Quantification of HBsAg: Basic virology for clinical practice

Table 1 Recent clinical studies with quantification of hepatitis B surface antigen titers in hepatitis B virus infection

Author	Antiviral therapy	Correlation	Prediction	Clinical results
Deguchi et al[23]	-	HBV DNA	-	qHBsAg is higher in HBeAg(+)
Chen et al[28]	-	HBV DNA	-	qHBsAg is higher in HBeAg(+) and high HBV DNA levels, whereas qHBsAg is low in low HBV DNA level CHB
Werle-Lapostolle et al[29]	ADV	cccDNA, HBV DNA	-	HBsAg and cccDNA decrease with ADV
Kohmoto et al[30]	LAM	HBV DNA	-	qHBsAg is helpful for early detection of drug resistant strains
Wursthorn et al[35]	Peg-IFN + ADV	cccDNA	-	Peg-IFN + ADV decreases cccDNA and HBsAg, which are well correlated
Chan et al[36]	Peg-IFN + LAM	cccDNA	Low baseline qHBsAg can predict SVR	Peg-IFN + LAM decreases cccDNA and HBsAg, which are well correlated
Manesis et al[31]	IFN vs LAM	HBV DNA	Low baseline qHBsAg can predict SVR	IFN induces sharper decrease in qHBsAg than LAM
Wiegand et al[27]	FAM ± LAM	HBV DNA (not correlated)	Decline of qHBsAg can predict HBsAg loss	2 log drop to below 100 IU/mL is associated with HBsAg clearance
Moucari et al[32]	Peg-IFN	HBV DNA	Early qHBsAg drop can predict SVR	qHBsAg may be useful to optimize Peg-IFN therapy
Brunetto et al[33]	Peg-IFN ± LAM vs LAM	HBV DNA	On-treatment qHBsAg decline can predict sustained HBsAg loss	qHBsAg < 10 IU/mL at week 48 and 1 log decline predict sustained HBsAg clearance to optimize treatment strategy
Lau et al[37]	Peg-IFN ± LAM	-	On-treatment qHBsAg can be used as an early predictor of SVR	In HBeAg(+) patients, qHBsAg reduction through weeks 12, 24 and 48 were higher in patients with HBeAg seroconversion
Marcellin et al[38]	Peg-IFN ± LAM	-	qHBsAg at week 12 can predict long-term HBsAg clearance	35% of patients who had qHBsAg < 1500 IU/mL at week 12 cleared up HBsAg by 4 yr post-treatment
Lu et al[39]	Peg-IFN ± LAM	cccDNA	qHBsAg was superior to cccDNA and serum HBV DNA in predicting SVR	Area under ROC curve with qHBsAg, cccDNA and HBV DNA was 0.769, 0.734, and 0.714, respectively, for predicting SVR
Brunetto et al[65]	Peg-IFN ± LAM	-	On-treatment qHBsAg can be used as an early predictor of SVR	On-treatment decline in HBsAg appears to be genotype dependent. Genotype B patients showed the most rapid and pronounced decline
Hou et al[66]	Peg-IFN vs LAM	-	-	Peg-IFN was superior to ADV in HBeAg seroconversion and qHBsAg decline in LAM-resistant patients

HBV: Hepatitis B virus; HBsAg: Hepatitis B surface antigen; qHBsAg: Quantification of HBsAg titers; HBeAg: Hepatitis B e antigen; CHB: chronic hepatitis B; ADV: Adefovir; LAM: Lamivudine; Peg-IFN: Pegylated interferon; cccDNA: Covalently closed circular DNA; FAM: Famciclovir; SVR: Sustained virologic response; ROC: Receiver operating characteristic.