The cost-effectiveness of highly active antiretroviral therapy, Canada 1991–2001 Eduard J. Beck a,b , Sundhiya Mandalia c , Maurice Gaudreault a , Carl Brewer b , Hanna Zowall b , Norbert Gilmore b,d , Marina B. Klein b,d , Richard Lalonde b,d , Alain Piche ´ e and Catherine A. Hankins a,b Aim: To estimate the cost-effectiveness ratio of highly-active antiretroviral therapy (HAART) in Canada. Design: A before-and-after analysis to calculate incremental cost of life year gained (LYG) between 1991 and 1995 (pre-HAART period) and between 1997 and 2001 (HAART period) for non-AIDS and AIDS groups (CDC stage of HIV infection). Methods: For two Quebec HIV hospital clinics, mean inpatient (IP) days, outpatient (OP) visits and direct health care costs per patient-year (PPY) were calculated. Cox’s proportional hazards models calculated disease progression, stratified by study periods and adjusted for gender, age at cohort entry, sexual orientation, injecting drug use and baseline CD4 cell count. Results: For non-AIDS patients, mean IP days was 1.6 (pre-HAART period) compared with 0.8 PPY (HAART period); mean OP visits increased from 2.8 to 5.5 PPY. Total cost was US$ 4265 (pre-HAART period) and US$ 9445 PPY (HAART period) of which 66 and 84%, respectively were spent on antiretroviral drugs. Median progression time was 6.3 years in the pre-HAART period compared with 12.5 years in HAART period (log rank ÷ 2 ¼ 270, P , 0.0001). Incremental cost per LYG between periods was US$ 14 587. For AIDS patients, mean IP days decreased from 13.3 to 4.4 PPY between periods; OP visits increased from 8.3 to 9.2 PPY. Total costs increased from US$9099 to US$ 11 754 PPY, while expenditure on antiretroviral drugs increased from 29 to 72% of total cost. Median progression time was 3.8 years in the pre-HAART period, which increased to 13.3 years in the HAART period (log rank ÷ 2 ¼ 158, P , 0.0001); incremental cost per LYG between periods was US$ 12 813. Conclusion: HAART appeared a cost-effective intervention in Canada. & 2004 Lippincott Williams & Wilkins AIDS 2004, 18:2411–2418 Keywords: use and costs services, cost-effectiveness, highly active antiretroviral therapy, life year gained, CDC stage of HIV infection Introduction The efficacy of triple combination antiretroviral ther- apy (ART) was first reported during the XI Interna- tional Conference on AIDS in Vancouver in 1996 [1]. By 1997 highly active antiretroviral therapy (HAART) was the new standard of HIV treatment and care and introduced into routine clinical care in Canada. There From the a Departement de sante publique de Montre ´al-centre, Quebec, the b Joint Departments of Epidemiology, Biostatistics and Occupational Health McGill University, Quebec, Canada, the c St. Stephen’s Centre, Chelsea & Westminster Hospital, Imperial College, London, UK, the d Immunodeficiency Service, Institut thoracique de Montre ´al, McGill University Health Centre, Quebec, Canada and e Centre Universitaire de Sante ´ de l’Estrie, Quebec, Canada. Correspondence to Dr E. J. Beck, Strategic Information and Research (SIR) Unit, HIV Department, HIV-Tuberculosis - Malaria Cluster, World Health Organization, 20 avenue Appia, 1211 Geneva 27, Switzerland. E-mail: becke@who.int or eduard.beck@mcgill.ca Received: 30 May 2004; revised: 24 August 2004; accepted: 14 September 2004. ISSN 0269-9370 & 2004 Lippincott Williams & Wilkins 2411