inadequate specimen size, and the lack of specific findings.

Cost. Liver biopsy adds between U.S. $1,500 and U.S. $2,000 to the cost of an evaluation.

Complications. Approximately 20% to 50% of patients will experience significant pain following percutaneous liver biopsy. More severe complications—such as pneumothorax, major bleeding, inadvertent biopsy of the kidney or colon, and perforation of the gallbladder—have been reported in a fraction of patients (0.57%). There have even been a few reports of death.^28,29

Resources. In most cases, liver biopsy requires the involvement of a physician (usually a gastroenterologist or radiologist) who may not be the treating physician.

Patient aversion. Patients find liver biopsy anxiety provoking, even when the procedure goes well. Some specialists now advise premedication with anxiolytic agents to reduce apprehension—for example, midazolam, 1 to 2 mg IV, or lorazepam, 1 mg po, before the procedure. Some use meperidine, 12.5 to 25 mg IV, before biopsy to improve comfort. Additional narcotic analgesia may be necessary if post-biopsy pain is more than mild.

Physician aversion. A recent survey of 112 gastroenterologists in the southeastern United States revealed that between one-quarter and one-third do not perform liver biopsies because they are concerned about complications and low reimbursement.³⁰ These respondents said they refer patients to a radiologist for liver biopsy. More than three-quarters (77%) routinely biopsy all HCV-infected patients before treatment, and the others biopsy selected HCV-infected patients to assist in decision-making. Only 3.6% do not biopsy any patients before treatment. Post-treatment biopsies are performed much less frequently. Seven percent of the surveyed physicians routinely biopsy all patients after treatment. Ultrasonography is used as a guide to biopsy selection site by nearly one-half (47%), although it is used by only 5% when the biopsy is performed by the gastroenterologist.

A recent observational study of 166 HIV/HCV-coinfected injection-drug users in France found that 45% underwent liver biopsy during a 5-year follow-up period; factors predictive of liver biopsy were high social support, complete abstinence from drugs, lack of immunosuppression, male gender, lack of multiple incarcerations, recent onset of drug use, and increased liver enzyme levels.³¹

Specimen size. The amount of liver tissue obtained by needle biopsy represents no more than 1/30,000 of the liver volume. It is apparent that such a small sample will only represent the state of the liver for processes that are uniformly distributed. Several studies indicate that fibrosis may not be uniformly represented in each biopsy specimen. Postmortem studies in cirrhotics indicate that known cirrhosis will often be absent in a single core of liver tissue and that up to three specimens may be needed.^32,33

A recent study of "virtual biopsy specimens" confirmed that the amount of liver tissue available for the pathologist to review is critical.³⁴ A biopsy length of 15 mm was 65% accurate in scoring the degree of fibrosis; a biopsy length of 25 mm was 75% accurate. Specimens longer than 15 mm that contain six or more portal areas correlate better with biochemical surrogate markers of fibrosis than do smaller specimens.³⁵

Most studies have ignored the impact of the width of the biopsy specimen. Colloredo et al have shown that the use of fine needles (internal diameter; 1 mm) impedes accurate staging of fibrosis, probably because of the decreased number of portal areas available in such specimens.³⁶ Similarly, in a study of 149 paired liver biopsy specimens, Brunetti et al concluded that fine-needle biopsy had unsatisfactory discriminant ability and systematically underscored histologic variables compared with coarse-needle biopsy.³⁷ Thus, both the length and the width of the biopsy specimen have been shown to be important in reducing diagnostic error. Many have suggested that five to eleven portal areas should be included before the pathologist can stage HCV-infected livers accurately. A single core of liver tissue obtained with a "biopsy gun" with a needle notch length of 1.7 cm may be expected to result in significant under-reporting of fibrosis. Scheuer recently published an excellent summary of this issue.³⁸

Lack of specific findings. All histologic abnormalities in HCV infection—individually and collectively—are seen in other viral and nonviral liver diseases. Even interpretation of fibrosis requires caution. A previous heavy user of alcohol, abstinent for several months prior to liver biopsy, may have significant hepatic fibrosis. Without concurrent changes of steatohepatitis, the fibrosis might be erroneously ascribed to HCV when, in fact, alcohol may have been more important in the activation of stellate cells and consequent fibrosis.

The utility of liver biopsy in routine cases of HCV infection has been challenged on the basis that clinical and laboratory parameters alone provide sufficient information to make a decision for or against antiviral therapy.³⁹ Liver biopsy is not necessary to establish the diagnosis of HCV infection. Serum-based tests are precise and unequivocal, and a positive HCV RNA test confirms infection. In the absence of other clinical or laboratory findings suggesting the possibility of a second liver pathology, a liver biopsy will not alter the diagnosis. A study at the Cleveland Clinic found that no case of HCV infection diagnosed by serum-based tests was overturned by liver biopsy findings.⁴⁰ Moreover, in only 2% of cases was an additional liver diagnosis made.

Cirrhosis is found in approximately 29% of unselected cases of HCV infection that come to biopsy.⁴⁰ Clinical and laboratory tests are relatively weak predictors of the extent of liver damage caused by HCV infection. The number of HCV-infected patients whose liver disease staging (either advanced fibrosis or, conversely, no fibrosis) can be confidently predicted by the AST:ALT ratio, the international normalized ratio (INR), and the platelet count is low. A published cirrhotic discriminant score (Bonacini) for the clinical diagnosis of cirrhosis correctly established or excluded a diagnosis of cirrhosis in only 23% of cases.⁴⁰ In the remainder, liver biopsy was critical for proper staging. These findings have recently been confirmed by other groups.^39,41 Others have also found that predicting severe cirrhosis or fibrosis on the basis of laboratory tests (eg, AST:ALT ratio, platelet counts, and measurements of hyaluronic acid, fibronectin, pseudocholinesterase levels, etc) is not sufficiently sensitive.⁴²

Recently, new attempts to stage hepatitis C according to serum-based indices have been offered. Investigators have suggested that biochemical markers of liver fibrosis in patients with HCV infection allow for satisfactory staging of disease in many, if not most, HCV-infected patients.⁴³ The fibrotest has been used to assess the histologic effects of antiviral therapy.³⁵ Table 8 lists those markers that have been combined in various ways to detect fibrosis.

Table 8
Indirect assessment of cirrhosis
Traditional	Non-traditional
Markers of hypersplenism      WBC, platelets, Hgb	AST:ALT ratio
Markers of portal hypertension      Ascites, varices, portosystemic      encephalopathy
Imaging features	AST:platelet ratio
Surgical view	Haptoglobin
	Gamma glutamyl transpeptidase
	Gamma globulin
	Bilirubin
	Apolipoprotein
	Hyaluronidase
	Pseudocholinesterase
	Manganese superoxide dismutase
	N-acetyl-ß-galactosidase
	Procollagen III nucleoprotein
	Type IV collagen
	TIMP-1
	YKL-40
	Laminin

Although the calculated fibrosis score rises with increasing degrees of histologic fibrosis, the overlap in serum-based scores in different histologic METAVIR grades limits the clinical utility of this approach (Figure 3).

Others have proposed a simpler model,⁴⁴ based on an AST:platelet ratio index calculated as follows:

AST:platelet ratio index = [(AST/ULN)/platelet count] X 100

where the platelet count is expressed as 10⁹/L and ULN stands for upper limit of normal. This index, if properly validated, may be clinically useful.

The need for liver biopsy in HCV infection should be predicated on the type of information that is being sought for an individual patient. The presence or absence of cirrhosis is clinically relevant in many cases where therapy with antivirals is being considered. All other features being constant, the presence of bridging fibrosis or cirrhosis markedly reduces the expected response rate to antiviral therapy. Major shifts in expected outcomes are far from trivial and will often alter the clinical decision to treat.⁴⁵ In addition to identifying a lesser chance of successful viral elimination, the goal of prevention of cirrhosis becomes moot if cirrhosis is present on pretreatment biopsy. Additional management changes often mandated by finding cirrhosis include entry into surveillance programs for hepatocellular carcinoma and for esophageal varices.

Liver biopsy remains an important tool in the baseline evaluation of the HCV-infected patient. A specimen of sufficient length (15 mm) and width (1.4 mm) that contains at least six portal areas is desired. How frequently sequential biopsies should be performed in the HCV-infected patient, if at all, has not been established. There appears to be little need for routine biopsies following a course of antiviral therapy. Authorities differ in clinical practice with respect to follow-up biopsies at various intervals to restage the liver in HCV infection. We do not recommend routine follow-up biopsies.