Novel indices to diagnose fibrosis in chronic HBV patients developed
medwireNews: Two research groups have developed noninvasive indices to detect significant fibrosis in treatment-naïve patients with chronic hepatitis B virus (HBV) infection, one using serum levels of Golgi protein 73 (GP73) and liver stiffness, and the other based on the ratio of gamma-glutamyl transpeptidase (GGT) to albumin.
The authors of both studies highlight the importance of accurately diagnosing fibrosis, as the presence of significant fibrosis (stage ≥2) is a major indication for initiating antiviral treatment.
In the first study, published in Liver International, the investigators found that serum GP73 levels were a significant and independent predictor of significant fibrosis among patients with chronic HBV (odds ratio [OR]=1.02 per 1 ng/mL increase, p<0.001).
And in a training cohort comprising 267 patients, serum GP73 levels identified individuals with significant fibrosis with an area under the receiver operating characteristic curve (ROC) value of 0.76, which was higher than that for the currently used indices, namely the aspartate transaminase-to-platelet ratio index (APRI) and fibrosis index based on four factors (FIB-4), at 0.69 and 0.66, respectively. But the highest area under the ROC value was achieved when GP73 levels were combined with liver stiffness as evaluated using transient elastography, at 0.85. The findings were similar in an independent validation cohort, which included 133 participants.
Therefore, Qing Xie, from Shanghai Jiao Tong University School of Medicine in China, and co-authors propose an algorithm based on these two parameters, such that a liver biopsy can be avoided when the GP73 and liver stiffness results are in agreement, but not if they are discordant.
Specifically, when GP73 and liver stiffness values were less than 63 ng/mL and 8.5 kpa, respectively, significant fibrosis could be excluded with an accuracy of 81.7%, whereas when values were equal to or above the cutoff, significant fibrosis was confirmed in 93.3% of cases.
The team points out that the algorithm could correctly classify around two-thirds of patients in the training and validation cohorts without the need for a liver biopsy.
The second study used data from 822 treatment-naïve patients to show that GGT and albumin values were significantly and independently associated with significant fibrosis, with respective ORs of 1.03 and 0.95 (p<0.001 and p=0.048).
And the GGT-to-albumin ratio (GAR) could detect the presence of significant fibrosis, severe fibrosis (stage ≥3), and cirrhosis (stage 4) with higher area under the ROC values than those for the APRI and FIB-4 indices in training (n=606) and validation (n=216) sets. For instance, the GAR index could distinguish individuals with significant fibrosis from those with no or minor fibrosis (stage≤2) with an area under the ROC value of 0.82 versus 0.70 and 0.68 for the APRI and FIB-4 indices, respectively (p<0.001 for both comparisons).
Writing in the Journal of Viral Hepatitis, the researchers note that “[t]he GAR has several attractive features, including parameters that are easy to quantify, a straightforward calculation, much lower cost than other noninvasive methods, and more importantly, it shows higher performance than FIB-4 and APRI.”
“Although GAR cannot replace liver biopsy, it can select the candidates for liver biopsy, avoid excessive liver biopsy and narrow down the group which really needs liver biopsy,” they write.
Qiang Li (Fudan University, Shanghai) and team also caution that in light of the low positive predictive values of the GAR index (34–61% for the different fibrosis stages), it is important that the index be used alongside other clinical and laboratory criteria.
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