Optimizing treatment for patients with persistent lowlevel viremia is complicated because most genotyping tests are validated for viral loads .1000 copies per milliliter. In this study, genotypes of 92 treatment-experienced patients with persistent lowlevel viremia were determined using an in-house assay. Based on the resistance profiles obtained from genotyping and patient pharmacologic history, patients were either maintained on their antiviral regimen (n = 51) or received an optimized

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... (n = 41). In the group receiving optimized treatment, undetectable viral loads were achieved in 73.2% at 6 months and at 90.2% at 1 year, indicating that treatment guided by genotyping of patients with low-level viremia is effective in achieving viral suppression.