Author(s): Harrigan PR, Hogg RS, Dong WW, Yip B, Wynhoven B,
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Abstract OBJECTIVE: The objective of this study was to systematically characterize the incidence and determinants of antiretroviral resistance in the HOMER (Highly Active Antiretroviral Therapy [HAART] Observational Medical Evaluation and Research) cohort of 1191 human immunodeficiency virus-infected, antiretroviral-naive adults initiating HAART in British Columbia, Canada. METHODS: All plasma samples with plasma virus loads (pVLs) >1000 copies/mL collected during the first 30 months of follow-up were genotyped for drug resistance. The primary outcome measure was time to the first detection of major drug-resistance mutation(s). Cox proportional hazard regression was used to identify factors significantly associated with the detection of drug-resistance mutations. RESULTS: Drug-resistance mutations were detected in 298 subjects (25\%). Factors significantly associated with detection of drug-resistance mutations included high baseline pVL (multivariate hazard ratio [HR], 1.59; P<.001) and adherence (estimated using prescription-refill data and/or untimed plasma drug-concentration measurements). When compared with subjects with low (0\%-<20\%) prescription-refill percentages, subjects at an elevated risk of harboring drug-resistance mutations were those with relatively high but imperfect prescription-refill percentages (80\%-<90\%; multivariate HR, 4.15; P<.001) and those with essentially perfect (>/=95\%) refill percentages but with 2 plasma drug concentrations below the steady-state trough concentration minus 1 standard deviation (multivariate HR, 4.57; P<.001). Initial use of nonnucleoside reverse-transcriptase inhibitor-based HAART was significantly associated with multiclass drug resistance (multivariate HR, 1.84; P=.001). CONCLUSION: High baseline pVLs and substantial but imperfect levels of adherence were major predictors of antiretroviral resistance.
This article was published in J Infect Dis
and referenced in Journal of AIDS & Clinical Research