New antiretroviral agent use affects prevalence of HIV drug resistance in clinical care populations.

OBJECTIVE: To estimate the prevalence of HIV drug resistance over time and identify risk factors for multiclass resistance.

DESIGN: Prospective clinical cohort of HIV-infected patients at the University of North Carolina.

METHODS: Among antiretroviral therapy (ART)-experienced patients in care 2000-2016, we estimated annual prevalences of cumulative resistance, defined as at least one major mutation by drug class. Clinical data and multiple imputation were used when genotypic data were missing, and mutations were carried forward in time. We estimated resistance odds ratios comparing characteristics of patients in care in 2016.

RESULTS: A total of 3682 patients contributed 23 169 person-years. Prevalence of at least one major resistance mutation, irrespective of viral suppression, peaked in 2005 with 49% (95% confidence interval 46, 52) and decreased to 38% (35, 40) in 2016. Resistance to nucleoside reverse transcriptase inhibitors, protease inhibitors, and nonnucleoside reverse transcriptase inhibitors also peaked in 2005-2007 and decreased to 28 (26, 31), 14 (12, 16), and 27% (24, 29) in 2016, respectively. In 2016, prevalence of integrase strand transfer inhibitor (INSTI) resistance was 2% (1, 3) and triple-class resistance 10% (9, 12). Over the study period, cumulative resistance was frequent among patients with detectable viremia, but uncommon among patients initiating ART post-2007. Among 1553 patients in care in 2016, ART initiation at an older age, with an INSTI, and with higher CD4 cell counts were associated with resistance to fewer or no classes.

CONCLUSION: Prevalence of resistance to older ART classes has decreased in the last 10 years in this clinical cohort, whereas INSTI resistance has increased but remained very low. Patients with viremia continue to have a high burden of resistance even if they initiated ART recently.