Figure 1.
Quantification of HBsAg, anti-HBs, and HBV DNA, including characterization of HBV genotype on DBS using commercial kits. This study used DBS paired with plasma as a reference method.
Figure 2.
Evaluation of DBS storage relative to titer in HBsAg and anti-HBs tested by immunoassay.
DBS samples were tested after storage at room temperature during 1, 3, 7, and 14 days. Each line represents 5 positive samples (black symbols) and 3 negative samples (white symbols). The dotted line represents the positive cutoff value for each parameter. (A) Evaluation of DBS storage relative to titer in HBsAg (IU/mL). (B) Evaluation of DBS storage relative to titer in anti-HBs (IU/mL).
Table 1.
Limit of detection in plasma and DBS.
Figure 3.
Regression analysis and Bland-Altman representation of titer differences in DBS and plasma of HBsAg levels and HBV DNA levels.
(A) Linear regression analysis of HBsAg levels for the 100 matched DBS-plasma pairs analyzed by immunoassay. (B) Bland-Altman analysis was used to determine the agreement between the HBsAg titer by plotting the differences between the two samples against the averages of the two techniques. (C) Linear regression analysis of HBV DNA levels for the 50 matched DBS-plasma pairs analyzed by real-time PCR quantitative assay. (D) Bland-Altman analysis of HBV DNA.
Figure 4.
Evaluation of DBS storage relative to HBV DNA titer.
DBS samples were tested after storage at room temperature during 1, 3, 7, and 14 days. Each line represents 5 positive samples (black symbols) and 3 negative samples (white symbols). The dotted line represents the positive cut-off value (20 IU/mL).
Table 2.
HBV Genotype characterization in DBS and plasma samples.