Regimen-dependent variations in adherence to therapy and virological suppression in patients initiating protease inhibitor-based highly active antiretroviral therapy.
OBJECTIVE
To examine differences among four protease inhibitor (PI)-based drug regimens in adherence to therapy and rate of achievement of virological suppression in a cohort of antiretroviral-naive patients initiating highly active antiretroviral therapy (HAART).


METHODS
Participants were antiretroviral-naive and were first dispensed combination therapy containing two nucleosides and a ritonavir (RTV)-boosted PI, or unboosted nelfinavir, between 1 January 2000 and 30 September 2003. Logistic regression analysis was used to examine associations between the prescribed PI and other baseline factors associated with being >90% adherent to therapy and then to determine the associations of prescribed drug regimen, adherence to therapy and baseline variables with the odds of achieving two consecutive viral loads of <500 HIV-1 RNA copies/mL. RESULTS A total of 385 subjects were available for analysis. Lopinavir (LPV)/RTV was prescribed for 168 patients (42% of total); 86 (22%) received indinavir (IDV)/RTV; 91 (24%) received nelfinavir (NFV) and 40 (10%) received saquinavir (SQV)/RTV. SQV/RTV-based HAART was associated with reduced adherence to therapy [odds ratio (OR)=0.40; 95% confidence interval (CI) 0.19-0.83]. In multivariate models, IDV/RTV (OR=0.45; 95% CI 0.22-0.92), SQV/RTV (OR=0.18; 95% CI 0.07-0.43) and NFV were associated with reduced odds of achieving virological suppression within 1 year in comparison to LPV/RTV-based therapy. For patients receiving NFV, adjusting for adherence (OR=0.73; 95% CI 0.36-1.47) rendered this association nonsignificant.


CONCLUSIONS
Patients prescribed IDV/RTV, NFV or SQV/RTV were less likely to achieve virological suppression on their first regimen compared with patients prescribed LPV/RTV. Reduced adherence to these therapies only partly explained these observed differences.
Moore
D M
DM
BC Centre for Excellence in HIV/AIDS, Vancouver, British Columbia, Canada. dmoore@cfenet.ubc.ca
Hogg
R S
RS
Yip
B
B
Wood
E
E
Harris
M
M
Montaner
J S G
JS
D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D001955:British Columbia; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology; D017320:HIV Protease Inhibitors / Q000008:administration & dosage*; D015497:HIV-1; D006801:Humans; D061466:Lopinavir; D008297:Male; D019888:Nelfinavir / Q000008:administration & dosage; D010349:Patient Compliance; D011744:Pyrimidinones / Q000008:administration & dosage; D019438:Ritonavir / Q000008:administration & dosage; D019258:Saquinavir / Q000008:administration & dosage; D019562:Viral Load
D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D061466:Lopinavir; D019888:Nelfinavir; D019258:Saquinavir; D019438:Ritonavir