Resistance profiles and adherence at primary virological failure in three different highly active antiretroviral therapy regimens: analysis of failure rates in a randomized study

Detection of Gag C-terminal mutations among HIV-1 non-B subtypes in a subset of Cameroonian patients

Response to ritonavir-boosted-protease inhibitors (PI/r)-based regimen is associated with some Gag mutations among HIV-1 B-clade. There is limited data on Gag mutations and their covariation with mutations in protease among HIV-1 non-B-clades at PI/r-based treatment failure. Thus, we characterized Gag mutations present in isolates from HIV-1 infected individuals treated with a PI/r-regimen (n = 143) and compared them with those obtained from individuals not treated with PI/r (ART-naïve [n = 101] or reverse transcriptase inhibitors (RTI) treated [n = 118]). The most frequent HIV-1 subtypes were CRF02_AG (54.69%), A (13.53%), D (6.35%) and G (4.69%). Eighteen Gag mutations showed a significantly higher prevalence in PI/r-treated isolates compared to ART-naïve (p < 0.05): Group 1 (prevalence < 1% in drug-naïve): L449F, D480N, L483Q, Y484P, T487V; group 2 (prevalence 1–5% in drug-naïve): S462L, I479G, I479K, D480E; group 3 (prevalence ≥ 5% in drug-naïve): P453L, E460A, R464G, S465F, V467E, Q474P, I479R, E482G, T487A. Five Gag mutations (L449F, P453L, D480E, S465F, Y484P) positively correlated (Phi ≥ 0.2, p < 0.05) with protease-resistance mutations. At PI/r-failure, no significant difference was observed between patients with and without these associated Gag mutations in term of viremia or CD4 count. This analysis suggests that some Gag mutations show an increased frequency in patients failing PIs among HIV-1 non-B clades.

Prevalence of human immunodeficiency virus-1 drug-resistant mutations among adults on first- and second-line antiretroviral therapy in a resource-limited health facility in Busia County, Kenya

Introduction

in Kenya, about 1.5 million people are living with the Human Immunodeficiency Virus (HIV). Antiretroviral therapy aids in viral suppression. However, drug-resistance threaten the gains of the HIV infection control program. To determine the prevalence of HIV-1 drug-resistant mutations among adults on ARV therapy attending Khunyangu sub-county hospital in Busia County, Kenya, 50 blood samples were analyzed.

Methods

the samples were collected from November 2019 to January 2020 and tested for HIV-1 viral load. HIV-1 drug-resistance was analyzed through the sequencing of the HIV-1 pol gene. Generated sequences were aligned using RECall (beta v3.05) software. HIV-1 drug-resistance was determined using the Stanford University HIV database.

Results

females were 34 and males 16. The general prevalence of HIV-1 drug-resistance was 68%. Out of 34 participants on first-line drugs, 59.9% had mutations against these drugs and 5.9% against the second-line drugs. Out of 16 participants on second-line drugs, 43.8% had mutations against these drugs and 50% against the first-line drugs. The prevalence of mutations encoding resistance to Nucleotide reverse transcriptase inhibitors (NRTIs) were 23(46%); Non-nucleotide Reverse transcriptase inhibitors (NNRTIs), 29(58%) and protease inhibitors (PIs), 7(14%). Dual and multi-class HIV-1 drug-resistance prevalence was as follows: NRTIs + NNRTIs 16(32%); NRTIs + NNRTs + PIs 4(8%); NRTIs + PIs 1(2%). A total of 126 mutations were identified. Predominant NNRTIs mutations were K103N (15), Y181C (9), G190A (7), and H221Y (6) NRTIs, M184V (17), Y115F (5) and PIs, I54V (4).

Conclusion

the study demonstrates a high prevalence of HIV-1 drug-resistance which calls for intervention for the strengthening of health programs.

Gag P2/NC and pol genetic diversity, polymorphism, and drug resistance mutations in HIV-1 CRF02_AG- and non-CRF02_AG-infected patients in Yaoundé, Cameroon

In HIV-1 subtype-B, specific mutations in Gag cleavage sites (CS) are associated with treatment failure, with limited knowledge among non-B subtypes. We analyzed non-B HIV-1 gag and pol (protease/reverse-transcriptase) sequences from Cameroonians for drug resistance mutations (DRMs) in the gag P2/NC CS, and pol major DRMs. Phylogeny of the 141 sequences revealed a high genetic diversity (12 subtypes): 67.37% CRF02_AG versus 32.6% non-CRF02_AG. Overall, 7.3% transmitted and 34.3% acquired DRMs were found, including M184V, thymidine analogue mutations (T215F, D67N, K70R, K219Q), NNRTIs (L100I, Y181C, K103N, V108I, Y188L), and PIs (V82L). Twelve subjects [10 with HIV-1 CRF02_AG, 8 treatment-naïve and 4 on 3TC-AZT-NVP] showed 3 to 4 mutations in the Gag P2/NC CS: S373Q/T/A, A374T/S/G/N, T375S/A/N/G, I376V, G381S, and R380K. Subjects with or without Gag P2/NC CS mutations showed no significant difference in viral loads. Treatment-naïve subjects harboring NRTI-DRMs had significantly lower CD4 cells than those with NRTI-DRMs on ART (p = 0.042). Interestingly, two subjects had major DRMs to NRTIs, NNRTIs, and 4 mutations in the Gag P2/NC CS. In this prevailing CRF02_AG population with little exposure to PIs (~3%), mutations in the Gag P2/NC CS could increase the risk of treatment failure if there is increased use of PIs-based therapy.

Burden of nonnucleoside reverse transcriptase inhibitor resistance in HIV-1-infected patients: a systematic review and meta-analysis

The prevalence of HIV drug resistance varies with geographic location, year, and treatment exposure. This study generated yearly estimates of nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance in treatment-naive (TN) and treatment-experienced (TE) patients in the United States (US), Europe (EU), and Canada. Studies reporting NNRTI resistance identified in electronic databases and 11 conferences were analyzed in three groups: (1) TN patients in one of four geographic regions [US, Canada, EU countries with larger surveillance networks ("EU1"), and EU countries with fewer data ("EU2")]; (2) TE patients from any region; and (3) TN patients failing NNRTI-based treatments in clinical trials. Analysis data included 158 unique studies from 22 countries representing 84 cohorts of TN patients, 21 cohorts of TE patients, and 8 trials reporting resistance at failure. From 1995 to 2000, resistance prevalence in TN patients increased in US and EU1 from 3.1% to 7.5% and 0.8% to 3.6%, respectively. Resistance in both regions stabilized in 2006 onward. Little resistance was identified in EU2 before 2000, and increased from 2006 (5.0%) to 2010 (13.7%). One TN Canadian study was identified and reported resistance of 8.1% in 2006. Half of TN clinical trial patients had resistance after treatment failure at weeks 48-144. Resistance in TE patients increased from 1998 (10.1%) to 2001 (44.0%), then decreased after 2004. Trends in NNRTI resistance among TN patients show an increased burden in the US and some EU countries compared to others. These findings signify a need for alternate first-line treatments in some regions.

Suboptimal adherence associated with virological failure and resistance mutations to first-line highly active antiretroviral therapy (HAART) in Bangalore, India

This study was conducted to examine the relationship between adherence, viral load (VL) and resistance among outpatients receiving highly active antiretroviral therapy (HAART) in Bangalore, India. In total, 552 outpatients were recruited and VL testing was conducted for all study participants. HIV-1 genotypic resistance testing was performed for 92 participants with a VL ≥ 1000 copies/ml. Interpretation of resistance mutations was performed according to the Stanford database. Past-month adherence and treatment interruptions for >48 h were assessed via self-report. At baseline, 34 participants (6%) reported <95% past-month adherence and 110 (20%) reported a history of >48 h treatment interruptions. Combining the two adherence measures, 22% of participants were classified as 'suboptimally adherent'. In total, 24% of study participants (n = 132) had a detectable VL. Among the 92 samples sent for resistance testing, 68% had at least one nucleoside reverse transcriptase inhibitor (NRTI) mutation, with M184V being the most common (62%) and with 48% having thymidine analogue mutations. Moreover, 72% had at least one non-nucleoside reverse transcriptase inhibitor (NNRTI) mutation and 23% had three or more NNRTI mutations. Both adherence measures were significantly associated with VL (P < 0.001). Suboptimal adherence was significantly associated with resistance mutations (P < 0.02). The findings illustrate for the first time the strong association between suboptimal adherence, treatment failure and drug resistance to first-line HAART in India. The predictive value of standard adherence measures was improved by including treatment interruption data. The observed mutations can jeopardise future treatment options, especially in light of limited access to second-line treatments. To develop effective adherence interventions, research is needed to examine culturally-specific reasons for treatment interruptions.

Long-term efficacy of first line antiretroviral therapy in Indian HIV-1 infected patients: a longitudinal cohort study

Background

Short term efficacy of combination antiretroviral therapy (cART) in resource-constrained settings is comparable to that found in western studies. However, long term data are limited. India has the third largest HIV infected population in the world but the long-term outcome of first line therapy according to the national guidelines has not been evaluated yet. Therefore, we conducted a long-term longitudinal analysis of the efficacy of the national first-line therapy in India from an observational cohort of Indian patients in two different clinical settings.

Methodology/Principal Findings

A total 323 patients who had been on ART for a median of 23 months and achieved virological suppression <100 copies/ml by their study baseline visit, were included and followed for two years. Blood samples were collected every six months for viral load and CD4 count. Drug resistance genotyping was performed when the viral load was >2000 copies/mL. Adherence and treatment interruptions (>48 h) were assessed via self-report. In the studied patients, the median duration of viral suppression was 44 months; 15.8% of patients showed viral rebound, and 2.8% viral failure. Viral rebound or failure was significantly negatively related to perfect adherence (100% adherence and no treatment interruption >48 hrs). Virological re-suppression in the subsequent visit was observed in three patients without any change in therapy despite the presence of key mutations.

Conclusion/Significance

Our study reports for the first time, a good long-term response to the first line therapy for a median of nearly four years although a less than perfect adherence increases the risk for treatment failure and subsequent drug resistance development. The empirical findings in this study also indicate the overall success of the Indian ART program in two different settings which likely are representative of other clinics that operate under the national guidelines.

Comparing adherence to two different HIV antiretroviral regimens: an instrumental variable analysis

The objective of this observational cohort study was to compare adherence to protease inhibitor (PI)-based regimens or non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens. HIV-seropositive, antiretroviral-naïve patients initiating therapy between 1998 and 2006 were identified using Veterans Health Administration databases. First-year adherence ratios were calculated as proportion of days covered (PDC). Multivariable regressions were run with an indicator for PDC >95, 90, 85, and 80 % as the dependent variable and an indicator for a PI-based regimen as the key independent variable. We controlled for residual unmeasured confounding by indication using an instrumental variable technique, using the physician's prescribing preference as the instrument. Out of 929 veterans on PI-based and 747 on NNRTI-based regimens, only 19.7 % of PI patients had PDC >80 %, compared to 35.1 % of NNRTI patients. In multivariable analysis, starting a PI regimen was significantly associated with poor adherence for all 4 adherence thresholds using conventional regressions and instrumental variable methods.

Unboosted atazanavir for treatment of HIV infection: rationale and recommendations for use

Atazanavir (Reyataz®) is a protease inhibitor (PI) for the treatment of HIV infection. Several trials have demonstrated the good efficacy and toxicity profile of atazanavir boosted by ritonavir (atazanavir/r). However, several toxicity events and pharmacokinetic issues due to drug-to-drug interactions (partly related to ritonavir) may complicate atazanavir/r therapy. This is why regimens with unboosted atazanavir have been experimented with and are used in clinical practice. The aim of this article is to identify the clinical settings in which unboosted atazanavir may be a safe and effective option for the long-term control of HIV replication. Despite the fact that a favourable lipid profile and good gastrointestinal tolerability have been reported in comparative trials, unboosted atazanavir should not be considered an optimal choice for treatment-naive patients. In fact, boosting with ritonavir produces higher atazanavir plasma levels, which are beneficial in terms of efficacy, especially in untreated patients with high plasma HIV RNA. Clinical data indicate that, in patients with sustained undetectable HIV RNA and without previous virological failure or HIV drug resistance-associated mutations, a switch to unboosted atazanavir-based regimens is a feasible option to control and prevent toxicity events, especially in patients who cannot tolerate ritonavir and in those with severe hyperbilirubinaemia on atazanavir/r. Moreover, while unboosted atazanavir must not be used in pregnant women, it is a recommended option in special populations, such as patients with moderate liver insufficiency. Lastly, unboosted atazanavir in combination with raltegravir may allow the construction of a well tolerated and effective regimen without nucleoside reverse transcriptase inhibitors in patients for whom these drugs are contraindicated. In conclusion, there is a good rationale, significant clinical interest and accumulating clinical experience with unboosted atazanavir-based regimens, although this formulation should be used only in specific situations and as a maintenance strategy. Moreover, therapeutic drug monitoring could be useful in specific circumstances (such as in patients with liver impairment or in case of potential drug-drug interactions).

Effect of adherence as measured by MEMS, ritonavir boosting, and CYP3A5 genotype on atazanavir pharmacokinetics in treatment-naive HIV-infected patients

We investigated population pharmacokinetics and pharmacogenetics of ritonavir-boosted atazanavir (ATV), using drug intake times exactly recorded by the Medication Event Monitoring System. The ANRS 134-COPHAR 3 trial was conducted in 35 HIV-infected treatment-naive patients. ATV (300 mg), ritonavir (100 mg), and tenofovir (300 mg) + emtricitabine (200 mg), in bottles with MEMS caps, were taken once daily for 6 months. Six blood samples were collected at week 4 to measure drug concentrations, and trough levels were measured bimonthly. A model integrating ATV and ritonavir pharmacokinetics and pharmacogenetics used nonlinear mixed effects. Use of exact dosing data halved unexplained variability in ATV clearance. The ritonavir-ATV interaction model suggested that optimal boosting effect is achievable at lower ritonavir exposures. Patients with at least one copy of the CYP3A5*1 allele exhibited 28% higher oral clearance. We provide evidence that variability in ATV pharmacokinetics is defined by adherence, CYP3A5 genotype, and ritonavir exposure.

Design and characterization of novel peptide-coated lipid nanoparticles for targeting anti-HIV drug to CD4 expressing cells

Human immunodeficiency virus (HIV) persists in lymph nodes and lymphoid tissues even during aggressive drug treatment, likely due to insufficient drug concentrations at this site. Therefore, to eliminate this residual virus, methods that enhance lymph node drug concentrations are currently being evaluated. Although enhanced drug concentrations in tissue have been achieved with drug-associated lipid nanoparticles, targeting these particles to CD4(+) cells may provide specific delivery of drug to HIV target cells and further enhance drug efficacy. We have evaluated four candidate peptides with reported binding specificity to CD4 for anchoring on lipid nanoparticle preparations previously shown to localize in lymph nodes. Terminal cysteine containing candidate peptides were conjugated to lipid nanoparticles through maleimide-linked phospholipids for targeting to CD4 cells. Using fluorescently labeled lipid nanoparticle binding to cells with varying degree of CD4 expression (CEMx174, Molt-4, Jurkat, and Ramos), we indentified two peptide sequences that provided CD4 selectivity to nanoparticles. These two peptide candidates on lipid nanoparticles bound to cells corresponding to the degree of CD4 expression and in a peptide dose dependent manner. Further, binding of these targeted lipid nanoparticles was CD4 specific, as pre-exposure of CD4(+) cells to anti-CD4 antibodies or free peptides inhibited the binding interactions. These results indicate targeting of lipid nanoparticles for specific binding to CD4 can be accomplished by tagging CD4 binding peptides with peptides, and these results provide a basis for further evaluation of this targeted delivery system to enhance antiviral drug delivery to CD4(+) HIV host cells, particularly those in lymph nodes and lymphoid tissues.

CD4+ T-cell counts and plasma HIV-1 RNA levels beyond 5 years of highly active antiretroviral therapy

BACKGROUND

The heterogeneity of CD4 T-cell counts and HIV-1 RNA at 5-12 years after the initiation of highly active antiretroviral therapy (HAART) remains largely uncharacterized.

METHODS

In the Multicenter AIDS Cohort Study, 614 men who initiated HAART contributed data 5-12 years subsequently. Multivariate regression was used to evaluate the predictors of CD4 counts and HIV-1 RNA levels.

RESULTS

At 5 to 12 years post-HAART, the median CD4 T-cell count was 586 (interquartile range, 421-791) cells per microliter and 78% of the HIV-1 RNA measurements were undetectable. Higher CD4 T-cell counts 5-12 years post HAART were predicted by higher CD4 T-cell counts and higher total lymphocyte count pre HAART, lack of hepatitis B or C virus coinfections, and greater CD4 T-cell change and suppressed HIV-1 RNA in the first 5 years after starting HAART. Men who were 50 years and older with 351-500 CD4 cells per microliter at HAART initiation had adjusted mean CD4 T-cell count of 643 cells per microliter at 10-12 years post HAART, which was similar to the adjusted mean CD4 T-cell count (670 cells/μL, P = 0.45) in this period for younger men starting HAART with lower CD4 T-cell counts. HIV-1 RNA suppression in the first 5 years post HAART predicted subsequent viral suppression.

CONCLUSIONS

Immunological and virological responses in the first 5 years post HAART predicted subsequent CD4 T-cell counts and HIV-1 RNA levels. The association between age and subsequent CD4 T-cell count supports incorporating age in the guidelines for use of HAART.

Work-related barriers and facilitators to antiretroviral therapy adherence in persons living with HIV infection

Little is known about how the structure of work affects adherence to HIV antiretroviral therapy. We surveyed participants in an adherence intervention study to learn more about job characteristics, including measures of psychological demand and control, and job accommodations. Adherence was assessed using the Medication Event Monitoring System. Of 156 trial subjects, 69 were employed, and these 69 made 229 study visits. Psychological demands and control were unrelated to adherence, but the presence of workplace accommodations was significantly associated with adherence (P < 0.05). In multivariable models adjusting for clustering, those who reported having received an accommodation were 12% more adherent than those who did not receive an accommodation. Adherence was unrelated to experiencing side effects affecting work performance. Having the ability to institute job accommodations was more important to adherence than the psychosocial structure of the work. These potential benefits of requesting modifications need to be weighed against the possible risks of workplace disclosure.

Assessing the viorologic and adherence benefits of patient-selected HIV treatment partners in a resource-limited setting

OBJECTIVE

To determine the efficacy of patient-selected treatment partners on virologic and adherence outcomes during first-line antiretroviral therapy.

DESIGN

Randomized controlled trial. SETTING AND ANALYTICAL APPROACH: Between June 2006 and December 2007, 499 HIV-infected adults in Jos, Nigeria, were randomized to standard of care (SOC) or patient-selected treatment partner-assisted therapy (TPA). Each patient was followed for 48 weeks. Virologic outcomes, adherence to drug pick-up, CD4 cell counts, and mortality are reported.

RESULTS

At week 24, undetectable viral load was achieved by 61.7% of patients in the TPA arm versus 50.2% of those receiving SOC [odds ratio (OR) = 1.58, 95% CI: 1.11 to 2.26, P < 0.05]. There was no significant difference at week 48: 65.3% versus 59.4% for TPA and SOC, respectively (OR = 1.28, 95% CI: 0.89 to 1.84, P > 0.05). The TPA group had more than 3 times the odds of at least 95% drug pickup adherence through week 24 (OR = 3.06, 95% CI: 1.89 to 4.94, P < 0.01) and almost twice the odds through week 48 (OR = 1.95, 95% CI: 1.29 to 2.93, P < 0.01). At week 48, there were no significant differences in CD4 cell count increases (t = -0.09, df = 404, P > 0.05) or mortality (10.6% vs. 6.1%) between TPA vs. SOC, respectively. Residence-to-clinic distance was significantly associated with virologic and adherence outcomes.

CONCLUSIONS

Use of patient-selected treatment partners was associated with improved drug pickup adherence and initial virologic success but had no durable effect on attaining undetectable viral load.

P-glycoprotein mediates efflux transport of darunavir in human intestinal Caco-2 and ABCB1 gene-transfected renal LLC-PK1 cell lines

Darunavir (DRV) is a nonpeptidic protease inhibitor (PI) approved for the treatment of human immunodeficiency virus (HIV) infection. DRV displays potent activity against HIV strains resistant to other available PIs. Coadministration with ritonavir (RTV) improves the oral bioavailability of DRV. Inhibition of cytochrome P450 by RTV has been proposed as a mechanism for enhanced DRV bioavailability. However, interaction of these drugs with intestinal transporters has not been elucidated. This study was performed to explore the involvement of P-glycoprotein in transcellular DRV transport in monolayers of human intestinal Caco-2 and in ABCB1 multidrug resistance 1, (MDR1) gene-transfected renal LLC-PK1 (L-MDR1) cell lines. Transepithelial transport of DRV in Caco-2 cell monolayers was 2-fold greater in the basal-to-apical direction compared to that in the opposite direction. RTV had a significant inhibitory effect on the efflux transport of DRV in Caco-2 cells. The apical-to-basal DRV transport was enhanced by P-glycoprotein inhibitors, cyclosporin A and verapamil, as well as multidrug resistance-related protein (MRP/ABCC) inhibitors, probenecid and MK571. Using the L-MDR1 cell line, basal-to-apical DRV transport was much greater than in the opposite direction. Furthermore, cyclosporin A markedly inhibited the basal-to-apical DRV transport. RTV significantly increased the apical-to-basal transport of DRV in L-MDR1 cells, but reduced transport in the opposite direction. DRV inhibited P-glycoprotein-mediated efflux of calcein-acetoxymethyl ester in L-MDR1 cells with the inhibitory potency of 121 microM. These findings suggest that DRV is a substrate of P-glycoprotein and MRP, most likely MRP2. RTV appeared to inhibit P-glycoprotein, thereby enhancing the absorptive transport of DRV.

Randomization to once-daily stavudine extended release/lamivudine/efavirenz versus a more frequent regimen improves adherence while maintaining viral suppression

BACKGROUND

In antiretroviral (ARV) therapy, pill burden, dosing frequency, and regimen complexity adversely affect adherence. We sought to evaluate the effect of regimen simplification on maintenance of virologic suppression and treatment adherence.

METHOD

In this 48-week, open-label, randomized study, 320 HIV-1-infected adult patients with a viral load of <50 copies/mL on a twice-daily or more frequent ARV regimen were either switched to a once-daily regimen of efavirenz, extended-release stavudine, and lamivudine (QD arm) or continued on existing therapy (BID+ arm). Medication Event Monitoring System (MEMS) caps, AIDS Clinical Trials Group (ACTG)-validated questionnaire, and pill counts were used to evaluate adherence. Treatment satisfaction and preference were also evaluated.

RESULTS

The QD arm was noninferior to the BID+ arm in the primary efficacy measure (proportion of patients who maintained virologic suppression at Week 48; QD arm, 80.0% vs. BID+ arm, 75.8%). Adherence and treatment satisfaction significantly favored the QD arm, in which 91.0% of patients preferred the simpler regimen. Overall, the majority of adverse events were mild to moderate in severity and resulted in a low rate of treatment discontinuations.

CONCLUSIONS

Simplifying twice-daily or more frequent ARV therapy to a once-daily efavirenz-containing regimen in virologically suppressed HIV-1-infected patients maintains virologic suppression while improving adherence and patient satisfaction.

Time Trends for HIV-1 Antiretroviral Resistance Among Antiretroviral-Experienced and Naive Pregnant Women in New York City During 1991 to Early 2001

Time trends in the prevalence of drug resistance to antiretroviral therapy (ART) in pregnant women have not been studied. Treatment and prophylactic efficacy could be compromised by drug-resistant HIV strains. We conducted a repeated cross-sectional study of antiretroviral resistance mutations to nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs) and of major mutations to protease inhibitors (PIs) in virus isolates from 300 HIV-infected pregnant women in New York City from 1991 to early 2001. The overall prevalence of mutations for NRTIs from 1991 to early 2001 was higher for ART-experienced (25.6% [95% confidence interval (CI): 19.1% to 32.1%]) than ART-naive (8.6% [95% CI: 3.7% to 13.4%]) mothers (P < 0.002). For NNRTIs, the overall prevalence of mutations was somewhat higher among ART-experienced (5.8% [95% CI: 2.3% to 9.3%]) versus ART-naive (1.6% [95% CI: 0% to 3.7%]) women (P = 0.06), and increased over time for ART-naive women (0%-7.4%; P = 0.03) and ART-experienced women (0%-19.4%; P = 0.0002). The prevalence of PI-associated mutations was also higher overall among ART-experienced mothers (5.8% [95% CI: 2.3% to 9.3%] vs. 1.6% [95% CI: 0% to 3.7%]; P = 0.06), with increases over time seen for ART-naive women (0%-7.4%; P = 0.03) and ART-experienced women (0%-16.1%; P = 0.0008). The increasing prevalence of drug resistance in pregnant women, including those who are drug-naive, underscores the necessity for resistance testing to guide treatment to achieve suppression of the mother's virus.

Conservation of First-Line Antiretroviral Treatment Regimen where Therapeutic Options are Limited

Objectives

To determine rates and causes of switching from first- to second-line antiretroviral treatment (ART) regimens in a large treatment-naive cohort (a South African community-based ART service) where a targeted adherence intervention was used to manage initial virological breakthrough.

Methods

ART-naive adults ( n=929) commencing first-line non-nucleoside-based ART [according to WHO (2002) guidelines] between September 2002 and August 2005 were studied prospectively. Viral load (VL) and CD4+ T-cell counts were monitored every 4 months. All drug switches were recorded. Counsellor-driven adherence interventions were targeted to patients with a VL >1,000 copies/ml at any visit (virological breakthrough) and the VL measurement was repeated within 8 weeks. Two consecutive VL measurements >1,000 copies/ml was considered virological failure, triggering change to a second-line regimen.

Results

During 760 person-years of observation [median IQR) 189 (85–441) days], 823 (89%) patients were retained on ART, 2% transferred elsewhere, 7% died and 3% were lost to follow-up. A total of 893 (96%) patients remained on first-line therapy and 16 (1.7%) switched to second-line due to hypersensitivity reactions ( n=9) or lactic acidosis ( n=7). A Kaplan-Meier estimate for switching to second-line due to toxicity was 3.0% at 32 months. Virological breakthrough occurred in 67 (7.2%) patients, but, following use of a targeted adherence intervention, virological failure was confirmed in just 20 (2.2%). Kaplan-Meier estimates at 32 months were 20% for virological breakthrough but only 5.6% for confirmed virological failure.

Conclusion

Regimen switches were due to virological failure or toxicity. Although follow-up time was limited, over 95% of individuals remained on first-line ART using a combination of viral monitoring and a targeted adherence intervention.

Explaining variability in the relationship between antiretroviral adherence and HIV mutation accumulation

OBJECTIVES

Determining the relationship between antiretroviral adherence and resistance accumulation is important for the design and evaluation of adherence interventions. Our objective was to explain heterogeneity observed in this relationship.

METHODS

We first conducted a systematic review to locate published reports describing the relationship between adherence and resistance. We then used a validated computer simulation to simulate the patient populations in these reports, exploring the impact of changes in individual patient characteristics (age, CD4, viral load, prior antiretroviral experience) on the shape of the adherence-resistance (A-R) curve.

RESULTS

The search identified 493 titles, of which 3 contained relevant primary data and 2 had sufficient follow-up for inclusion (HOMER and REACH cohorts). When simulating HOMER, the A-R curve had a high peak with a greatly increased hazard ratio (HR) of accumulating mutations at partial compared to complete adherence (simulation, HR 2.9; HOMER, HR 2.7). When simulating REACH, the A-R curve had a shallow peak with a slightly increased hazard of accumulating mutations at partial adherence (simulation, HR 1.2; REACH, HR 1.4). This heterogeneity was primarily attributable to differences in antiretroviral experience between the cohorts.

CONCLUSIONS

Our computer simulation was able to explain much of the heterogeneity in observed A-R curves.

'Simply forgot' is the most frequently stated reason for missed doses of HAART irrespective of degree of adherence

OBJECTIVES

Previous studies have reported that forgetfulness is the most frequently mentioned reason for missed doses among patients on highly active antiretroviral therapy (HAART). However, no previous study has compared the reasons given by highly nonadherent patients with the reasons given by patients with better adherence. The objective of this study was to examine further patients' self-reported reasons for missing doses of HAART and to compare the reasons given by patients with lower adherence with those given by patients with higher adherence.

METHODS

All patients visiting the clinics participating in the Danish HIV cohort study during a 1-year period (July 2002 to June 2003) were eligible if they had started HAART at least 6 months previously. Consenting patients completed an anonymous self-administered questionnaire based upon the adult AIDS Clinical Trial Group adherence questionnaires. Lower adherence was defined as reporting a missed dose within the preceding 4 days.

RESULTS

We received usable questionnaires from 840 (75%) of the 1126 eligible patients. Patients with lower adherence reported the same reasons for missed doses as patients with higher adherence (Spearman's rho=0.952, P<0.0001). In both groups of patients the three most frequently reported reasons for missed doses were 'simply forgot', 'were away from home', and 'had a change in daily routines'.

CONCLUSIONS

Patients with poorer adherence to HAART state the same reasons for missing doses as patients with better adherence, and 'simply forgot' is the most frequently stated reason.

Declining Prevalence of HIV-Infected Individuals at Risk of Transmitting Drug-Resistant HIV in Denmark during 1997–2004

Background

Transmission of drug-resistant HIV is a potential threat to the substantial clinical benefit of highly active antiretroviral therapy (HAART). To explore the background for the low rates of drug resistance transmission (2–5%) in our population, we estimated acquisition of HIV drug resistance and examined temporal trends in the prevalence of patients at risk of transmitting drug-resistant HIV.

Methods

The study population included all 4,025 patients from The Danish HIV Cohort Study seen during the period 1995–2004. Virological failure to a given drug class was defined as a viral load (VL) >1,000 copies/ml for 120 days while on a HAART regimen including that drug class. In addition, receiving nucleoside reverse transcriptase inhibitors (NRTIs) for 180 days before HAART counted as NRTI failure irrespective of VL. Having experienced failure was considered a proxy for harbouring drug-resistant virus in subsequent observation time. Patients with a current VL >1,000 copies/ml were considered at risk of transmitting HIV.

Results

We found a decrease from 1997 to 2004 in the prevalence of potential transmitters of drug-resistant HIV. The number of these patients with previous NRTI failure decreased from 429 (24% of all patients) in 1998 to 213 (8.0% of all patients) in 2004. Previous protease inhibitor (PI) failure peaked at 279 (14%) in 1999, declining to 142 (5.3%) in 2004. Previous NNRTI failure peaked at 121 patients (4.7%) in 2002, and occurred in 113 patients (4.2%) in 2004. Of all 686 potential transmitters in 2004, 31% had previously experienced NRTI failure, 21% PI failure, and 16% non-NRTI failure.

Conclusion

In the population of HIV-infected individuals in Denmark with complete follow-up, the number at risk of transmitting drug-resistant virus declined over time.

Predictors of virologic failure in HIV-1-infected patients starting highly active antiretroviral therapy in Porto Alegre, Brazil

OBJECTIVE

To assess predictors of virologic response 6 months after initiation of highly active antiretroviral therapy (HAART) in a cohort of HIV-infected patients in Brazil.

METHODS

Treatment-naive patients who started HAART between 1996 and 2004 and had information on viral load at 3-9 months were included. Information was collected on demographic characteristics, antiretroviral regimen, adherence, AIDS diagnosis, baseline CD4 cell count, and viral load. Virologic failure (VF) was defined as viral load > or =400 copies/mL at 6 months or death before completion of 6 months of therapy.

RESULTS

Among 454 patients who met the inclusion criteria, VF occurred in 127 (28.0%). In univariate analysis, VF was associated with younger age (median 34 vs. 37 years, P = 0.003), AIDS diagnosis (relative risk [RR] 1.18, P = 0.009), higher baseline viral load (5.34 vs. 5.00, P = 0.0002), lower baseline CD4 cell count (86 vs. 182, P = 0.006), nonadherence (RR 1.39, P < 0.0001), regimen containing 1 single protease inhibitor, as compared with ritonavir-boosted regimens (odds ratio [OR] 8.5, P < 0.0001), and year therapy initiated before 1999 (P < 0.0001). To minimize the systematic effect of therapy indication, we analyzed the subset of 158 patients with CD4 count < or =200 cells/microL who started therapy after 1999. After adjusting for age, education, adherence, regimen, and baseline viral load, nonadherence (OR 8.78, P = 0.02), and fewer years of education (OR 6.05, P = 0.05) remained associated with VF.

CONCLUSIONS

A significant improvement was found in virologic suppression over time, consistent with the introduction of nonnucleoside reverse transcriptase inhibitors and ritonavir-boosted regimens into clinical practice. With currently available therapies, compliance and education were shown to be predictors of virologic response, particularly in more immunocompromised patients.

Declining risk of triple-class antiretroviral drug failure in Danish HIV-infected individuals

OBJECTIVES

To analyse the incidence, prevalence, and predictors for development of triple-class antiretroviral drug failure (TCF) in individuals infected with HIV.

DESIGN

Population-based observational cohort study from 1 January 1995 to 31 December 2003, focusing on all 2722 recipients of highly active antiretroviral therapy (HAART) in Denmark.

METHODS

We used person-years analysis, Kaplan-Meier survival curves and Cox regression analysis. TCF was defined as a minimum of 120 days with viral load > 1000 copies/ml on treatment with each of the three major drug classes.

RESULTS

We observed 177 TCFs, yielding a crude incidence rate (IR) of 1.8 per 100 person-years [95% confidence interval (CI), 1.6-2.1]. Seven years after initiation of HAART, 17.2% (95% CI, 14.5-20.5) of antiretroviral (ART)-experienced patients, but only 7.0% (95% CI, 4.3-11.2) of ART-naive patients were estimated to have failed. After an initial rise, the IR from the third to the sixth year of HAART declined significantly for ART-experienced patients [incidence rate ratio (IRR), 0.80 per year (95% CI, 0.66-0.97); P = 0.022], and non-significantly for ART-naive patients [IRR, 0.79 per year (95% CI, 0.53-1.18); P = 0.255]. The IR for all patients being followed each year declined from 1997 to 2003 [IRR, 0.88 (95% CI, 0.81-0.96); P = 0.002]. The prevalence of TCF remained stable at less than 7% after 2000. Predictors of TCF at commencement of HAART were a CD4 cell count below 200, a previous AIDS-defining event, previous antiretroviral exposure, earlier year of HAART initiation, and young age.

CONCLUSIONS

The risk of TCF is declining in Denmark and the prevalence remains stable.