A non-invasive algorithm accurately predicts advanced fibrosis in hepatitis C : a comparison using histology with internal-external validation

Background/Aims: Biochemical tests and ultrasonography (US) are useful in the non-invasive assessment of liver fibrosis in patients with chronic hepatitis C (CH-C); however histology remains the reference standard. This multicenter, cross-sectional cohort study evaluated the accuracy of APRI (AST-to-platelet-ratio-index) and liver surface ultrasound nodularity (LSN), singularly and sequentially combined in an algorithm, in diagnosing advanced fibrosis (i.e. METAVIR F3, F4), to derive a prediction rule to confirm or exclude F3, F4. Methods: Four hundred and thirty consecutive CH-C patients with elevated ALT, grouped into a first cohort (training set), and an internal and an external validation cohort, were studied. APRI and LSN were compared to liver biopsy and sequentially combined in order to obtain a predictive rule for advanced fibrosis METAVIR F3, F4. Results: LSN was negative and APRI ≤ 1 in 185/430 patients, whereas LSN was positive and APRI > 2 in 46/430 cases, with a 94% diagnostic accuracy for presence/absence of F3, F4, respectively. In a further 60/430 patients, F3, F4 was detected with an accuracy of 83%. In the remaining cases no classification was possible. Conclusions: An algorithm based on APRI and LSN confirms or excludes F3, F4 in 54% of CH-C patients with elevated ALT and suggests a highly probable diagnosis in a further one-sixth of patients, thus rendering liver biopsy unnecessary in these patients.