Australian liver association (ALA) expert consensus recommendations for the use of transient elastography in chronic viral hepatitis

2014 Journal of Gastroenterology & Hepatology

The technique of Transient Elastography (TE) using FibroScan (Echosens, Paris) represents one of a range of non-invasive tools specifically developed for the estimation of the degree of hepatic fibrosis. However, several unique features of this device have resulted in a rapid uptake of this technology since its introduction into Australia in 2008. These features include; simplicity of operation, speed of assessment and a high degree of safety and tolerability. The result is a test with attributes suitable for use in clinical practice. [...]
Practicalities of TE
Consensus Recommendations
- TE should be performed according to a standardized protocol consistent with existing guidelines with the patient in the supine position, right arm in full abduction.
- The reference site of LSM is the midaxillary line in the first intercostal space below the liver dullness upper limit. The phase of respiration may be relevant and should be taken into account.
- The patient should fast for at least 2 hours prior to the procedure
- The M probe is suitable for most patients but ideally the XL probe should be used for patients with a skin-to-capsule distance of > 25mm.
- A reliable assessment must include an IQR/M of ? 0.30. We also strongly recommend a minimum of 10 valid shots. The evidence supporting a 60% success rate is weak however, for consistency with international standards and for research purposes, this is desirable.
- There is reasonable evidence indicating TE can be performed in a reliable way by both physicians and technicians, however a learning curve is apparent. At this stage no specific recommendations can be made regarding the number of training examinations that should be performed before independent practice. Operator experience is however a factor determining TE accuracy and expert proficiency may require > 500 examinations.
- Result interpretation should be mindful of the error inherent to both liver biopsy and non-invasive technologies such as TE. It should be appreciated that LSM is a guide to severity of fibrosis and ideally results should be expressed in terms of probability rather than certainty. We recommended against using terms such as normal or no-fibrosis due to the overlap between early fibrosis stages, no or minimal fibrosis would be more accurate. Consistent with most investigations and diagnostic tests, LSMs need to be considered in light of the clinical context and interpreted accordingly.
- TE / other non-invasive tools and liver biopsy should be used in an integrated way to allow safe, accurate and timely evaluation of patients with chronic liver diseases.
- Reporting should include detail required for independent analysis of the quality of the test and ideally include; anatomical site of assessment, probe type, number of valid shots, median LSM, IQR and IQR/M, fasting status and ALT.

TE in Chronic Hepatitis C (CHC)
Consensus Recommendations
- There is substantial data indicating TE provides additional information to the clinician that may assist in establishing treatment priorities and clinical decision making for the management of CHC provided that consideration is given to factors that may adversely affect its performance.
- For patients not undergoing a liver biopsy, TE or another validated noninvasive technique should be performed in all patients with HCV infection.
- There is no data regarding the timing of repeat LSM assessments in individual patients although many groups currently perform TE every 1-2 years for patients undergoing surveillance while awaiting CHC therapy. Data supporting ability of TE to reliably detect progression is limited to small studies.
- For significant fibrosis (?F2) the proposed existing cutoffs (6.8kPa-8.8kPa) have a high positive predictive value (83-97%) but variable negative predictive value (23-85%) and therefore a higher LSM is better at confirming the presence of ?F2 rather than excluding it. There are many factors that limit TE ability to distinguish F1 from F2. These include limitations of liver biopsy itself particularly for this early stage of liver fibrosis.
- For advanced fibrosis (? F3), a cutoff ranging from 8.9-10.8 kPa has a PPV and NPV of 71%-89% and 78%-95% respectively.
- For cirrhosis the proposed existing cutoffs (11.9kPa-14.8kPa) offer a positive predictive value ranging from 52%-85%. Therefore an LSM above these cut offs may not, on its own be enough to confirm the presence of cirrhosis. These cutoffs are however associated with a high negative predictive value (?95%) and therefore function well for the exclusion of cirrhosis.
- Treatment decisions should not be solely based on LSM.
- Current guidelines recommend avoiding response-guided therapy in genotype 1 patients with cirrhosis although there is no data regarding the use of TE assessment in the determination of CHC treatment duration. Therefore this decision needs to be individualized.
- TE may overestimate the degree of hepatic fibrosis in patients with early stage disease and ALT elevation. The interpretation of TE should be made in conjunction with knowledge of the ALT and TE should be interpreted with caution in patients with a markedly elevated ALT.
- There is evidence suggesting that TE may improve the prognostic stratification of patients with cirrhosis beyond that offered by biopsy or Childs-Pugh /MELD score. Further longitudinal studies are required.

TE in Chronic Hepatitis B (CHB)
Consensus Recommendations
- We recommend TE (or alternative non-invasive tests) as the initial investigation for determination of hepatic fibrosis in individuals with chronic hepatitis B not undergoing liver biopsy.
- We recommend TE (or alternative non-invasive tests) for patients who start treatment without liver biopsy in order to establish a baseline LSM. As in HCV, TE has a higher NPV than PPV and is therefore better at excluding cirrhosis than confirming it.
- Because an assessment of fibrosis is only one of several factors determining management decisions, treatment recommendations and follow-up, TE should be interpreted as part of specialist care and is not recommended for isolated use in primary health care to determine suitability for treatment or specialist referral.
- In view of the relationship between elevated ALT associated with viral flares it would seem sensible to measure liver stiffness where practical, once the elevation of ALT has subsided. Testing of ALT around the time of LSM is therefore recommended.
- Interpretation of Liver stiffness measurement in patients with elevated ALT should take into account that necroinflammation can contribute to stiffness and therefore result in an overestimation of fibrosis stage. The use of algorithms that incorporate ALT may mitigate against this.

Pubmed : 25532416