A novel non-invasive index using AFP and APTT is associated with liver fibrosis in patients with chronic hepatitis B infection: a retrospective cohort study

OBJECTIVE A liver biopsy is the 'reference standard' for diagnosing and staging liver fibrosis but with many disadvantages. Therefore, developing a non-invasive index for predicting fibrosis is very valuable. We developed and validated a novel non-invasive index for predicting significant fibrosis in patients with chronic hepatitis B infection. DESIGN A retrospective cohort study. SETTING Chronic hepatitis B virus-infected patients were recruited in the Department of Infectious Disease in the First Affiliated Hospital of Zhejiang University. PARTICIPANTS A total of 506 patients were enrolled, and patients were randomly divided into estimation (n=253) and validation (n=253) cohorts. PRIMARY AND SECONDARY OUTCOME MEASURES Chronic hepatitis B virus-infected patients were studied retrospectively using routine parameters. A novel index was developed from an estimation cohort and validated in another cohort. Liver histology was assessed for fibrosis according to the Xi'an Meeting Scoring System. The novel index using α-fetal protein (AFP) and activated partial thromboplastin time (APTT; denoted AA index) was compared with 10 other indices using receiving operating characteristics curves. Multivariate forward stepwise regression analysis revealed that AFP and APTT were significantly associated with the Xi'an Meeting Scoring System, and were used to calculate the AA index (log index=-9.164+0.114×AFP+0.236×APTT). RESULTS The AA index predicted significant fibrosis with an area under the curve of 0.822, exhibited a significantly higher area compared with the other 10 indices in the estimation cohort, and was validated in the validation cohort. CONCLUSIONS The AA index can be used to predict significant fibrosis, and may decrease the need for liver biopsy in patients with chronic hepatitis B infection.