Objectives: To compare dosing convenience and adherence with abacavir (ABC) 300 mg plus a fixed-dose lamivudine 150 mg/zidovudine 300 mg combination tablet (COM) twice daily versus indinavir (IDV) plus COM twice daily in treatment- naïve, HIV-1-infected adults; and to evaluate the association among difficulty taking antiretroviral regimens, adherence, and virologic efficacy. Methods: An open-label, randomized, multicenter, international study compared the COM/ABC and IDV/COM regimens with respect to self-reported adherence and regimen convenience over 48 weeks. Logistic regression analysis (LRA) was done on a patient sub-sample from both groups to evaluate predictors of adherence and virologic response at last time-point on randomized therapy (LTORT). Results: The study population was diverse with respect to ethnicity (38% Asian, 27% Hispanic, 28% white, 3% black, 4% other) and gender (39% women, 61% men). Baseline median HIV-1 RNA was 4.80 log 10 copies/mL and CD4+ cell count was 315 cells/mm 3 . Of 329 patients who were randomized and received treatment, 315 (96%) provided adherence data. Significantly more patients in the ABC/COM group than in the SUMMARY ORIGINAL ARTICLE Predictors of adherence and virologic outcome in HIV-infected patients treated with abacavir- or indinavir-based triple combination HAART also containing lamivudine/zidovudine Pedro Cahn 1 , Asda Vibhagool 2 , Mauro Schechter 3 , Luis Soto-Ramirez 4 , Giampiero Carosi 5 , Fiona Smaill 6 , Jamie C. Jordan 7 , Cristina E. Pharo 8 , Nicola E. Thomas 9 and Helen M. Steel 8 1 Fundación ‘HUESPED’, Buenos Aires, Argentina; 2 Ramathibodi Hospital Mahidol University, Bangkok, Thailand; 3 Hospital Universitario Clemintino Fraga Filho, Rio de Janeiro, Brazil; 4 Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, Mexico; 5 Istituto di Malattie Infettive e Tropicali, Università degli Studi di Brescia, Italy; 6 McMaster University Medical Centre, Hamilton, Ontario, Canada; 7 Global Health Outcomes, Infectious Diseases, GlaxoSmithKline, Research Triangle Park NC, USA; 8 HIV and Opportunistic Infections Group, Glaxo Wellcome Research and Development, Greenford, UK; 9 Biomedical Data Sciences, GlaxoSmithKline Research and Development, Greenford, UK Address for correspondence: Dr Jamie C. Jordan, Manager, Global Health Outcomes, GlaxoSmithKline, Sanders 17.2124, Research Triangle Park, NC 27709, USA. Tel.: +1-919-483-5143; email: jamie.c.jordan@gsk.com Key words: Abacavir – Adherence – Combination antiretroviral therapy – Combination tablet – Indinavir – Lamivudine/zidovudine Paper 2572 1115 CURRENT MEDICAL RESEARCH AND OPINION® VOL. 20, NO. 7, 2004, 1115–1123 © 2004 LIBRAPHARM LIMITED 0300-7995 doi:10.1185/030079904125004051