Analytical approach:
A decision analytic Markov model was developed to assess the cost-effectiveness of the different treatment strategies. Due to differences in the age profile of patients who were hepatitis B antigen e positive and those who were negative, the model was run separately for each of these subgroups. The time horizon was 40 years. The perspective was that of the Brazilian national health system.
Effectiveness data:
Effectiveness data were derived from a previously published systematic review (Almeida et al. 2009, see Other Publications of Related Interest) and a review of selected studies. The main clinical effectiveness estimates were HBeAg (hepatitis B e antigen) seroconversion rates, treatment response rates and relapse rates associated with the three interventions. These estimates were derived from published studies.
Monetary benefit and utility valuations:
None.
Measure of benefit:
The benefit measure was life-years gained discounted at an annual rate of 5%.
Cost data:
The direct costs included in the analysis were those related with: medication therapies, and treatment of chronic hepatitis B complications (including medical fees, examinations, diagnostic and therapeutic procedures, hospitalisations and medications). Hepatitis B treatment costs were derived from published study (Castelo et al. 2007, see Other Publications of Related Interest) that evaluated the chronic hepatitis B costs in Brazil with a Delphi panel of specialists. Medication therapy costs were based on medication prices from the Brazilian Medication Market Regulating Chamber. All costs were updated to 2009 prices. All costs were converted from Brazilian real (BRL) to USA dollars adjusted for purchasing power parity ($) and discounted at an annual rate of 5%.
Analysis of uncertainty:
A series of one-way sensitivity analyses were carried out by varying therapy response, price of medication, discount rates and treatment effectiveness. Results were presented in a Tornado diagram. A probabilistic sensitivity analysis was conducted with results presented in a cost-effectiveness acceptability curve.