quality control planning of a hepatitis b viral load laboratory-developed assay

background and objectives: hbv dna monitoring is important in management of chronic viral hepatitis b infection. hbv dna measurements are carried out over period of months to years. so the analytical system must be stable and reproducible. the aim of this study was to determine the performance characteristics and to plan a statistical quality control system of a laboratory-developed real-time quantitative pcr assay for hbv dna quantification.methods: values of systematic and random error at two clinical decision points;4.2 log iu/ml (20000 iu/ml) and 3.2 log iu/ml (2000 iu/ml) were determined. candidate quality control procedures were selected and performance of the method by application of normalized operational process specification (opspecs) charts was determined.results: the performance of the assay at level of 4.2 log iu/ml and 3.2 log iu/ml were excellent and good respectively. moreover, a13.5s rule with two measurements offered 90% probability of error detection at level of 4.2 log iu/ml, while no rule offered 90% probability of error detection at level of 3.2 log iu/ml.conclusion: minimizing the formation of primer-dimer and nonspecific products and concentrating the target dna during the purification process are proposed for accurate quantitative pcr particularly when ct values are high.