Diagnostic value of HBsAg in HBV Infection among patients referred to Pathologist Lancet Laboratory in Nairobi, Kenya

Abstract

Quantification of Hepatitis B virus (HBV) Deoxyribonucleic acid (DNA) levels has been used to manage chronic hepatitis B (CHB) patients on treatment. However, HBV DNA quantification techniques are costly and rarely done. Measuring of hepatitis B surface antigen (HBsAg) levels by chemiluminescent micro-particle immunoassay has been suggested as an alternate marker. This study sought to determine the sero-prevalence of HBV, the chronicity of HBV and correlated the HBsAg with HBV DNA serum levels among patients attending Pathologist Lancet Laboratory in Nairobi, Kenya. Of all the patients routinely tested for HBsAg, those meeting the recruitment criteria were consented and recruited in this study. Blood samples were obtained from 2246 patients attending Pathologist Lancet Laboratory for HBV testing. A sociodemographic questionnaire was administered. The HBsAg levels were measured by Roche Cobas e 411 analyzer with Elecsys HBsAg II Quant reagent kits (Roche Diagnostics, South Africa, SA) while the HBV DNA viral load (IU/mL) was measured using Cobas AmpliPrep/CobasTaqMan HBV Test, version 2.0(Roche Molecular Systems, South Africa, SA). Overall, 346/2246 (15.4%) were HBsAg positive. The mean age (Standard deviation) was 37.5(10.8) years. The majority 129(37.3%) aged between 31 and 40 years, 221 (63.9%) were male, 111(32.1%) consumed alcohol for two or more years,297(85.8%) did not use condom in their last two sexual encounters, 62(17.9%) shared personal effects with other family members, 78(22.5%) had received blood transfusion, 144(41.6%) had undergone invasive procedures before, 122(35.3%) had received HBV vaccination while 144(41.6%) had HBV related symptoms. Out of the 346 HBsAg positive 173 (50%) were also positive for either HCV or HDV and were excluded for further correlation analysis. For the 173 patients that were included for correlation analysis, the majority, 142 (82.1%) were hepatitis B e antigen (HBeAg) negative and were considered chronically infected. The overall mean (Log10) of HBsAg (SD) titter was 3.58 (0.39) IU/mL and an overall mean (Log10) of HBV-DNA (SD) of 2.89 (1.62) IU/mL. The HBV DNA levels was significantly different between HBeAg positive and negative patients (P = 0.001) similar to the HBsAg levels (P = 0.032). There were22/31 (70.9%)HBeAg positive participants with HBV DNA ≥ 20,000 IU/ML and 14/142 (9.9%) HBeAg negative with HBV DNA ≥ 2000 IU/ML. There was a significant but weak correlation between HBV DNA and HBsAg (r = 0.171; P= 0.024).The prevalence of HBV was 15.4% and a significant proportion, 82.1% were chronically infected with HBV.Serum quantitation of HBsAg may not replace HBV DNA level estimation among patients with CHB in Nairobi Kenya. It is an estimate and not a gold standard, but it can definitely have a role in correlating disease especially in stable patients after an initial HBV DNA is performed to save expenses and minimize the cumbersome nature of HBV DNA testing. In additional larger prospective study, be conducted to re-evalute the correlation if any between HBV DNA and HBsAg levels in Kenya.