What are the conditions that require an extended course of pegylated interferon? The fundamental treatment for chronic hepatitis B is antiviral, and pegylated interferon is a potent anti-hepatitis B virus drug with dual functions of antiviral and immunomodulation, high e antigen conversion rate and long-lasting immune response, which cannot be achieved by various nucleoside analogues. The efficacy of pegylated interferon is directly proportional to the dose and duration of treatment. The standard course of treatment for most adult patients is one year. However, in some special cases, it may be necessary to extend the course of treatment in order to achieve a more satisfactory outcome. So, which patients need a longer course of treatment? What is the duration of pegylated interferon treatment? The approved course of pegylated interferon is 12 months. There is no conclusive data on whether extending the course of treatment improves efficacy and whether extending the course of treatment results in a corresponding increase in adverse effects. The course of treatment can be extended for patients with a chance of surface antigen seroconversion based on multiple monitoring (e.g., E antigen/antibody or S antigen/antibody quantification), or can be discontinued or changed for those with very poor outcomes. Clinical practice has demonstrated that prolonging the course of therapy can improve outcomes. Patients with sustained immune control (HBeAg seroconversion and disappearance of HBsAg based on sustained suppression of viral replication) can significantly reduce the incidence of cirrhosis and hepatocellular carcinoma, improve quality of life and prolong survival. The disappearance of HBsAg is considered a “clinical cure” and is the ultimate goal of antiviral therapy for chronic hepatitis B. In clinical practice, numerous studies have shown that the disappearance of HBsAg is the only indicator of good long-term outcomes for individuals with chronic HBV infection. In clinical practice, numerous studies have shown that prolonged courses of pegylated interferon therapy for chronic hepatitis B significantly improve HBeAg seroconversion and HBsAg disappearance rates. Lamprteico P et al. compared the persistent viral rates in patients with HBeAg-negative, genotype D chronic hepatitis B treated with pegylated interferon alpha-2a for 48 and 96 weeks at 24 weeks of treatment with a decrease in HBsAg levels greater than 10% and less than 10% at 1 year after discontinuation of the drug. The results showed that for patients with >10% reduction in HBsAg levels at 24 weeks of treatment, the sustained viral response rate at 48 weeks of treatment was only 17%, significantly lower than that at 96 weeks of treatment, which was 58%, while for patients with <10% reduction in HBsAg levels at 24 weeks of treatment, the sustained viral response rates at 48 and 96 weeks of treatment were 9% and 12%, respectively, and the results also showed that patients with good response on treatment, in order to obtain a higher treatment, there is a greater need to extend treatment. HBeAg-positive chronic hepatitis B (hepatitis B major triplet), female, 30 years old; found to be HBsAg positive for 5 years, married for many years, recently preparing for childbirth, had hepatoprotective treatment, no formal antiviral therapy, wish to have formal treatment. The patient had no history of antiviral treatment, but had been treated with hepatoprotective therapy and did not receive regular antiviral treatment. Treatment course The patient had no history of antiviral therapy, baseline ALT level was not very high but fluctuated repeatedly, and liver function was unstable after hepatoprotective therapy. HBV DNA was not very high, suggesting an active organism immune response, and the patient had a particularly strong desire to have children recently, hoping to stop the drug and get pregnant after obtaining better efficacy through interferon therapy. The patient was given pegylated interferon 180 μg once a week antiviral therapy, and after 3 months HBV DNA was below the lower limit of detection and liver function remained normal; surface antibodies appeared after 10 months; the patient's trend of continuous decline in HBsAg quantification during treatment was more obvious, and the patient was recommended to extend treatment to improve the chances of achieving HBsAg clearance and seroconversion. During the extended treatment, the patient's HBsAg continued to decline and HBsAb continued to rise. At 13 months of treatment, HBsAg 0.05 IU/L and HBsAb 32.8 mIU/ml achieved serological conversion of HBsAg. Due to the low antibody titer, the patient was recommended to continue treatment to consolidate treatment and discontinue treatment at 16 months of treatment with HBsAg 0.00 IU/L and HBsAb 523 mIU/ml. After six months of follow-up, the indexes were stable and the state of HBeAg serological conversion and HBsAg serological conversion was always maintained, and the lowest HBsAb was 322 mIU/ml. It is recommended to review regularly and to have a healthy baby safely and securely after six months of discontinuation. Which patients should consider extending the course of treatment? Patients who are close to surface antigen conversion but surface antibodies have not yet appeared Surface antigen positivity is a sign of hepatitis B virus infection, while the appearance of surface antibodies indicates that the hepatitis B virus is completely cleared and the patient is likely to be completely cured. Surface antigen conversion and surface antibody conversion are the ultimate or ideal goals of hepatitis B antiviral therapy. Studies have reported that 3-5% of patients treated with pegylated interferon for one year achieve these goals, which is the highest of all antiviral drugs. When patients have received the standard regimen for one year but are nearing conversion of surface antigen and surface antibodies have not yet emerged, an appropriate extension of the regimen is valuable and surface antigen/surface antibody conversion may be possible. Patients with e antigen near conversion e antigen positivity is a criterion for active viral replication and infectiousness, and liver function is not easily stabilized, allowing e antigen to convert to negative and e antibody to positive (commonly known as major triplet to minor triplet) is a satisfactory treatment goal for most patients receiving antiviral therapy. This goal is achieved in 30-40% of patients treated with pegylated interferon for 1 year, and further extension of the course of therapy may increase this percentage. Some patients present with near-negative e antigen conversion, when e antibodies may have been produced, but at lower titers that have not yet been detected. Extended therapy in such patients is likely to increase e antibody titers and achieve e antigen serologic conversion, laying the foundation for the pursuit of higher goals. Patients not on full dose for other reasons Because interferon has certain adverse effects such as fever, decreased white blood cells or platelets, muscle and bone aches, etc., a few patients need to have their dosage reduced because they cannot tolerate these adverse effects, and some patients have relative contraindications to interferon use (diabetes, hyperthyroidism, etc.) and urgently need treatment. In these patients, it is difficult to achieve satisfactory efficacy during the standard one-year course of treatment due to insufficient dose, and therefore an appropriate extension of the course of treatment is required. In particular, patients with high ALT and low HBV DNA at baseline have a higher chance of achieving HBeAg serological conversion or even clinical cure, i.e. HBsAg clearance, with pegylated interferon therapy, so pegylated interferon therapy can be considered for such patients. With pegylated interferon therapy, if a long-term virological response is obtained, or if serological conversion of e or s antigens is obtained at the same time, it will lead to clinical cure and long-term benefit for the patient. Changes in HBsAg quantification can help determine long-term outcomes, and patients with more significant decreases in HBsAg quantification during treatment are expected to have better outcomes. The patient started treatment with pegylated interferon and there was a significant decrease in the virus, but not below the detection line, and there were fluctuations in HBeAg and a continuous decrease in HBsAg, which gave us confidence to continue the prolonged treatment. We recommend full communication with the patient and the necessary quantitative hepatitis B five tests and DNA testing, sometimes even liver puncture. For patients who have completed one year of treatment, the choice of whether to extend the course of treatment is made in the context of their treatment status and financial conditions.