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COST-EFFECTIVENESS OF ADDING IN ADEFOVIR FOLLOWING CLINICAL OR VIROLOGIC RESISTANCE TO LAMIVUDINE IN CIRRHOTIC HEPATITIS B PATIENTS
HA Dakin1, T Barwell1, M Sherman2, E Yoshida3, E Gudaitis4, B Canestraro4, V Popovic4
1Abacus International, Oxfordshire, UK; 2Toronto General Hospital, Toronto, ON; 3Vancouver General Hospital, Vancouver, BC; 4Gilead Sciences, Mississauga, ON
BACKGROUND: A recent cohort study in cirrhotic hepatitis B patients demonstrated that adding adefovir (ADV) to ongoing lamivudine (LAM) therapy at the time of virologic resistance to LAM (e.g. raised HBV DNA levels) reduced the risk of hepatic decompensation, liver transplantation and death relative to adding ADV when clinical signs of LAM resistance appear (e.g. raised ALT) or continuing LAM monotherapy. Based on this study, we set out to assess the cost-effectiveness of adding ADV to LAM when virologic LAM resistance develops (“ADVvir”) relative to adding in ADV when clinical resistance develops (“ADVclin”) and continuing LAM monotherapy (“LAM only”) in patients with hepatic cirrhosis associated with chronic hepatitis B infection. The perspective of the analysis was the publicly-funded healthcare system in Canada.
METHODS: A Markov model was constructed to model disease progression and calculate costs and benefits over a 50-year period. Patients in the ADVvir arm were assumed to be screened annually for LAM resistance mutations. Utilities and disease management costs were obtained from the literature, while costs of drugs and screening/monitoring tests were based on Canadian tariffs. Costs and benefits were discounted at 5% per year.
RESULTS: The average patient in the ADVvir arm experienced a total of 6.0 quality-adjusted life-years (QALYs) after the point at which LAM resistance developed, compared with 1.9 QALYs/patient in the LAM-only arm and 4.9 in the ADVclin arm. Including screening costs of $40.34 per patient, the ADVvir arm was associated with lifetime treatment costs of $222,434 per patient, compared with $222,604 for the ADVclin arm and $72,864 for the LAM only arm. ADVvir therefore dominated ADVclin, saving $170 and gaining 1.2 QALYs per patient treated. ADVvir cost $36,191 per QALY gained relative to LAM only, while ADVclin cost $50,356/QALY relative to LAM. Sensitivity analyses showed that the results are robust.
CONCLUSIONS: This analysis demonstrates that it is cost-effective to monitor for LAM resistance and add in ADV to ongoing LAM therapy in patients with compensated cirrhosis as soon as virologic signs of LAM resistance develop.
This study was funded by Gilead Sciences Canada