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To the Editor:

We read with great interest the article titled “Diagnosis of fibrosis and cirrhosis using liver stiffness measurement in nonalcoholic fatty liver disease”, published in HEPATOLOGY.1 In this work, Wong et al. evaluated the diagnostic accuracy of transient elastography by Fibroscan in the measurement of liver fibrosis and cirrhosis in patients with nonalcoholic fatty liver disease (NAFLD). In this study, 309 consecutive adult patients with NAFLD, mean age 51 ± 11 years, underwent transient elastography and liver biopsies, but only 246 were included in the analysis. Interestingly, the authors found that at cutoff value of 7.9 kPa, the negative predictive values to exclude fibrosis stage ≥F3 disease were 52% and 97%, respectively. These results are very similar to those reported by Nobili et al.2 in pediatric patients. In fact, transient elastography performed on 52 consecutive children with biopsy-proven nonalcoholic steatohepatitis (mean age 13.6 ± 2.44 years), showed that cutoff values between 7 and 9 kPa predict fibrosis stages 1 or 2, and a value ≥9 kPa are associated with the presence of advanced fibrosis. Similarities in the cutoff values found in these two articles show that the patient's age, as well as body mass index, are irrelevant factors to establish the diagnostic accuracy of Fibroscan. However, the question remains whether assessment of fibrosis by transient elastography is a noninvasive technique able to completely replace biopsy or if its power to diagnose advanced fibrosis in patients with NAFLD remains modest.

Our experience with children with NASH suggests that transient elastography by Fibroscan is an accurate and reproducible methodology to discriminate patients without any degree of fibrosis from those with advanced fibrosis; Wong et al. indicate that this consideration is equally applicable in adults.

Although all these findings reinforce the idea that the measurement of liver stiffness by transient elastography may be considered a screening test, there is ample evidence3, 4 that its combination with blood markers may significantly improve the accuracy of the noninvasive diagnosis of liver fibrosis and, consequently, decrease the necessity of liver biopsy, both in adults and children.

References

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  • 1
    Wong VW, Vergniol J, Wong GL, Foucher J, Chan HL, Le Bail B, et al. Diagnosis of fibrosis and cirrhosis using liver stiffness measurement in nonalcoholic fatty liver disease. HEPATOLOGY 2009; doi:10.1002/hep.23312.
  • 2
    Nobili V, Vizzutti F, Arena U, Abraldes JG, Marra F, Pietrobattista A, et al. Accuracy and reproducibility of transient elastography for the diagnosis of fibrosis in pediatric nonalcoholic steatohepatitis. HEPATOLOGY 2008; 48: 442448.
  • 3
    Boursier J, Vergniol J, Sawadogo A, Dakka T, Michalak S, Gallois Y, et al. The combination of a blood test and Fibroscan improves the non-invasive diagnosis of liver fibrosis. Liver Int 2009; 29: 15071515.
  • 4
    Nobili V, Parkes J, Bottazzo G, Marcellini M, Cross R, Newman D, et al. Performance of ELF serum markers in predicting fibrosis stage in pediatric non-alcoholic fatty liver disease. Gastroenterology 2009; 136: 160167.

Anna Alisi Ph.D.*, Massimo Pinzani M.D.†, Valerio Nobili M.D.*, * Liver Unit, Bambino Gesù Children's Hospital, and Research Institute, Rome, Italy, † Department of Internal Medicine, University of Florence, Firenze, Italy.