Cardiovascular Events in an Inner-City HIV Clinic and Relationship to Abacavir Versus Tenofovir Disoproxil Fumarate-Containing Antiretroviral Regimens.

Following cardiovascular events (CVE) among people living with HIV (PLWH) is essential. Abacavir (ABC)'s impact on CVE challenges clinicians. We characterized CVE at our HIV clinic associated with ABC versus tenofovir disoproxil fumarate (TDF). This was a retrospective study of PLWH who started combination antiretroviral therapy with no prior CVE. Patients were evaluated as antiretroviral naive or antiretroviral experienced. Regimens included the following: always-ABC, always-TDF, first-ABC-switched-to-TDF, and first-TDF-switched-to-ABC regimens. Frequencies, rates, and Poisson regression were used to analyze CVE (cardiovascular/cerebrovascular) and were stratified with an a priori cutoff of before or after January 1, 2009. 1,440/2,852 patients were antiretroviral naive; 658 on always-ABC regimens, 1,186 on always-TDF regimens, 737 first-ABC-switched-to-TDF regimens, and 271 first-TDF-switched-to-ABC regimens. Seventy seven CVE occurred overall [16 naive vs. 61 experienced (p < .0001)]. Sixty events were cardiovascular and 17 cerebrovascular (p < .0001). Sixty-nine CVE occurred before 2009 and eight after (p < .0001). There were 5.65 CVE-per-1,000-years [95% confidence interval (CI) 3.23-9.87] in the always-ABC, 1.95 CVE-per-1,000-years (95% CI 1.08-3.51) in the always-TDF, 2.01 CVE-per-1,000-years (95% CI 1.14-3.56) in the ABC-switched-to-TDF, and 1.82 CVE-per-1,000-years (95% CI 0.77-4.30) in TDF-switched-to-ABC (p <.01). Multivariable Poisson regression incidence rate ratios (IRRs) revealed that being on ABC-only (IRR 2.89; 95% CI 2.13-3.94), age (IRR 1.06 per year; 95% CI 1.04-1.07), and smoking (IRR for current 2.81; 95% CI 1.97-3.99; IRR for former 2.49; 95% CI 1.72-3.61) increased risk of CVE. Thus, in our clinic, CVE rates were increased in those on ABC and adds to the body of literature suggesting concern.

Assessment of antiretroviral third agent virologic durability after initiation of first antiretroviral regimen.

Information on the virologic durability of modern antiretroviral regimens is important to clinicians. We aimed to describe virologic durability of first-line integrase strand transfer inhibitor (INSTI)-, nonnucleoside reverse transcriptase inhibitor (NNRTI)-, or protease inhibitor (PI)-based antiretroviral regimens. This was a retrospective study of antiretroviral-naïve patients that initiated first-line antiretroviral regimens with two nucleoside reverse transcriptase inhibitors and an INSTI, NNRTI, or PI between January 2006 and June 2016. The outcome was time to virologic failure, which was assessed by Kaplan-Meier survival analysis and Cox regression models. There were 780 patients (median age = 37 years [interquartile range (IQR) = 30-45], 93.3% male, 56.2% Caucasian, median HIV duration = 1.8 years [IQR = 0.4-5.4], baseline log10 viral load [VL]=4.6 [IQR = 4.1-5.1], and baseline CD4+ cell count = 320 cells/µl [IQR = 217-440]). In total, 189/780 were on a third agent INSTI, 339/780 on a third agent NNRTI, and 252/780 on a third agent PI. Kaplan-Meier survival probability revealed longer time to virologic failure for INSTI, followed by NNRTI then PI (p < 0.001). Multivariable Cox regression revealed that being on an INSTI regimen (aHR = 0.27; 95%CI = 0.18-0.41) or NNRTI regimen (aHR = 0.64; 95%CI = 0.47-0.87) versus PI regimen, frequent VL testing (per year), (aHR = 0.64; 95%CI = 0.47-0.87), and duration of ART (aHR = 0.22; 95%CI = 0.17-0.30) (years) were inversely associated with time to virologic failure, and log10 of baseline VL (aHR = 1.94; 95%CI = 1.58-2.39 per log10) increased risk. Virologic failure was delayed and virologic durability prolonged for INSTI- compared to NNRTI- and PI-based regimens, supporting current antiretroviral therapy guidelines.

Time to Viremia for Patients Taking their First Antiretroviral Regimen and the Subsequent Resistance Profiles.

BACKGROUND: The resistance profiles for patients on first-line antiretroviral therapy (ART) regimens after viremia have not been well studied in community clinic settings in the modern treatment era. OBJECTIVE: To determine time to viremia and the ART resistance profiles of viremic patients. METHODS: HIV-positive patients aged ≥16 years initiating a three-drug regimen were retrospectively identified from 01/01/06 to 12/31/12. The regimens were a backbone of two nucleoside reverse transcriptase inhibitors (NRTIs) and a third agent: a protease inhibitor (PI), non-nucleoside reverse transcriptase inhibitor (NNRTI), or an integrase inhibitor (II). Time to viremia was compared using a proportional hazards model, adjusting for demographic and clinical factors. Resistance profiles were described in those with baseline and follow-up genotypes. RESULTS: For 653 patients, distribution of third-agent use and viremia was: 244 (37%) on PIs with 80 viremia, 364 (56%) on NNRTIs with 84 viremia, and 45 (7%) on II with 11 viremia. Only for NNRTIs, time to viremia was longer than PIs (p = 0.04) for patients with a CD4 count ≥200 cells/mm(3). Of the 175 with viremia, 143 (82%) had baseline and 37 (21%) had follow-up genotype. Upon viremia, emerging ART resistance was rare. One new NNRTI (Y181C) mutation was identified and three patients taking PI-based regimens developed NRTI mutations (M184 V, M184I, and T215Y). CONCLUSIONS: Time to viremia for NNRTIs was longer than PIs. With viremia, ART resistance rarely developed without PI or II mutations, but with a few NRTI mutations in those taking PI-based regimens, and NNRTI mutations in those taking NNRTI-based regimens.

Time to virologic failure for patients taking their first antiretroviral regimen and the subsequent resistance profiles.

INTRODUCTION: The resistance profiles of first-line antiretroviral therapy (ART) regimens after virologic failure have yet to be studied in a clinic setting in the modern treatment era. Time to virologic failure among three standard first-line regimens and the resistance profiles of these failures were compared. MATERIALS AND METHODS: All HIV-positive persons aged 16 and over starting a three-drug first-line ART regimen were retrospectively identified at a Toronto community clinic (1 January 2006-1 January 2013). The regimens included a backbone of two NRTIs and a third agent; a PI, an NNRTI, or an II. Patients must have been on treatment for at least 14 days and have at least one VL test within 6 months after starting treatment. The primary outcome was virologic failure defined as either: no suppression by 6 months, or after suppression, two consecutive, detectable VL200 copies/mL at least 14 days apart or one VL>200 copies/mL. Time to failure was compared using a proportional hazards model adjusting for demographic and clinical factors. Resistance profiles of NRTIs and third agents are described in patients with virologic failure who had both baseline and virologic failure genotypes. RESULTS: Six hundred sixty patients (93% male) were included with a mean age of 38.9 and a median follow-up period of 35.3 (32.2-39.3) months. Distribution of third agent use was: PI 37.3% (n=246), NNRTI 55.9% (n=369) and II 6.8% (n=45). Virologic failures occurred in 81/246 (33%) with PI, 87/369 (24%) with NNRTI and 11/45 (24%) with II. Compare to PIs, time to failure was longer with NNRTIs (p=0.0013) and similar for IIs (p=0.1562). No evidence that failure with NNRTIs was different from IIs (p=0.9139). Of the 660 patients, 567 (86%) had a baseline genotype. Of the 567 patients, 179 had virological failure. Of the 179, 145(81%) had a baseline genotype and only 37 (21%) had both a baseline and follow-up genotype. Upon failure, emerging ART resistance was rare. No new PI or II mutations were identified and one new NNRTI (Y181C) mutation was identified. Three patients taking PI-based regimens developed NRTI mutations (M184V, M184I, T215Y). CONCLUSIONS: Time to virologic failure was significantly greater in the NNRTI group compared to the PI group. If failure did occur, ART resistance rarely developed with no PI mutations but a few NRTI mutations in those taking PI-based regimens, and NNRTI mutations in those taking NNRTI-based regimen.