Clinical Implications of Quantitative Hepatitis B Virus DNA Measurements

The development of amplification techniques, home-made and commercial has revolutionised the ability to detect the hepatitis B virus both qualitatively and quantitatively. The objectives of this thesis were to describe the clinical implications of quantitative HBV DNA measurements. In chapter 2 we describe the predictive value of quantitative HBV DNA measurements in identifying non-responders to Interferon-alpha therapy. To reduce unnecessary exposure to treatment physicians must decide at an early stage whether continuation of treatment has a reasonable chance of success for the individual patient. The clinical value of surrogate tests proposed for the assessment of disease activity or viral replication such as HBeAg must be assessed. The objectives of our study were first to evaluate quantitative HBeAg measurements versus quantitative HBV DNA measurements for prediction of non-response and response for IFN-α treated patients. Secondly, we evaluated the value of precise quantitative HBV DNA measurements for predicting non-response and response of IFN-α treated patients. Monitoring with quantitative HBV DNA levels was superior to monitoring with quantitative HBeAg levels. This study also showed that quantitative HBV DNA testing at baseline in combination with a decrease between baseline and week 12 has a high predictive value for identifying patients who have virtually no chance of reaching a sustained response with IFN therapy. Quantification of HBV DNA enabled clinicians to monitor clinical situations such as the effect of therapy and the emergence of drug-resistant variants. These mutations are mainly identified after an increase in the HBV DNA load in serum is observed.