Figure 1.

Study flow diagram. Selection of patients for analysis, from a cohort of patients initiating first-line, nonnucleoside reverse transcriptase inhibitor–based antiretroviral therapy between 1 January 2003 and 31 December 2008. Abbreviations: ART, antiretroviral therapy; PI, protease inhibitor; VL, viral load. ¹Patients with clustering on phylogenetic analysis were also excluded from having drug concentrations measured. One patient had insufficient sample to perform genotyping; however, after genotyping was performed, an additional 44 patients had insufficient samples available for measurement of drug concentrations.