Predictors of adherence and virologic outcome in HIV-infected patients treated with abacavir- or indinavir-based triple combination HAART also containing lamivudine/zidovudine.
OBJECTIVE
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 IDV/COM group reported > or = 95% adherence to therapy (76 vs 58%, p < 0.001) and no difficulty in taking their regimen (91 vs 61%, p < 0.001). In both groups, the highest probability of HIV-1 RNA < 400 copies/mL occurred when median adherence was > or = 95%. The probability of HIV-1 RNA < 400 copies/mL declined more rapidly in the IDV/COM group as adherence rates decreased. LRA showed that no difficulty taking any of the drugs in the regimen, ABC/COM treatment group, and male gender were independent significant predictors of > or = 95% adherence (p < 0.05). Median adherence and baseline HIV-1 RNA were significant predictors of HIV-1 RNA < 400 copies/mL (p < 0.05).


CONCLUSIONS
Patients reported greater ease of use and superior adherence to ABC/COM than IDV/COM. Patient-reported difficulty taking drugs in a regimen was predictive of reduced adherence, and both of the latter factors were predictive of poorer virologic outcome. Adherence levels of > or = 95% in both treatment groups maximized the probability of patients achieving an HIV-1 RNA < 400 copies/mL.
Cahn
Pedro
P
Fundación HUESPED, Buenos Aires, Argentina.
Vibhagool
Asda
A
Schechter
Mauro
M
Soto-Ramirez
Luis
L
Carosi
Giampiero
G
Smaill
Fiona
F
Jordan
Jamie C
JC
Pharo
Cristina E
CE
Thomas
Nicola E
NE
Steel
Helen M
HM
D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D015224:Dideoxynucleosides / Q000008:administration & dosage / Q000627:therapeutic use*; D004338:Drug Combinations; D004359:Drug Therapy, Combination; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D019469:Indinavir / Q000008:administration & dosage / Q000627:therapeutic use*; D019259:Lamivudine / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D010349:Patient Compliance; D018894:Reverse Transcriptase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D012307:Risk Factors; D016896:Treatment Outcome; D015215:Zidovudine / Q000008:administration & dosage / Q000627:therapeutic use*; D000099227:Abacavir
D015224:Dideoxynucleosides; D004338:Drug Combinations; D017320:HIV Protease Inhibitors; D019469:Indinavir; D019259:Lamivudine; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D000099227:Abacavir