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Paper text:
the level of serum hbv dna predicts the natural history of chb in individual patients . sustained reduction in hbv dna levels during long - term nucleos(t)ide analogue therapy
clinical studies have shown that early and profound suppression of viral levels lead to improved outcomes and less antiviral resistance .
profound and sustained inhibition of viral replication is therefore the most important goal of antiviral therapy in chronic hepatitis b. the roadmap provides physicians with the ability to achieve this goal by measuring viral levels during treatment to assess response to oral therapy .
early monitoring of the virologic response to oral nucleos(t)ide therapy is essential in order to identify patients with suboptimal responses so that an appropriate change in therapy can be initiated .
use of the strategies outlined in the roadmap concept should permit clinicians to provide individualized treatment throughout the course of therapy and thus enhance long - term patient outcomes .
several large observational , longitudinal studies of the natural history of chronic hepatitis b ( chb ) have demonstrated that high levels of hepatitis b virus ( hbv ) replication are associated with long - term risk of cirrhosis , decompensation , hepatocellular carcinoma , and liver - related mortality . 
 the corollary is also true  profound and sustained suppression either spontaneously or during antiviral therapy will prevent disease progression and complications . 
 multiple analyses of various baseline factors and on - treatment responses have identified the absolute hbv dna level after 24  weeks of therapy as the best predictor of long - term efficacy . 
 lower 24-week serum hbv dna levels after lamivudine , telbivudine , or entecavir are associated with higher rates of maintained hbv dna nondetectability , alt normalization , hbeag seroconversion , and lack of resistance . 
 patients with undetectable serum hbv dna levels after 24  weeks have the best long - term outcomes while those with levels remaining above 10,000 copies per ml are unlikely to benefit from long - term therapy with that particular agent and either the addition or switch to another antiviral agent with increased potency but without cross resistance could be considered at this time point . in the future , 
 improved on - treatment monitoring should facilitate treatment strategies to optimize long - term outcomes among patients receiving oral antiviral therapy for chb .