Salvage Therapy with Adefovir Is Cost-Effective in Chronic
Hepatitis B

Current treatment options in chronic Hepatitis B (CHB) are limited in long-term efficacy. Interferon (INF) has significant side effects and lamivudine, though safe, is associated with a high rate of viral resistance. In contrast, adefovir is effective regardless of HepBeAg status.

However, adefovir is more expensive than competing therapies. A hybrid strategy with up-front lamivudine followed by "adefovir salvage" upon development of resistance may be a viable option. I this study, researchers sought to determine whether this salvage strategy is cost-effective versus lamivudine or IFN monotherapy in CHB.

Decision analysis with Markov modeling was used to calculate the cost-effectiveness of 3 strategies for the treatment of a cohort of 40 year old patients with CHB, elevated liver enzymes, and no cirrhosis (77% HepBeAg +):

(1)  INF 5 MU 3 times/week for 6 & 12 months for HepBeAg positive and negative patients respectively;

(2)  Lamivudine 100 mg/day with discontinuation upon sustained virological response (SVR) only;

(3)  Lamivudine 100 mg/day followed by 10 mg/day adefovir salvage therapy if resistance develops (salvage strategy).

Probability estimates were derived from a systematic review of the literature and were widely varied in sensitivity analysis. Cost estimates for treatment costs and long-term outcomes (including cirrhosis and related complications) were performed from a third party payer perspective and were obtained from Medicare and the Red Book. The primary outcome measure was cost per life year (LY). Both costs and LYs were discounted at 3%/year.

Results

The lifetime average cost/patient for the INF, lamivudine and adefovir salvage strategies were $18,607, $20,915, and $28,362 respectively. The INF and lamivudine strategies provided 34.7 and 37.2 undiscounted LYs respectively.

The adefovir salvage strategy was most effective as it provided 38.9 LYs. With discounting, the use of adefovir salvage strategy instead of lamivudine cost an incremental $14,204 to gain one additional LY.

Adefovir salvage became the dominant strategy when the cost of adefovir was <$300/month (base-case=$528), the cost of lamivudine was >$305/month (base-case=$158), and when >60% of the cohort was HepBeAg negative.

The authors conclude, “Adefovir salvage therapy is more effective than both INF and lamivudine monotherapy at an acceptable incremental cost. The salvage strategy becomes the preferred approach overall in patients with HepBeAg negative CHB, suggesting a possible key role in the management of this therapeutically resistant sub-group.”

05/17/04

Reference
Fasiha Kanwal Adefovir Salvage Therapy is Cost-Effective in Chronic Hepatitis B. Abstract 6. Digestive Disease Week 2004. May 15-20. New Orleans, LA.