SEARCH

SEARCH BY CITATION

Abstract

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. References

Liver tissue alterations other than fibrosis may have an impact on liver stiffness measurement. In this study we evaluated 18 patients without a previous clinical history of liver disease, consecutively admitted for acute viral hepatitis. In each patient, aminotransferase determination and liver stiffness measurement were performed on the same study day, at 3 different points: (1) peak increase in aminotransferase; (2) aminotransferase 50% or less of the peak; (3) aminotransferase levels ≤2× the upper limit of normal. In all patients, the degree of liver stiffness at the time of the peak increase in aminotransferases exceeded the cutoff values proposed for the prediction of significant fibrosis or cirrhosis. A progressive significant reduction in liver stiffness values was observed (P < 0.0001) in the follow-up period in parallel with the reduction of aminotransferase levels (P < 0.0001). Moreover, a statistically significant, positive correlation between aminotransferases and liver stiffness measurement (LSM) at the onset of acute viral hepatitis was found (r = 0.53, P = 0.02 and r = 0.51, P = 0.03 for alanine aminotransferase and aspartate aminotransferase, respectively). In conclusion, the extent of necroinflammatory activity needs to be carefully considered in future studies aimed at further validating transient elastography, particularly in patients with absent or low-stage liver fibrosis (in other words, F0-F2 METAVIR). LSM does not represent a reliable instrument to detect the presence of advanced fibrosis and cirrhosis in patients presenting with a clinical picture of acute hepatitis. (HEPATOLOGY 2007.)

Transient elastography has been proposed as a rapid and noninvasive technique for the evaluation of disease progression in chronic liver diseases (CLD). This is based on the assumption that liver stiffness is a function of the fibrotic transformation of liver tissue typical of CLD and leading to cirrhosis.1 Accordingly, the results of recent cohort studies have suggested that the degree of fibrotic evolution of the disease could be predicted by applying different cutoff values of liver stiffness.2–4 Although the accumulation of fibrillar extracellular matrix is certainly a major determinant of liver tissue stiffness, it is possible that other features of CLD, that is, inflammatory infiltration, tissue necrosis, or edema, influence this parameter. This possibility is raised by the observation that in patients with CLD of different causes, liver stiffness shows a trend to increase in parallel with the degree of necroinflammatory activity,5 and it is corroborated by a recent report showing significant variations in liver stiffness during alanine aminotransferase (ALT) flares in patients with chronic viral hepatitis.6 Therefore, the degree of fibrosis evaluated by transient elastography could be overestimated in the presence of hepatitis exacerbations.

To definitively assess the influence of necro-inflammation on liver stiffness measurement (LSM), we designed a study in which LSM was performed during the course of acute viral hepatitis, from the clinical onset to resolution, in patients without a previous clinical history of liver disease.

Patients and Methods

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. References

Patients.

The study included 18 consecutive patients (10 men and 8 women, mean age 40.9 ± 16.3; age range 16-75 years) admitted to Department of Infectious Diseases of the Azienda Ospedaliero Universitaria Careggi—Florence, between October 1, 2006 and March 1, 2007, with acute viral hepatitis. The diagnosis was based on the positivity of hepatitis A virus, hepatitis B virus, or hepatitis C virus markers and an increase in aminotransferase level higher than 10-fold the upper limit of normal (ULN). On the same day of diagnosis, all patients were referred to the ultrasonographic laboratory of our institution and subjected to LSM and complete upper abdomen ultrasonography examination. Exclusion criteria were a body mass index of 30 or greater, the presence of ascites at clinical or ultrasound examinations, diagnosis of previous chronic liver disease suspected on the basis of standard clinical, ultrasonographic,7–10 or biochemical parameters obtained within 6 months before the onset of acute hepatitis (available in 11 of 18 subjects), a platelet count less than 140 × 109/L,11 co-infection with human immunodeficiency virus, intravenous drug use, alcohol abuse or the use of hepatotoxic drugs within the 6 months preceding the study, metabolic liver disease, autoimmune hepatitis, vascular diseases of the liver, and biliary tract disorders, cardiac failure, or pregnancy. In each patient, aminotransferase determination and LSM were performed on the same day, at 3 different time points: (1) peak increase in aminotransferase (corresponding for all patients to the day of diagnosis); (2) aminotransferase 50% or less of the peak; (3) aminotransferase levels ≤ 2 ULN. Laboratory tests, including serum bilirubin, albumin, ammonia, aminotransferases (aspartate aminotransferase [AST], ALT) levels, alkaline phosphatases, gamma glutamyl-transpeptidase, international normalized ratio, platelet count, creatinine, and glucose, were performed in all patients at the time of enrollment and were followed up until resolution. The study protocol was approved by the Investigation and Ethics Committee of the Azienda Ospedaliero Universitaria Careggi, Firenze. The nature of the study was explained to the patients, each of whom provided written informed consent before the beginning of the study, in accordance with the principles of the Declaration of Helsinki (revision of Edinburgh, 2000).

Transient Elastography.

After an overnight fasting, patients underwent a complete upper abdomen ultrasound examination. Immediately after, transient elastography was performed using the FibroScan apparatus (Echosens, Paris, France), which consists of a 5-MHz ultrasound transducer probe mounted on the axis of a vibrator. Mild amplitude and low-frequency vibrations (50 Hz) are transmitted to the liver tissue, inducing an elastic shear wave that propagates through the underlying liver tissue. The velocity of the wave is directly related to tissue stiffness. The tip of the transducer was covered with a drop of gel and placed perpendicularly in the intercostal space with the patient lying in dorsal decubitus with the right arm in the maximal abduction. Under control time motion (TM) and A-mode, the operator chose a liver portion within the right liver lobe at least 6 cm thick, free of large vascular structures and gallbladder.2, 3 Stiffness was measured on a cylinder of hepatic tissue of 1 cm diameter and 2 to 4 cm length. The operator was a staff physician (U.A.) who had previously performed at least 100 determinations in patients with CLD. The median value of 10 successful acquisitions, expressed in kilopascal (kPa), was kept as representative of the LSM. As previously described3, 12 and as suggested by the provider of the instrumentation, we considered representative measurements 10 successful acquisitions with a success rate of at least 60%, and with an interquartile range lower than 10%.

Statistical Analysis.

Statistical analysis was performed using the Stata Statistical Software Release 9.0 for Windows (Stata Corp., College Station, TX). All results are expressed as mean ± standard deviation. The statistical significance of intergroup differences, for non-normally distributed data, was evaluated by means of Kruskall-Wallis test. Spearman rank correlation coefficient was used when appropriate. The paired Student t test was applied for comparison of laboratory findings in the same subject. P values less than 0.05 were considered statistically significant.

Results

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. References

Characteristics of Patients.

The major clinical and biochemical parameters of the patients included in the study are listed in Table 1. Among the 18 enrolled patients, the cause of acute viral hepatitis was hepatitis A virus in 7, hepatitis B virus in 8, and hepatitis C virus in 3. No co-infection was demonstrated. At Doppler ultrasound examination, 10 patients (55.6%) had an increased spleen area (slight to moderate increase; 45 cm2 or greater and 65 cm2 or less in 9 patients, and major increase, 76.1 cm2, in 1 patient). An increase in spleen size is often observed during the acute onset of viral hepatitis.13 One patient showed a biphasic hepatic vein waveform, and 1 patient showed a moderately reduced mean portal vein velocity (19 cm/second). No patient showed a coarse echo pattern or irregularities of the liver surface. Finally, occurrence of a slightly bright liver was demonstrated in 1 patient. At the time of enrollment and during the follow-up, no patient showed clinical and biochemical features of fulminant hepatitis, and aminotransferases returned to normal values within 1 to 5 months in all subjects. Variation of biochemical parameters from the onset to the resolution of acute viral hepatitis are reported in Table 1. No patient underwent treatment with antiviral agents during the period of observation described in the current study. The mean success rate/mean interquartile range of LSM at the 3 time points were 97 ± 6.6% to 1.2 ± 0.8%, 96.2 ± 9% to 1.4 ± 1.2%, and 98.1 ± 4.9% to 1.3 ± 0.7%, respectively.

Table 1. Clinical and Laboratory Findings in the Study Population
Characteristic
  1. Results are expressed as mean ± SD.

  2. Abbreviations: BMI, body mass index; INR, international normalized ratio; GGT, gamma glutamyl-transpeptidase; ALP, alkaline phosphatase.

Age (yrs)40.9 ± 16.3
Male gender, n (%)10 (55.6%)
BMI (kg/m2)23.7 ± 3.6
Ex-drinker, n0
Signs or symptoms, n (%)—Anorexia12 (66.7%)
 —Nausea and vomiting5 (27.8%)
 —Abdominal pain4 (22.2%)
 —Malaise or flu-like syndrome15 (83.3%)
 —Jaundice13 (72.2%)
 —Others3 (16.7%)
 OnsetResolutionOnset vs. resolution
Total bilirubin (mg/dL)5.9 ± 5.60.7 ± 0.2P < 0.0001
Albumin (g/dL)3.8 ± 0.33.7 ± 0.2NS
INR1.2 ± 0.21.1 ± 0.1NS
γ-GT (U/L)274.3 ± 211.932 ± 6P < 0.0001
ALP (U/L)201.4 ± 102.292 ± 41P < 0.0001
Ammonia (μg/dL)51 ± 1947 ± 23NS
Glucose (mg/dL)80.2 ± 34.875 ± 40.2NS
Platelet count (109/L)240 ± 85.6256 ± 97NS
Creatinine (mg/dL)0.8 ± 1.20.7 ± 0.2NS

Variation of Aminotransferase Levels and LSM During the Course of Acute Hepatitis.

Table 2 shows aminotransferase levels and LSM for each patient at the 3 points considered in the study. In all patients, the degree of liver stiffness corresponding to the peak increase of aminotransferases exceed the cutoff values proposed for the prediction of significant fibrosis and cirrhosis (7 and 12 kPa, respectively).2 A progressive and significant reduction in LSM was observed (P < 0.0001) in the follow-up period in parallel with the reduction of aminotransferase levels (P < 0.0001) (Fig. 1). When aminotransferase levels were reduced to 2 ULN or less, a normalization of LSM values (<7 kPa) was observed in all patients except in patient 15, who showed a liver stiffness of 10 kPa at this time point (Table 2). A statistically significant, positive correlation was found between both aminotransferases and LSM at the onset of acute viral hepatitis (r = 0.53, P = 0.02 and r = 0.51, P = 0.03 for ALT and AST, respectively) (Fig. 2). This correlation remained statistically significant at all later observation points only for AST, whereas it was no longer present for ALT at the last time point. No significant difference was observed in the relationship between aminotransferase levels and LSM values in the different etiological groups of viral hepatitis.

Table 2. Sequential Determinations of Aminotransferase Levels (ALT, AST) and LSM During the Course of Acute Hepatitis
Patients (n, etiology)IIIIII
ALTASTLSMALTASTLSMALTASTLSM
  1. Aminotransferase levels and liver stiffness measurements at the 3 different time points: I. peak increase in aminotransferase; II. aminotransferase 50% or less of the peak; III. aminotransferase levels ≤ 2 ULN. Results are expressed in U/L for aminotransferase and in kPa for LSM. Mean values were reported ± SD. Abbreviations: LSM, liver stiffness measurement; ALT, aspartate aminotransferases; AST, alanine aminotransferases.

1, HBV2590147710.110006506.142284.8
2, HCV9178138.83671235.970324.9
3, HAV14379809.87134357.475795.4
4, HBV105791112.63173471280726.5
5, HAV11176168.8234418.845325.5
6, HAV12916327.25432764.878564.2
7, HCV117561810.41981118.848356.9
8, HAV3159177615.3114783212.162786.8
9, HAV215417858.8199976.442335.4
10, HBV14325888.5202657.465396.1
11, HAV2266162810.21104756845766.5
12, HBV11565211450023010.845606.4
13, HAV2594172015.3124384211.254656
14, HCV62845511.43011476.225266.1
15, HBV31912963311540102718.5607510
16, HBV5170252121.323578351660786.5
17, HBV2399273514.410248529.252736.5
18, HBV235612989.99875648.980526.2
Mean values2004.9 ± 1115.41335.4 ± 795.912.7 ± 5.7776.4 ± 580.6457.2 ± 337.19.4 ± 3.657.1 ± 15.654.9 ± 20.36.2 ± 1.2
thumbnail image

Figure 1. Sequential relationship between aminotransferase levels (ALT and AST) and LSM at different time points (I. peak increase in aminotransferase; II. aminotransferase 50% or less of the peak; III. aminotransferase levels ≤ 2 ULN). The mean aminotransferase concentrations are reported in the primary y-axis in shaded columns, and the mean liver stiffness values (dashed line) are shown in the secondary y-axis. ALT, aspartate aminotransferases; AST, alanine aminotransferases; LSM, liver stiffness measurement; kPa, kilopascal.

Download figure to PowerPoint

thumbnail image

Figure 2. Relationship between aminotransferase (ALT and AST) and LSM in whole patient population at the onset of acute viral hepatitis. ALT, aspartate aminotransferases; AST, alanine aminotransferases; LSM, liver stiffness measurement; kPa, kilopascal.

Download figure to PowerPoint

Discussion

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. References

Transient elastography is a novel and promising clinical methodology for the rapid and noninvasive assessment of disease progression in viral and nonviral CLD. This methodology is currently subjected to extensive validation in cross-sectional and longitudinal studies. A major endeavor in this process of validation concerns the identification of potential factors leading to an overestimation or underestimation of the fibrotic transformation of liver tissue assessed by this technique. In this context, extensive inflammatory infiltration, hepatocyte swelling, and tissue edema, which are relevant components of the chronic wound healing and fibrogenic process, could represent important confounding factors. This is suggested by recent reports highlighting a potential relationship between the degree of necroinflammatory activity or peak increases in aminotransferase levels and liver stiffness in patients with CLD.5, 6

To provide conclusive information on this hypothesis, the current study was conducted in patients with acute viral hepatitis without apparent history of liver disease. In acute viral hepatitis, liver tissue alterations are characterized by the presence of extensive inflammatory infiltration, hepatocyte swelling, and tissue edema, without fibrosis. In addition, these changes are in general self-limiting and characterized by resolution within a relatively short period. During the clinical course, monitoring of disease activity is ensured by assessing serum level of aminotransferases and other biochemical markers.

The results of the current study strongly indicate, for the first time, that liver tissue modifications associated with acute liver damage significantly influence LSM, providing values that have been associated with advanced fibrosis and cirrhosis, in patients with CLD. The contribution of nonfibrotic modifications to LSM is supported by a progressive normalization of stiffness values in parallel with the decrease of aminotransferase levels. Interestingly, LSM values were correlated with aminotransferase levels at the onset of acute viral hepatitis, when the presence of tissue inflammation and edema are likely to be maximal.

For common clinical practice and ethical considerations no patient was subjected to liver biopsy, and therefore acute liver damage could only be assessed by the peak increase and the subsequent modifications of serum biochemical markers. Although the preexisting presence of tissue fibrosis could not be ruled out histologically, the rapid and parallel decrease of LSM values below the proposed cutoff levels for significant fibrosis, the strict inclusion criteria, and the extensive clinical evaluation allowed us to bona fide rule out preexisting significant fibrosis in all patients but one.

A key consideration emerging from the results of the current study concerns the need of carefully considering the extent of necroinflammatory activity in future studies aimed at further validating transient elastography, particularly in patients with absent or low-stage liver fibrosis (that is, F0-F2 METAVIR). In addition, it is advisable to critically consider LSM values obtained in the concomitance of aminotransferase flares, especially in patients with viral hepatitis. Finally, it appears clear that LSM does not represent a reliable instrument to detect the presence of advanced fibrosis and cirrhosis in patients presenting with a clinical picture of acute hepatitis.

References

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. References