Assessment of fibrosis in chronic hepatitis B using APRI, FIB-4, FIB-5, FIB-6, and S-Index: Comparison with histology

Chronic hepatitis B (CHB) remains a major cause of cirrhosis and hepatocellular carcinoma worldwide. Although liver biopsy is the reference standard for fibrosis staging, its limitations have prompted the development of noninvasive serum-based indices. This study aimed to compare aminotransferase-to-platelet ratio index (APRI), Fibrosis-4 index (FIB-4), Fibrosis-5 index (FIB-5), Fibrosis-6 index (FIB-6), and serum fibrozis indeksi (S-Index) with histology in patients with CHB. A total of 191 CHB patients who underwent liver biopsy between 2012 and 2024 were retrospectively analyzed. Fibrosis was staged using the METAVIR system and classified as non-significant (F0-F2) or significant (F3-F4). Serum-based fibrosis indices were calculated, and their diagnostic performance was assessed using receiver operating characteristic (ROC) analysis. Of the 191 patients, 75 (39.3%) had significant fibrosis (SF). APRI, FIB-4, FIB-6, and S-Index were significantly higher in patients with SF, whereas FIB-5 showed no discriminatory value. ROC analysis demonstrated modest accuracy overall: APRI (area under the curve [AUC] 0.661) provided the highest sensitivity but low specificity (88.0% and 38.8% respectively, P < .001), while FIB-4 (AUC 0.601, specificity 86.2% sensitivity 37.3%, P = .019) and FIB-6 (AUC 0.608, specificity 87.1%, sensitivity 44%, P = .014) were more specific but less sensitive. S-Index showed intermediate performance (AUC 0.601, specificity 62.07% sensitivity 58.67%, P = .021). Serum-based indices demonstrated limited but clinically relevant ability to discriminate SF in CHB, with modest AUC values. Despite their suboptimal diagnostic accuracy, their noninvasive, low-cost, and accessible nature supports their potential role in clinical practice. APRI showed high sensitivity but low specificity, limiting its standalone screening utility. FIB-4 and FIB-6 displayed relatively balanced performance, while S-Index showed modest but consistent accuracy. Overall, these scores may serve as adjunctive tools rather than definitive diagnostic methods and could have a role in longitudinal monitoring. Further validation in larger, multicenter prospective studies is warranted.