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In our cohort, age and gender were also found to be associated with a discordance between
FS and FT and between FT and APRI. Similar results were found in a previous study
evaluating the factors associated with a discordance between FT and liver biopsy in HCV
monoinfected patients, and this result was interpreted as a ‘technical artifact,’ since age and
gender are also included in the calculation of the FT score (28).
Factors independently associated with a discordance between FS and APRI were: age>45
years, BMI, GGT and ALT. Various confounding factors have been shown to influence and
limit the interpretation of FS values including fat and age (34-36). High BMI and older age
have been reported to be associated with a decreased success rate of Fibroscan (35). Also,
a positive relationship between ALT levels and liver stiffness measurements has already
been reported in acute hepatitis (37-39). Indeed, falsely elevated FS measures consistent
with cirrhosis have been reported when ALT levels are very high, probably because acute
hepatitis is associated with an inflammatory infiltrate and tissue edema, which are likely to
affect liver stiffness measurements. Thus, an increase of BMI, ALT or age could lead to a
failure of FS and could explain the discordance. However, in a recent study, which evaluated
factors that affected accuracy of FS, neither BMI, ALT and GGT, nor age, were found to be
associated with accuracy of FS (36).
In the sensitivity analysis, after exclusion of patients under atazanavir, with unreliable results
of FS or with ALT >5 fold the normal, the discordance rate between the tests was not
significantly improved. However, the effect of bilirubin and GGT on discordance between FT
and FS and between FT and APRI disappeared, but BMI and ALT still remained associated
with discordance between FS and APRI.
The main factors associated to a discordance between these non-invasive tests were the
biological parameters used for the calculation of FT. This suggested that FT could be
avoided in patients presenting some of the risk factor for discordance namely, elevated GGT
(>1.5N), total bilirubin >17µmol/L, α2-macroglobulin>3g/L, low apolipoprotein A1 or
lipodystrophy.
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