Haematological alterations and diagnostic performance of blood cell indices in hepatitis B virus infection in Edo-North, Nigeria: a comparative cross-sectional study

Hepatitis B virus (HBV) causes systemic haematological changes, yet the clinical significance of routine blood cell indices in characterizing these alterations in Edo-North, Nigeria, remains under-investigated. This study evaluated haematological abnormalities in HBV infection and assessed the utility of blood cell indices in reflecting disease severity.

A quantitative comparative cross-sectional study was conducted among 400 participants (200 HBV-infected, 200 healthy controls) in Etsako West Local Government Area, Edo North Senatorial District, Nigeria. Venous blood samples were collected into ethylenediaminetetraacetic acid (EDTA) tubes and haematological parameters were measured using an automated analyser. HBV infection was confirmed by HBsAg rapid immunochromatographic testing with ELISA confirmation. Data were analysed using Python 3.11.13. Normality was assessed with the Shapiro–Wilk test; continuous variables were compared using t-tests or Mann–Whitney U tests, categorical variables with χ² tests, and group differences across HBV severity were evaluated with one-way ANOVA or Mann–Whitney U tests. Receiver operating characteristic (ROC) curve analysis determined the diagnostic utility of selected indices. Statistical significance was set at p < 0.05.

HBV-infected participants had significantly lower HCT, HGB, PLT, RBC, LYM, MCV, MCH, and MCHC, and higher WBC, MONO, and GRAN counts (all p < 0.001). Anaemia occurred in 23.0% (predominantly mild), thrombocytopenia in 18.5%, and leucopenia in 16.5%. Haemoglobin (HGB) demonstrated moderate-to-good discriminative ability across severity groups (AUC = 0.72–0.77). RBC achieved high sensitivity (82.5%) and specificity (91.2%) at a single optimal cut-off but an AUC of 0.47, indicating that discriminatory ability was not sustained across the full range of thresholds. WBC and GRAN showed limited diagnostic value.

Haematological profiles, particularly HGB and RBC, are significantly altered in HBV infection and correlate with disease severity, supporting their utility as adjunct clinical indicators of systemic disease burden and severity stratification in confirmed HBV-infected individuals in resource-limited settings. These findings do not propose haematological indices as alternatives to HBsAg-based serological diagnosis, which remains the appropriate and recommended primary diagnostic approach.