Third International Congress Drug Therapy in HIV Infection 3-7 November 1996 Glasgow, UK

MODELLING THE COST-EFFECTIVENESS OF EPIVIR (3TC™) / RETROVIR™ (ZIDOVUDINE) COMBINATION THERAPY IN HIV INFECTION

NM Chancellor¹, AM Hill², CA Sabin³, KN Simpson⁴ and M Youles^5
1Glaxo Wellcome UK Ltd, Uxbridge, Middlesex; ²Glaxo Wellcome Research and Development Ltd, Greenford, Middlesex; ³Department of Primary Care and Population Sciences, Royal Free Hospital, London; ⁴University of North Carolina, Chapel Hill, NC; ⁵HIV/GUM Research Unit, Chelsea and Westminster Hospital, London

Int Cong Drug Therapy HIV 1996 Nov 3-7;3:Abstract No. SS2.3
AIDS 1996, Vol. 10 (Suppl. 2);S10

The use of combination anti-retroviral therapy is supported by clinical evidence for its superiority over monotherapy. 3TC has been studied in combination with ZDV and is recommended for use specifically in combination therapy. With the associated increase in drug acquisition cost, the economics of combination therapy versus monotherapy warrants study. An economic evaluation was undertaken to compare 3TC/ZDV with ZDV, taking a UK public finance perspective.

The cost-effectiveness of each of the two treatments was estimated using a Markov model of progression through three HIV-positive disease states: a) 200<CD4<500, b) CD4<200, non-AIDS, c) AIDS to eventual death. Progression probabilities and life expectancy were derived from a cohort treated at Chelsea and Westminster Hospital, using data for 1987-95, along with cost data for a ZDV intent-to-treat population for 1994/95. The relative risk (RR) of progression for 3TC/ZDV compared to ZDV was estimated from meta-analysis of all four completed comparative trials. To predict the effect of 3TC/ZDV on life expectancy and lifetime costs, progression probabilities were adjusted by the RR statistic for the duration of treatment with 3TC/ZDV.

Based on an estimated RR of progression of 0.509 (95% CI 0.365-0.710), treatment with 3TC/ZDV is predicted to yield an incremental cost-effectiveness ratio of circa £6,500 per life year saved (discounted @ 6%). Extensive sensitivity analyses were performed to test the effects of varying values of input parameters on the model results. Under reasonable assumptions, the predicted cost-effectiveness of 3TC/ZDV combination therapy compares favourably with previously reported economic analyses of various HIV treatments¹.

1. KN Simpson. Design and assessment of cost-effectiveness studies in AIDS populations. J Acquir Immune Defic Syndr Hum Retrovirol. 1995;10 Suppl 4:S28-32.

Epivir™, 3TC™ and Retrovir™ are trademarks of the Glaxo Wellcome group of companies.

Presenting author: NM Chancellor

1996-11-03
SS2.3

Originally published in AIDS Volume 10, Supplement 2 and hosted with permission of the publisher Lippincott Williams & Wilkins, 250 Waterloo Road, London, SE1 8RD, UK. Tel: +44 (0)20 7981 0700 Fax: +44 (0) 7981 0701

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