Inclusion Criteria:
* Have participated in the "Zhufeng Project" with complete clinical data available.
* Aged between 18 and 65 years old, inclusive.
* Meet one of the following group-specific criteria:
Group 1: Functional Cure Group：
* Subjects in the functional cure group are individuals with a well-documented history of chronic hepatitis B (HBsAg-positive for ≥6 months) who have achieved functional cure following antiviral therapy.
* Inclusion criteria for this group:
* All antiviral therapies have been discontinued, and the off-treatment follow-up period from treatment discontinuation to the screening visit is no less than 24 weeks;
* Sustained post-treatment response during this period, operationally defined as confirmed HBsAg negativity (quantitative assay \<0.05 IU/mL) at or after Week 24 post-treatment discontinuation, plus persistently undetectable HBV DNA (\<10 IU/mL) by high-sensitivity PCR assay from treatment cessation through screening;
* Alanine aminotransferase (ALT) level ≤ upper limit of normal (ULN) at screening.
Group 2: Non-cured Group (active comparator group for this study)：
* The non-cured group serves as the active comparator and consists of participants with chronic hepatitis B receiving long-term effective antiviral treatment.
* Eligibility criteria:
* Receiving stable monotherapy with nucleos(t)ide analogs (NAs), with a total treatment duration of no less than 52 weeks. "Stable treatment" is defined as no regimen modification within the 24 weeks prior to screening;
* Sustained virological suppression: documented HBV DNA below the lower limit of detection (\<20 IU/mL) on at least two occasions (interval \>12 weeks) within the 24 weeks before screening;
* Persistently positive HBsAg (\>0.05 IU/mL) at screening;
* ALT level ≤ upper limit of normal (ULN) at screening.
Group 3: Healthy Control Group：
* The healthy control group provides normative baseline data for quality-of-life assessments. Eligible participants must be seronegative for all HBV serological markers (i.e., negative for HBsAg, anti-HBc, and HBV DNA), and have no known history of acute or chronic liver diseases.
* Individuals with malignancy, severe cardiovascular or cerebrovascular diseases, psychiatric disorders, or other major systemic diseases that may independently affect quality of life are excluded. To minimize confounding from demographic variables, this group will be frequency-matched to the prior two groups by age (±5 years), sex, and educational level. All enrolled subjects must have ALT levels within the normal range at screening.
Group 4: Relapse Group：
* Participants who previously fulfilled all eligibility criteria of the Functional Cure Group but developed virological relapse during off-treatment follow-up, defined as reversion from HBsAg-negative to HBsAg-positive status, and/or HBV DNA becoming detectable after being below the limit of detection.
* Provide written informed consent for study participation.
Exclusion Criteria:
* Presence of decompensated liver cirrhosis, hepatocellular carcinoma, or other malignant tumors.
* Co-infection with HIV, HCV, or HDV.
* Suffering from severe uncontrolled psychiatric disorders (e.g., schizophrenia, major depressive episode) or dementia.
* Presence of other chronic diseases that severely impair quality of life (e.g., end-stage renal disease, severe heart failure, etc.).
* Other conditions deemed ineligible for participation in this study by the investigator(s).
