Assumption | How they were addressed and rationale |
---|---|
Recruitment of B Positive participants | Target population age ≥ 35, HBsAg + ve for ≥ 6 months, born in China, Hong Kong, Vietnam |
Contact testing and immunisation | Not factored into the model |
Seroprevalence data in target populations | Data provided by Nguyen et al [19] |
 |    • 10.7% for people born in China |
 |    • 10.5% for people born in Vietnam |
 |    • 7.7% for people born in Hong Kong |
Initial testing to confirm CHB | Not factored in GP consultation calculations |
Program participation rates | Base case assumption is 25% of eligible people enrolled |
Follow up requirements |    • Routine surveillance arm: 2 GP appointments/year |
 |    • Enhanced HCC surveillance arm: 2 GP appointments/year |
 |    • Interferon treatment: 6 specialist appointments/year |
 |    • Entecavir treatment (includes those with liver failure): 4 specialist appointments/year |
 |    • Patients with HCC: assumed monthly follow up |
Viral load distribution by age | Based upon REVEAL study, [22] as participant profile largely matches that of B Positive participants |
ALT cut-off levels | ALT≥ 1.5 × ULN triggers further evaluation in the absence of clinical data; ULN differentiated by participant age |
Progression rates through disease stages | Constant over time |
Patients with high VL and abnormal liver function | 30% receive first line interferon for 12 months |
 |    • 30% seroconvert and receive no further treatment |
 |    • 70% commence entecavir the following year |
 | 70% receive entecavir as first-line treatment |
 |    • 20% seroconvert in the first year of entecavir treatment and receive no further treatment |
 |    • 80% continue lifelong entecavir |
Patients with liver failure | All receive entecavir |