Background: Transient elastography may help identify patients at greater risk for advanced fibrosis but there is a significant overlap between fibrosis stages and values with transient elastography. In some conditions, like fatty liver, elastography may be less helpful than in others (eg. chronic viral hepatitis).
A recent study (J Pediatr 2018; 198: 84-9) examined the results of transient elastography in 267 children (97 for calibration, 170 for validation) between 2006-2016. The median age was 13 years. Liver diseases included autoimmune (21%), viral (19%), fatty liver (11%), cholestatic (9%), primary sclerosing cholangitis (9%) and post-transplantation (12%).
- Cut points to discriminate F3-F4 and F4 were >8.6 kPa and >11.5 with 81% and 84% accuracy, respectively in calibration cohort
- To discriminate F3-F4 and F4 in validation cohort, these cut points, >8.6 kPa and >11.5, had accuracy of 67% and 75% respectively
Figure 2 provides much greater detail in the typical values for each Metavir stage. For example, in the calibration cohort, the median values and range were the following:
- F0 6.0 (3.2-12.4)
- F1 6.2 (3.2-75)
- F2 5.8 (2.5-52.7)
- F3 10.3 (4.9-32.6)
- F4 20.5 (5.9-68.1)
In the validation cohort, values were similar:
- F0 6.2 (3.0-75.0)
- F1 7.1 (3.3-31.6)
- F2 7.1 (2.5-52.7)
- F3 9.6 (4.4-75.0)
- F4 20.8 (6.8-75.0)
My take: Elastography in measuring liver stiffness is a lot like checking a CRP for inflammatory bowel disease. That is, it can be helpful but cannot be relied on the same way as many radiographic tests (eg. CT scans for appendicitis).
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