Virological rebound after suppression on highly active antiretroviral therapy

Latent Class Analysis of Syndemic Factors Associated with Sustained Viral Suppression among Ryan White HIV/AIDS Program Clients in Miami, 2017

The study's objective was to identify the association between sustained viral suppression (all viral load tests < 200 copies/ml per year) and patterns of co-occurring risk factors including, mental health, substance use, sexual risk behavior, and adverse social conditions for people with HIV (PWH). Latent class analysis followed by multivariable logistic regression was conducted for 6554 PWH in the Miami-Dade County Ryan White Program during 2017, and a five-class model was selected. Compared to Class 1 (no risk factors), the odds of achieving sustained viral suppression was significantly lower for Class 2 (mental health) (aOR: 0.67; 95% CI 0.54-0.83), Class 3 (substance use and multiple sexual partners) (0.60; 0.47-0.76), Class 4 (substance use, multiple sexual partners, and domestic violence) (0.71; 0.55-0.93), and Class 5 (mental health, substance use, multiple sexual partners, domestic violence, and homelessness) (0.26; 0.19-0.35). Findings indicate the need for targeted interventions that address these syndemic factors.

Virologic response of adolescents living with perinatally acquired HIV receiving antiretroviral therapy in the period of early adolescence (10-14 years) in South Africa

BACKGROUND AND OBJECTIVES

Adolescents living with perinatally acquired HIV (ALPHIV) on antiretroviral therapy (ART) have been noted to have poorer adherence, retention and virologic control compared to adolescents with non-perinatally acquired HIV, children or adults. We aimed to describe and examine factors associated with longitudinal virologic response during early adolescence.

DESIGN

A retrospective cohort study.

METHODS

We included ALPHIV who initiated ART before age 9.5 years in South African cohorts of the International epidemiology Database to Evaluate AIDS-Southern Africa (IeDEA-SA) collaboration (2004-2016); with viral load (VL) values <400 copies/ml at age 10 years and at least one VL measurement after age 10 years. We used a log-linear quantile mixed model to assess factors associated with elevated (75th quantile) VLs.

RESULTS

We included 4396 ALPHIV, 50.7% were male, with median (interquartile range) age at ART start of 6.5 (4.5, 8.1) years. Of these, 74.9% were on a non-nucleoside reverse transcriptase inhibitor (NNRTI) at age 10 years. After adjusting for other patient characteristics, the 75th quantile VLs increased with increasing age being 3.13-fold (95% CI 2.66, 3.68) higher at age 14 versus age 10, were 3.25-fold (95% CI 2.81, 3.75) higher for patients on second-line protease-inhibitor and 1.81-fold for second-line NNRTI-based regimens (versus first-line NNRTI-based regimens). There was no difference by sex.

CONCLUSIONS

As adolescents age between 10 and 14 years, they are increasingly likely to experience higher VL values, particularly if receiving second-line protease inhibitor or NNRTI-based regimens, which warrant adherence support interventions.

Evaluating HIV Viral Rebound Among Persons on Suppressive Antiretroviral Treatment in the Era of "Undetectable Equals Untransmittable (U = U)"

Background

Studies have demonstrated that persons with HIV (PWH) maintaining viral suppression do not transmit HIV to HIV-negative partners through condomless sex, leading to the “Undetectable = Untransmittable (U = U)” prevention campaign. However, few studies have examined the durability of suppression in the era of U = U.

Methods

This retrospective cohort study was conducted in Providence, Rhode Island. PWH aged ≥18 years with documented viral suppression (defined as at least 1 viral load [VL] <200 copies/mL and no VL ≥200 copies/mL) in 2015 were included in the baseline cohort. Primary outcomes were viral suppression, viral rebound (at least 1 VL ≥200 copies/mL), or gap in VL monitoring assessed annually from 2016 to 2019. Those with viral rebound were assessed for resuppression within 6 months. Demographic and clinical characteristics associated with viral rebound or gaps in VL monitoring were investigated by bivariate analysis and logistic regression.

Results

A total of 1242 patients with viral suppression were included in the baseline cohort. In each follow-up year, 85%–90% maintained viral suppression, 2%–5% experienced viral rebound, and 8%–10% had a gap in VL monitoring. Among those with viral rebound, approximately one-half were suppressed again within 6 months. In the logistic regression models, retention in care was significantly associated with viral suppression, while younger age, black race, high school or equivalent education, non–men who have sex with men, and history of incarceration were significantly associated with viral rebound.

Conclusions

In the U = U era, most patients with viral suppression who are retained in care are likely to maintain viral suppression over time. Some patients require additional support for regular VL monitoring.

The Pharmacogenetics of Efavirenz Metabolism in Children: The Potential Genetic and Medical Contributions to Child Development in the Context of Long-Term ARV Treatment

Efavirenz (EFV) is a well-known, effective anti-retroviral drug long used in first-line treatment for children and adults with HIV and HIV/AIDS. Due to its narrow window of effective concentrations, between 1 and 4 μg/mL, and neurological side effects at supratherapeutic levels, several investigations into the pharmacokinetics of the drug and its genetic underpinnings have been carried out, primarily with adult samples. A number of studies, however, have examined the genetic influences on the metabolism of EFV in children. Their primary goal has been to shed light on issues of appropriate pediatric dosing, as well as the manifestation of neurotoxic effects of EFV in some children. Although EFV is currently being phased out of use for the treatment of both adults and children, we share this line of research to highlight an important aspect of medical treatment that is relevant to understanding the development of children diagnosed with HIV.

Promising Approaches for Engaging Youth and Young Adults Living with HIV in HIV Primary Care Using Social Media and Mobile Technology Interventions: Protocol for the SPNS Social Media Initiative

Background

In the United States, disparities in the rates of HIV care among youth and young adults result from the intersections of factors that include stigma, substance use, homelessness or marginal housing, institutional neglect, and mental health issues. Novel interventions are needed that are geared to youth and young adults.

Objective

In this paper, we aim to describe the interventions used by participating sites for Using Social Media initiative, the process for classifying the intervention components, and the methods for conducting a comprehensive evaluation of the interventions.

Methods

In 2015, the Health Resources and Services Administration (HRSA) HIV/AIDS Bureau, Special Projects of National Significance (SPNS) funded the Evaluation and Technical Assistance Center (ETAC) at the University of California, Los Angeles and 10 demonstration projects at sites across the United States that incorporated innovative approaches using a variety of social media and mobile technology strategies designed specifically for youth and young adults living with HIV. The ETAC developed a typology, or a classification system, that systematically summarizes the principal components of the interventions into broader groups and developed a multisite, mixed-methods approach to evaluate them based on the Department of Health and Human Services HIV health outcomes along the HIV care continuum. The mixed-methods approach is key to remove potential biases in assessing the effectiveness of demonstration projects.

Results

This SPNS project was funded in September 2015, and enrollment was completed on May 31, 2018. A total of 984 participants have been enrolled in the multisite evaluation. Data collection will continue until August 2019. However, data analysis is currently underway, and the first results are expected to be submitted for publication in 2019.

Conclusions

This HRSA-funded initiative seeks to increase engagement in HIV medical care, improve health outcomes for people living with HIV, and reduce HIV-related health disparities and health inequities that affect HIV-positive youth and young adults.

International Registered Report Identifier (IRRID)

DERR1-10.2196/10681

Substance Use, Demographic and Socioeconomic Factors Are Independently Associated With Postpartum HIV Care Engagement in the Southern United States, 1999-2016

Background

Retention in care (RIC) and viral suppression (VS) are associated with reduced HIV transmission and mortality. Studies addressing postpartum engagement in HIV care have been limited by small sample size, short follow-up, and a lack of data from the Southeast United States.

Methods

HIV-positive adult women with ≥1 prenatal visit at the Vanderbilt Obstetrics Comprehensive Care Clinic from 1999 to 2015 were included. Poor RIC was defined as not having ≥2 encounters per year, ≥90 days apart; poor VS was a viral load >200 copies/mL. Modified Poisson regression was used to estimate adjusted relative risks (aRRs) of poor postpartum RIC and VS.

Results

Among 248 women over 2070 person-years of follow-up, 37.6% person-years had poor RIC and 50.4% lacked VS. Prenatal substance use was independently associated with poor RIC (aRR, 1.40; 95% confidence interval [CI], 1.08–1.80) and poor VS (aRR, 1.20; 95% CI, 1.04–1.38), and lack of VS at enrollment was associated with poor RIC (aRR, 1.64; 95% CI, 1.15–2.35) and poor VS (aRR, 1.59; 95% CI, 1.30–1.94). Hispanic women were less likely and women with lower educational attainment were more likely to have poor RIC. Women >30 years of age and married women were less likely to have poor VS.

Conclusions

In this population of women in prenatal care at an HIV primary medical home in Tennessee, women with prenatal substance use and a lack of VS at enrollment into prenatal care were at greater risk of poor RIC and lack of VS postpartum. Interventions aimed at improving postpartum engagement in HIV care among these high-risk groups are needed.

Incidence of Postsuppression Virologic Rebound in Perinatally HIV-Infected Asian Adolescents on Stable Combination Antiretroviral Therapy

PURPOSE

To assess the incidence and predictors of postsuppression virologic rebound (VR) among adolescents on stable combination antiretroviral therapy in Asia.

METHODS

Perinatally HIV-infected Asian adolescents (10-19 years) with documented virologic suppression (two consecutive viral loads [VLs] <400 copies/mL ≥6 months apart) were included. Baseline was the date of the first VL <400 copies/mL at age ≥10 years or the 10th birthday for those with prior suppression. Cox proportional hazards models were used to identify predictors of postsuppression VR (VL >1,000 copies/mL).

RESULTS

Of 1,379 eligible adolescents, 47% were males. At baseline, 22% were receiving protease inhibitor-containing regimens; median CD4 cell count (interquartile range [IQR]) was 685 (448-937) cells/mm³; 2% had preadolescent virologic failure (VF) before subsequent suppression. During adolescence, 180 individuals (13%) experienced postsuppression VR at a rate of 3.4 (95% confidence interval: 2.9-3.9) per 100 person-years, which was consistent over time. Median time to VR during adolescence (IQR) was 3.3 (2.1-4.8) years. Wasting (weight-for-age z-score <-2.5), being raised by grandparents, receiving second-line protease inhibitor-based regimens, starting combination antiretroviral therapy after 2005, and having preadolescent VF were independent predictors of adolescent VR. At VR, median age, CD4 cell count, and VL (IQR) were 14.8 (13.2-16.4) years, 507 (325-723) cells/mm³, and 4.1 (3.5-4.7) log₁₀ copies/mL, respectively.

CONCLUSIONS

A modest and consistent incidence of postsuppression VR was documented during adolescence in our cohort. Having poor weight, receiving second-line regimens, and prior VF were associated with an increased VR rate. Adolescents at higher risk of VR may benefit from more intensive VL monitoring to enhance adherence management.

Durability of viral suppression with first-line antiretroviral therapy in patients with HIV in the UK: an observational cohort study

BACKGROUND

The length of time that people with HIV on antiretroviral therapy (ART) with viral load suppression will be able to continue before developing viral rebound is unknown. We aimed to investigate the rate of first viral rebound in people that have achieved initial suppression with ART, to determine factors associated with viral rebound, and to use these estimates to predict long-term durability of viral suppression.

METHODS

The UK Collaborative HIV Cohort (UK CHIC) Study is an ongoing multicentre cohort study that brings together in a standardised format data on people with HIV attending clinics around the UK. We included participants who started ART with three or more drugs and who had achieved viral suppression (≤50 copies per mL) by 9 months after the start of ART (baseline). Viral rebound was defined as the first single viral load of more than 200 copies per mL or treatment interruption (for ≥1 month). We investigated factors associated with viral rebound with Poisson regression. These results were used to calculate the rate of viral rebound according to several key factors, including age, calendar year at start of ART, and time since baseline.

RESULTS

Of the 16 101 people included, 4519 had a first viral rebound over 58 038 person-years (7·8 per 100 person-years, 95% CI 7·6-8·0). Of the 4519 viral rebounds, 3105 (69%) were defined by measurement of a single viral load of more than 200 copies per mL, and 1414 (31%) by a documented treatment interruption. The rate of first viral rebound declined substantially over time until 7 years from baseline. The other factors associated with viral rebound were current age at follow-up and calendar year at ART initiation (p<0·0001) and HIV risk group (p<0·0001); higher pre-ART CD4 count (p=0·0008) and pre-ART viral load (p=0·0003) were associated with viral rebound in the multivariate analysis only. For 1322 (29%) of the 3105 people with observed viral rebound, the next viral load value after rebound was 50 copies per mL or less with no regimen change. For HIV-positive men who have sex with men, our estimates suggest that the probability of first viral rebound reaches a plateau of 1·4% per year after 45 years of age, and 1·0% when accounting for the fact that 29% of viral rebounds are temporary elevations.

INTERPRETATION

A substantial proportion of people on ART will not have viral rebound over their lifetime, which has implications for people with HIV and the planning of future drug development.

FUNDING

UK Medical Research Council.

Retention in Continuous Care and Sustained Viral Suppression

OBJECTIVES

To examine the relationship between retention in continuous care and sustained viral suppression.

METHODS

The authors retrospectively followed 653 persons who were virally suppressed and seeking care at an infectious disease clinic in Kentucky for an average of 6 years to determine the rates of retention in medical care (≥2 visits separated by ≥3 months within a 12-month period) and sustained viral suppression (<400 copies/mL). A generalized linear mixed model was used to determine an association between retention and suppression over time.

RESULTS

Approximately 61% of the study population were retained in continuous care and 75% had sustained viral suppression for all patient-years. Persons retained in care were 3 times the odds of sustaining viral suppression over time ( P < .001).

CONCLUSION

Retention is essential to achieving and maintaining viral suppression. Strategies should be set in place that emphasize increasing the rates of retention, which in turn may increase the rates of suppression.

Development of real-time PCR for quantitation of simian immunodeficiency virus 2-LTR circles

BACKGROUND

Non-human primates infected with simian immunodeficiency virus (SIV) represent a robust model to evaluate pre-clinical efficacy of HIV-1 preventive strategies and to determine the size of reservoir.

METHODS

We developed a real-time qPCR assay to specifically quantify episomal 2-LTR circular DNA in peripheral blood mononuclear cells and brain tissues from SIV-infected macaques.

RESULTS

This assay has sensitivity, accuracy and reproducibility over seven orders of magnitude. High copy numbers of SIV 2-LTR circles were correlated to high proviral DNA levels in brains of two SIV encephalitic animals. In contrast, no 2-LTR circles were detectable in two SIV-infected animals with no sign of encephalitis or two animals that had mild encephalitis with low levels of proviral DNA.

CONCLUSIONS

These results suggest that simultaneous application of total proviral DNA and 2-LTR circle assays provides quantitative evaluation of pathogenesis and outcome of SIV infection in macaques.

Elevated CD8 T-cell counts and virological failure in HIV-infected patients after combination antiretroviral therapy

Elevated CD8 counts with combination antiretroviral therapy (cART) initiation may be an early warning indicator for future treatment failure. Thus, we investigated whether elevated CD8 counts were associated with virological failure (VF) in the first 4 years of cART in Asian HIV-infected patients in a multicenter regional cohort.We included patients from the TREAT Asia HIV Observational Database (TAHOD). Patients were included in the analysis if they started cART between 1996 and 2013 with at least one CD8 measurement within 6 months prior to cART initiation and at least one CD8 and viral load (VL) measurement beyond 6 months after starting cART. We defined VF as VL ≥400 copies/mL after 6 months on cART. Elevated CD8 was defined as CD8 ≥1200 cells/μL. Time to VF was modeled using Cox regression analysis, stratified by site.In total, 2475 patients from 19 sites were included in this analysis, of whom 665 (27%) experienced VF in the first 4 years of cART. The overall rate of VF was 12.95 per 100 person-years. In the multivariate model, the most recent elevated CD8 was significantly associated with a greater hazard of VF (HR = 1.35, 95% CI 1.14-1.61; P = 0.001). However, the sensitivity analysis showed that time-lagged CD8 measured at least 6 months prior to our virological endpoint was not statistically significant (P = 0.420).This study indicates that the relationship between the most recent CD8 count and VF was possibly due to the CD8 cells reacting to the increase in VL rather than causing the VL increase itself. However, CD8 levels may be a useful indicator for VF in HIV-infected patients after starting cART.

Increased Antiretroviral Therapy Use and Virologic Suppression in the Bronx in the Context of Multiple HIV Prevention Strategies

Multiple population-based HIV prevention strategies from national, state, local, and institutional levels have been implemented in the Bronx, which has one of the highest HIV prevalences in the U.S. We examined changes in antiretroviral therapy (ART) use and associated outcomes between 2007 and 2014 among patients seen at one of >20 outpatient clinics affiliated with the largest Bronx HIV care provider. Among eligible HIV-infected patients age ≥13 years, we examined annual trends in ART use, mean HIV RNA level, and virologic suppression (<200 copies/ml) overall and among prespecified subgroups. In a subset with suppressed HIV RNA at the end of each year, we determined the percentage whose levels remained suppressed within the next year. Regression models assessed disparities in outcomes. Among 7,196 patients (median age 50, 47% Hispanic, 45% black), we identified consistent increases over time in the percent prescribed ART (78% in 2007 to 93% in 2014) and with virologic suppression (58% to 80%), as mean HIV RNA decreased (351 to 73 copies/ml) (all p < .001). Sustained virologic suppression improved markedly beginning in 2011, coinciding with local test-and-treat initiatives and adoption of expanded treatment guidelines. While disparities among population groups were most pronounced for sustained virologic suppression, those aged 13-24 fared relatively poorly for all outcomes examined (e.g., rate ratio 0.57 for virologic suppression, 95% confidence interval 0.52-0.62, vs. age 65+). Population-wide HIV prevention strategies coincided with improvements in virologic suppression among most population groups. However, more attention is needed to address continued disparities in the HIV care continuum among young people.

Efficacy of generic highly active antiretroviral therapy in HIV-1 infected individuals in Nigeria

CD4 T lymphocyte and plasma HIV RNA parameters have been used to monitor disease progression, and predict clinical course in HIV infection. Initial evaluation of these parameters was conducted in the western countries where accessible ARVs, circulating HIV subtypes and mode of transmission are different from the situation in Nigeria. This study appraised these parameters, and efficacy of generic ARVs. Consenting 106 HIV infected ARV naïve patients were enrolled. CD4 T lymphocyte and plasma HIV RNA levels were determined at interval for 24 months. Ninety eight (92.5%) of the patients who completed the follow up in strict adherence to therapy guideline were included in the analysis. Baseline median CD4 T lymphocyte increased from 114 (Range: 6-330) to highest 357 (Range: 15-1036) cells/ μ L at 18 months of therapy, while baseline median plasma viral RNA declined from 4.6 (Range: 2.6-6.0) Log10 copies/mL to undetectable level within three months of therapy. Significant CD4 T-cell restoration and plasma viral RNA decline in the study population demonstrate efficacy of the generic HAART. The importance of combined use of both parameters for evaluation of immunologic and virologic responses to ART was confirmed.

Impact of low-level viraemia on virological failure in HIV-1-infected patients with stable antiretroviral treatment

BACKGROUND

Low-level viraemia (LLV) occurs in 20-40% of patients achieving viral suppression with antiretroviral therapy (ART). The risk of virological failure (VF: confirmed HIV RNA >200 copies/ml) in these patients is still a matter of debate.

METHODS

This is a prospective cohort study in HIV-infected adults attending the HIV clinic of a tertiary care hospital in Spain. Patients with HIV RNA <25 copies/ml and stable ART for at least 6 months presenting LLV (defined as HIV RNA between 25-1,000 copies/ml) from January 2011 to January 2013 were included and followed until VF or end of follow-up in June 2014.

RESULTS

A total of 300 out of 1,733 (17.3%) patients with undetectable viraemia for 4.2 years showed LLV: 25-50 copies/ml in 167 (55.7%) patients, 51-200 copies/ml in 111 (37%) and 201-1,000 copies/ml in 22 (7.3%) cases. After a median follow-up of 2.6 years, 23 (7.7%) patients presented VF. No patient with a single or multiple unconfirmed LLV went on to develop VF. HIV RNA >200 copies/ml (HR 59.6; 95% CI 15.7, 227), ritonavir-boosted protease inhibtor (PI/r)-based dual therapy (HR 10.2; 95% CI 2.1, 49.8) and PI/r monotherapy (HR 7.9; 95% CI 1.4, 43.3) were associated with VF. Persistent LLV, defined as HIV RNA <200 copies/ml in at least three consecutive samples, for at least 12 weeks, was detected in 27 (1.6%) patients and 14 (51.9%) of those evolved to VF.

CONCLUSIONS

Nearly one-fifth of patients on suppressive ART showed LLV and 8% of them developed VF. HIV RNA >200 copies/ml was the strongest predictor of VF. Over half of patients with persistent viraemia <200 copies/ml showed VF.

True durability: HIV virologic suppression in an urban clinic and implications for timing of intensive adherence efforts and viral load monitoring

Although the majority of HIV-infected patients who begin potent antiretroviral therapy should expect long-term virologic suppression, the realities in practice are less certain. Durability of viral suppression was examined to define the best timing of targeted adherence strategies and intensive viral load monitoring in an urban clinic population with multiple challenges to ART adherence. We examined the risk of viral rebound for patients who achieved two consecutive viral loads lower than the lower limit of quantification (LLOQ) within 390 days. For 791 patients with two viral loads below the LLOQ, viral rebound >LLOQ from the first viral load was 36.9 % (95 % CI 32.2-41.6) in the first year, 26.9 % (95 % CI 21.7-32.1) in the year following one year of viral suppression, and 24.6 % (95 % CI 18.4-30.9) in the year following 2 years of viral suppression. However, for patients with CD4 ≥300 cells/µl who had 3-6 years of virologic suppression, the risk of viral rebound was very low. At the population level, the risk of viral rebound in a complex urban clinic population is surprisingly high even out to 3 years. Intensified monitoring and adherence efforts should target this high risk period. Thereafter, confidence in truly durable virologic suppression is improved.

Antiretroviral therapy: treatment-experienced individuals

Antiretroviral therapy (ART)-experienced individuals may choose to modify their regimens because of suboptimal virologic response, poor tolerability, convenience, or to minimize interactions with other medications or food. Constructing a new regimen for any of these reasons requires a thorough review of prior antiretroviral drug use and available drug resistance results. This article summarizes the strategies used in managing the ART-experienced individual who is considering a modification in therapy at the time of suboptimal virologic response or while virologically suppressed on a stable regimen.

[Clinical and biological effectiveness of antiretroviral therapy in the ANRS 1215 cohort]

In 1998, the cohort ANRS 1215 was launched in Senegal with one of the first African antiretroviral treatment programs. Four hundred forty four HIV-infected adults started on ART were included between 1998 and 2004, and followed up to 2010. Mortality before 6 months was 15.6/100 person-year (PY) and associated to the initial disease severity. It decreased to 3.36/100 PY thereafter. The cumulative risks of virologic failure at 60 months and of drug resistance at 48 months were 25% and 16%, respectively.

Risk of virological failure and drug resistance during first and second-line antiretroviral therapy in a 10-year cohort in Senegal: results from the ANRS 1215 cohort

BACKGROUND

In 1998, Senegal launched one of Africa's first antiretroviral therapy (ART) programs. Since then, the number of treated patients in Africa has substantially increased thanks to simplification in treatment management. Although good outcomes over the first years of ART have been observed in sub-Saharan Africa, little is known about the long-term (>5 years) risks of virological failure and drug resistance and about second-line treatment response.

METHODS

Patients from the ANRS-1215 cohort in Senegal, started with either one nonnucleoside reverse transcriptase inhibitor or indinavir, a first-generation nonboosted protease inhibitor, followed for >6 months and having >1 viral load (VL) measurement were included. Virological failure was defined as 2 consecutive VL measurements >1000 copies/mL.

RESULTS

Of the 366 patients included, 89% achieved a VL <500 copies/mL. The risk of virological failure at 12, 24, and 60 months was 5%, 16%, and 25%, being higher in younger patients (P = 0.05), those receiving a protease inhibitor-containing regimen (P = 0.05), and those with lower adherence (P = 0.03). The risk of resistance to any drug at 12, 24, and 60 months was 3%, 11%, and 18%. After virological failure, 60% of the patients were switched to second-line treatments. Although 81% of the patients achieved virological success, the risk of virological failure was 27% at 24 months, mostly in patients with multiple resistances.

CONCLUSIONS

In this cohort, virological outcomes for first-line treatments were good compared with those from high-resource settings. However, the rate of virological failure for second-line treatment was high, probably because of accumulation of resistances.

Second generation HIV protease inhibitors against resistant virus

BACKGROUND

The AIDS epidemic has spread around the world at an alarming rate. Although the first generation of HIV protease inhibitors, including indinavir, nelfinavir, saquinavir, ritonavir and amprenavir, were initially effective against HIV infection, the fast emerging resistance to these agents has been a substantial and persistent problem in the treatment of AIDS. Attempts to address the resistance issue with 'salvage therapy' consisting of high doses of multiple protease inhibitors have only been moderately successful owing to the high level of cross-resistance and toxicities associated with the protease inhibitors.

OBJECTIVE

To study the second generation HIV protease inhibitors against resistant virus.

METHOD

This review highlights new developments achieved by various organizations to address the challenge of high level resistance of current therapies since 2000.

CONCLUSION

All second generation protease inhibitors used in patients who experienced extensive treatment require ritonavir as a pharmacological boosting agent to increase the drug level in the plasma, but there is toxicity associated with such a practice. Accordingly, there remains a need for new protease inhibitors with improved effectiveness against the resistant viral variants. A third generation protease inhibitor will require no boosting agent while maintaining high potency against resistant virus.

Patients' demographic and clinical characteristics and level of care associated with lost to follow-up and mortality in adult patients on first-line ART in Nigerian hospitals

Introduction

Clinical outcome is an important determinant of programme success. This study aims to evaluate patients’ baseline characteristics as well as level of care associated with lost to follow-up (LTFU) and mortality of patients on antiretroviral treatment (ART).

Methods

Retrospective cohort study using routine service data of adult patients initiated on ART in 2007 in 10 selected hospitals in Nigeria. We captured data using an electronic medical record system and analyzed using Stata. Outcome measures were probability of being alive and retained in care at 12, 24 and 36 months on ART. Potential predictors associated with time to mortality and time to LTFU were assessed using competing risks regression models.

Results

After 12 months on therapy, 85% of patients were alive and on ART. Survival decreased to 81.2% and 76.1% at 24 and 36 months, respectively. Median CD4 count for patients at ART start, 12, 18 and 24 months were 152 (interquartile range, IQR: 75 to 242), 312 (IQR: 194 to 450), 344 (IQR: 227 to 501) and 372 (IQR: 246 to 517) cells/µl, respectively. Competing risk regression showed that patients’ baseline characteristics significantly associated with LTFU were male (adjusted sub-hazard ratio, sHR=1.24 [95% CI: 1.08 to 1.42]), ambulatory functional status (adjusted sHR=1.25 [95% CI: 1.01 to 1.54]), World Health Organization (WHO) clinical Stage II (adjusted sHR=1.31 [95% CI: 1.08 to 1.59]) and care in a secondary site (adjusted sHR=0.76 [95% CI: 0.66 to 0.87]). Those associated with mortality include CD4 count <50 cells/µl (adjusted sHR=2.84 [95% CI: 1.20 to 6.71]), WHO clinical Stage III (adjusted sHR=2.67 [95% CI: 1.26 to 5.65]) and Stage IV (adjusted sHR=5.04 [95% CI: 1.93 to 13.16]) and care in a secondary site (adjusted sHR=2.21 [95% CI: 1.30 to 3.77]).

Conclusions

Mortality was associated with advanced HIV disease and care in secondary facilities. Earlier initiation of therapy and strengthening systems in secondary level facilities may improve retention and ultimately contribute to better clinical outcomes.

Comparison of HIV-1 viral load assay performance in immunological stable patients with low or undetectable viremia

The goal of antiretroviral therapy is reduction in morbidity and mortality via suppression of human immunodeficiency virus (HIV) viral load (VL) to undetectable levels. VL assay sensitivity has improved over time, but the reproducibility and clinical importance of VL results marginally higher than the limit of detection (LoD) are uncertain. We assessed the reproducibility and concordance of low VL results obtained with the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 version 2.0 (CAP-CTM) and the Abbott RealTime (m2000) HIV-1 assays, using longitudinal specimens from HIV-1-infected patients with low VL (<300 copies/ml) and stable CD4+ cell counts. Based on replicate testing of 3 specimens, coefficients of variation for log-transformed VL results were 5-8 % for m2000 and 9-10 % for CAP-CTM. The concordance between assays in specimens from patients with previously undetectable, detectable but not quantifiable VL, or variable (undetectable/detectable but not quantifiable VL) results over time was 90, 56, and 56 %, respectively. Correlation between results for specimens with quantifiable VL (initially 40-300 copies/ml) was moderate (R (2) = 0.48) with significantly higher results for CAP-CTM and a mean difference (CAP-CTM minus m2000) of 0.10 log(10) copies/ml. T-cell activation (CD8+/CD38+ percentage) in patients with low VL was initially higher than in patients with undetectable VL, and then decreased to equivalent levels over time. These results indicate that residual viremia at levels slightly above the LoD have no negative effect on T-cell activation.

Calendar time trends in the incidence and prevalence of triple-class virologic failure in antiretroviral drug-experienced people with HIV in Europe

BACKGROUND

Despite the increasing success of antiretroviral therapy (ART), virologic failure of the 3 original classes [triple-class virologic failure, (TCVF)] still develops in a small minority of patients who started therapy in the triple combination ART era. Trends in the incidence and prevalence of TCVF over calendar time have not been fully characterised in recent years.

METHODS

Calendar time trends in the incidence and prevalence of TCVF from 2000 to 2009 were assessed in patients who started ART from January 1, 1998, and were followed within the Collaboration of Observational HIV Epidemiological Research Europe (COHERE).

RESULTS

Of 91,764 patients followed for a median (interquartile range) of 4.1 (2.0-7.1) years, 2722 (3.0%) developed TCVF. The incidence of TCVF increased from 3.9 per 1000 person-years of follow-up [95% confidence interval (CI): 3.7 to 4.1] in 2000 to 8.8 per 1000 person-years of follow-up (95% CI: 8.5 to 9.0) in 2005, but then declined to 5.8 per 1000 person-years of follow-up (95% CI: 5.6 to 6.1) by 2009. The prevalence of TCVF was 0.3% (95% CI: 0.27% to 0.42%) at December 31, 2000, and then increased to 2.4% (95% CI: 2.24% to 2.50%) by the end of 2005. However, since 2005, TCVF prevalence seems to have stabilized and has remained below 3%.

CONCLUSIONS

The prevalence of TCVF in people who started ART after 1998 has stabilized since around 2005, which most likely results from the decline in incidence of TCVF from this date. The introduction of improved regimens and better overall HIV care is likely to have contributed to these trends. Despite this progress, calendar trends should continue to be monitored in the long term.

Social and environmental predictors of plasma HIV RNA rebound among injection drug users treated with antiretroviral therapy

INTRODUCTION

Evidence is needed to improve HIV treatment outcomes for individuals who use injection drugs (IDU). Although studies have suggested higher rates of plasma viral load (PVL) rebound among IDU on antiretroviral therapy (ART), risk factors for rebound have not been thoroughly investigated.

METHODS

We used data from a long-running community-recruited prospective cohort of IDU in Vancouver, Canada, linked to comprehensive ART and clinical monitoring records. Using proportional hazards methods, we modeled the time to confirmed PVL rebound above 1000 copies per milliliter among IDU on ART with sustained viral suppression, defined as 2 consecutive undetectable PVL measures.

RESULTS

Between 1996 and 2009, 277 individuals had sustained viral suppression. Over a median follow-up of 32 months, 125 participants (45.1%) experienced at least 1 episode of virologic failure for an incidence of 12.6 [95% confidence interval (CI): 10.5 to 15.0] per 100 person-years. In a multivariate model, PVL rebound was independently associated with sex-trade involvement [adjusted hazard ratio (AHR) = 1.40, 95% CI: 1.08 to 1.82) and recent incarceration (AHR = 1.83, 95% CI: 1.33 to 2.52). Methadone maintenance therapy (AHR = 0.79, 95% CI: 0.66 to 0.94) was protective. No measure of illicit drug use was predictive.

CONCLUSIONS

In this setting of free ART, several social and environmental factors predicted higher risks of viral rebound among IDU, including sex-trade involvement and incarceration. These findings should help inform efforts to identify individuals at risk of viral rebound and targeted interventions to treat and retain individuals in effective ART.

Projected life expectancy of people with HIV according to timing of diagnosis

BACKGROUND AND OBJECTIVES

Effective antiretroviral therapy (ART) has contributed greatly toward survival for people with HIV, yet many remain undiagnosed until very late. Our aims were to estimate the life expectancy of an HIV-infected MSM living in a developed country with extensive access to ART and healthcare, and to assess the effect of late diagnosis on life expectancy.

METHODS

A stochastic computer simulation model of HIV infection and the effect of ART was used to estimate life expectancy and determine the distribution of potential lifetime outcomes of an MSM, aged 30 years, who becomes HIV positive in 2010. The effect of altering the diagnosis rate was investigated.

RESULTS

Assuming a high rate of HIV diagnosis (median CD4 cell count at diagnosis, 432  cells/μl), projected median age at death (life expectancy) was 75.0 years. This implies 7.0 years of life were lost on average due to HIV. Cumulative risks of death by 5 and 10 years after infection were 2.3 and 5.2%, respectively. The 95% uncertainty bound for life expectancy was (68.0,77.3) years. When a low diagnosis rate was assumed (diagnosis only when symptomatic, median CD4 cell count 140  cells/μl), life expectancy was 71.5 years, implying an average 10.5 years of life lost due to HIV.

CONCLUSION

If low rates of virologic failure observed in treated patients continue, predicted life expectancy is relatively high in people with HIV who can access a wide range of antiretrovirals. The greatest risk of excess mortality is due to delays in HIV diagnosis.

Plasma HIV-1 RNA detection below 50 copies/ml and risk of virologic rebound in patients receiving highly active antiretroviral therapy

BACKGROUND

Plasma human immunodeficiency virus type 1 (HIV-1) RNA suppression <50 copies/mL is regarded as the optimal outcome of highly active antiretroviral therapy (HAART). Current viral load (VL) assays show increased sensitivity, but the significance of RNA detection <50 copies/mL is unclear.

METHODS

This study investigated the virologic outcomes of 1247 patients with VL <50 copies/mL at an arbitrary time point during HAART (= T0), according to whether the actual, unreported (T0)VL was 40-49 copies/mL, RNA detected <40 copies/mL (RNA(+)), or RNA not detected (RNA(-)), as measured by the Abbott Real Time assay. Predictors of rebound >50 and >400 copies/mL over 12 months following T0 were analyzed with Cox proportional hazards models incorporating the (T0)VL and demographic and clinical data.

RESULTS

Rebound rates >50 copies/mL were 34.2% for (T0)VL 40-49 copies/mL, 11.3% for RNA(+), and 4.0% for RNA(-); rebound rates >400 copies/mL were 13.0%, 3.8%, and 1.2%, respectively. The adjusted hazard ratios for rebound >50 copies/mL were 4.67 (95% confidence interval, 2.91-7.47; P < .0001) and 1.97 (1.25-3.11; P < .0001) with (T0)VL 40-49 copies/mL and RNA(+), respectively, relative to RNA(-), and 6.91 (2.90-16.47; P < .0001) and 2.88 (1.24-6.69; P < .0001), respectively, for rebound >400 copies/mL. The association was independent of adherence levels.

CONCLUSIONS

In treated patients monitored by RealTime, a VL of 40-49 copies/mL and, to a lesser extent, RNA detection <40 copies/mL predict rebound >50 and >400 copies/mL independently of other recognized determinants. The goal of HAART may need to be revised to a lower cutoff than 50 copies/mL.

Economic and health-related quality-of-life (HRQoL) comparison of lopinavir/ritonavir (LPV/r) and atazanavir plus ritonavir (ATV+RTV) based regimens for antiretroviral therapy (ART)-naïve and -experienced United Kingdom patients in 2011

BACKGROUND

Using a United Kingdom (UK)-based National Health Services perspective for 2011 this study first estimated the cost-effectiveness and budget impact implications for lopinavir/ritonavir (LPV/r) vs atazanavir plus ritonavir (ATV+RTV) treatment of antiretroviral therapy (ART)-naïve patients and secondly examined the long-term health-related quality-of-life (HRQoL) and economic implications for LPV/r vs ATV+RTV treatment of ART-experienced patients.

METHODS

A previously published Markov model that integrates epidemiological data of human immunodeficiency virus (HIV) with predictors of coronary heart disease (CHD) was modified under a clearly specified set of assumptions to reflect viral load (VL) suppression profiles and other differences for these two regimens, applying results from the CASTLE study in ART-naïve patients and using data from BMS-045 in ART-experienced patients. ART costs were referenced to current (2011) pricing guidelines in the UK. Medical care costs reflected UK treatment patterns and relevant drug pricing. Costs and outcomes were discounted at 3.5% per year. Costs are expressed in British pounds (£) and life expectancy in quality-adjusted life years (QALYs).

RESULTS

In the ART-naïve subjects, the model predicted a marginal improved life expectancy of 0.031 QALYs (11 days) for the ATV+RTV regimen as a result of predicted CHD outcomes based on lower increases in cholesterol levels compared with the LPV/r regimen. The model demonstrated cost savings with the LPV/r regimen. The total lifetime cost savings was £4070 per patient for the LPV/r regimen. LPV/r saved £2133 and £3409 per patient at 5 and 10 years, respectively. Referenced to LPV/r, the incremental cost-effectiveness ratio (ICER) for ATV+RTV was £149,270/QALY. For ART-experienced patients VL suppression differences favored LPV/r, while CHD risk associated with elevated total cholesterol marginally favored ATV+RTV, resulting in a net improvement in life expectancy of 0.31 QALYs (106 days) for LPV/r. Five-year costs were £5538 per patient greater for ATV+RTV, with a discounted lifetime saving of £1445 per LPV/r patient. LPV/r was modestly dominant economically, producing better outcomes and cost savings.

LIMITATIONS

The limitations of this study include uncertainty related to how well the model's assumptions capture current practice, as well as the validity of the model parameters used. This study was limited to using aggregated data in the public domain from the two clinical trials. Thus, some of the model parameters may reflect limitations due to trial design and data aggregation bias. This study has attempted to illuminate the effect of these limitations by presenting the results of the comprehensive sensitivity analysis.

CONCLUSIONS

Based on 2011 costs of HIV in the UK and the published efficacy data from the CASTLE and BMS-045 studies, ATV+RTV-based regimens are not expected to be a cost-effective use of resources for ART-naïve patients similar to patients in the CASTLE study, nor for ART-experienced patients based on the only published comparison of ATV+RTV and LPV/r.

Disparities in antiretroviral treatment: a comparison of behaviorally HIV-infected youth and adults in the HIV Research Network

OBJECTIVES

Increasing numbers of youth are becoming HIV-infected and need highly active antiretroviral therapy (HAART). We hypothesized that behaviorally HIV-infected youth (BIY) ages 18 to 24 years are less likely than adults (25 years or older) to receive HAART and, once initiated, more likely to discontinue their first HAART regimen.

METHODS

Longitudinal analysis of treatment-naïve patients (age 18 years or older) meeting criteria for HAART and followed at HIV Research Network sites (2002-2008). Time from meeting criteria to HAART initiation and duration on first regimen were assessed using Cox proportional hazards regression.

RESULTS

A total of 3127 (268 youth, 2859 adult) treatment-naïve, HIV-infected patients met criteria. BIY were more likely to be black (66.8% vs 51.1%; P < 0.01) and less likely to identify injection drug use HIV risk (1.1% vs 8.8%; P < 0.01) than adults 25 years of age or older. Nearly 69% of BIY started HAART versus 79% of adults (P < 0.001). Adults 25 to 29 years of age (adjusted hazards ratio [AHR], 1.39; 95% confidence interval [CI], 1.12-1.73) and 50 years of age or older (AHR, 1.24; 95% CI, 1.00-1.54), but not 30 to 49 years (AHR, 1.19; 95% CI, 0.99-1.44) were more likely to initiate HAART than BIY. Attending four or more HIV provider visits within 1 year of meeting criteria was associated with HAART initiation (AHR, 1.91; 1.70-2.14). CD4 200 to 350 versus less than 200 cells/mm (AHR, 0.57; 95% CI, 0.52-0.63), and injection drug use (AHR, 0.80; 95% CI, 0.69-0.92) were associated with a lower likelihood of HAART initiation. There were no age-related differences in duration of the first regimen.

CONCLUSION

BIY are less likely to start HAART when meeting treatment criteria. Addressing factors associated with this disparity is critical to improving care for youth.

Elevated CD8 counts during HAART are associated with HIV virologic treatment failure

OBJECTIVE

To evaluate whether elevated CD8 counts are associated with increased risk of virologic treatment failure in HIV-infected individuals.

DESIGN

Retrospective cohort study.

METHODS

US Military HIV Natural History Study participants who initiated highly active antiretroviral therapy (HAART) in 1996-2008 had 6- and 12-month post-HAART HIV RNA <400 copies per milliliter, ≥ 2 subsequent HIV viral loads and a baseline CD8 count were eligible (n = 817). Baseline was 12 months after the start of HAART, virologic failure (VF) was defined as confirmed HIV RNA ≥ 400 copies per milliliter, and CD8 counts ≥ 1200 cells per cubic millimeter were considered elevated. Cox models were used to examine the effect of baseline and time-updated CD8 counts on VF.

RESULTS

There were 216 failures for a rate of 5.6 per 100 person-years [95% confidence interval (CI): 4.9 to 6.4]. Among those initiating HAART in 2000-2008, the participants with elevated baseline CD8 counts had significantly greater risk of VF compared with those with baseline CD8 counts ≤ 600 cells per cubic millimeter [hazard ratio (HR) = 2.68, 95% CI: 1.13 to 6.35]. The participants with elevated CD8 counts at >20% of previous 6-month follow-up visits had a greater risk of failure at the current visit than those who did not (HR = 1.53, 95% CI: 1.14 to 2.06). Those with CD8 counts that increased after the start of HAART had a greater risk of failure than those with CD8 counts that decreased or remained the same (HR = 1.59, 95% CI: 1.19 to 2.13).

CONCLUSIONS

Initial or serial elevated CD8 counts while on HAART or an increase in CD8 counts from HAART initiation may be early warnings for future treatment failure.

Non-linear mixed effects modeling of antiretroviral drug response after administration of lopinavir, atazanavir and efavirenz containing regimens to treatment-naïve HIV-1 infected patients

The objective of this analysis was to compare three methods of handling HIV-RNA data below the limit of quantification (LOQ) when describing the time-course of antiretroviral drug response using a drug-disease model. Treatment naïve Scandinavian HIV-positive patients (n = 242) were randomized to one of three study arms. Two nucleoside reverse transcriptase inhibitors were administrated in combination with 400/100 mg lopinavir/ritonavir twice daily, 300/100 mg atazanavir/ritonavir once a day or 600 mg efavirenz once a day. The viral response was monitored at screening, baseline and at 1, 2, 3, 4, 12, 24, 48, 96, 120, and 144 weeks after study initiation. Data up to 400 days was fitted using a viral dynamics non-linear mixed effects drug-disease model in NONMEM. HIV-RNA data below LOQ of 50 copies/ml plasma (39%) was omitted, replaced by LOQ/2 or included in the analysis using a likelihood-based method (M3 method). Including data below LOQ using the M3 method substantially improved the model fit. The drug response parameter expressing the fractional inhibition of viral replication was on average (95% CI) estimated to 0.787 (0.721-0.864) for lopinavir and atazanavir treatment arms and 0.868 (0.796-0.923) for the efavirenz containing regimen. At 400 days after treatment initiation 90% (76-100) of the lopinavir and atazanavir treated patients were predicted to have undetectable viral levels and 96% (89-100%) for the efavirenz containing treatment. Including viral data below the LOQ rather than omitting or replacing data provides advantages such as better model predictions and less biased parameter estimates which are of importance when quantifying antiretroviral drug response.

Efficient monitoring of HIV-1 vertically infected children in Kenya on first-line antiretroviral therapy

BACKGROUND

Worldwide access to antiretroviral therapy (ART) in low- and middle-income countries has significantly increased. Although this presents better treatment options for HIV-infected individuals, the challenge of monitoring ART in these settings still remains.

OBJECTIVE

To investigate efficient and cost-effective criteria for assessing ART failure among HIV-1-infected children on first-line ART in resource-limited settings.

STUDY DESIGN

Retrospective analysis of 75 HIV-1 vertically infected Kenyan children with a follow-up period of 24 months after initiating ART. Plasma viral load, peripheral CD4(+)T-cell counts and HIV-1 drug-resistance mutations were monitored biannually.

RESULTS

Plasma viral load (VL) was suppressed to undetectable level or more than 1.5 log(10) from baseline levels in 53 (70.7%) children within 24 months. VL in the remaining 22 (29.3%) children was not suppressed significantly. Of the 22 children, 21 were infected with HIV-1 strains that developed drug-resistance mutations; 9 within 12 months and 12 between 12 and 24 months. Among the 53 who were successfully treated, VL was suppressed in 33 within 12 months and in 20 between 12 and 24 months. There was no significant difference in VL at baseline and the change of CD4(+)T-cell counts after initiating ART between those treated successfully and the failure groups.

CONCLUSION

After initiating ART, children may require longer times to achieve complete viral suppression. Plasma viral load testing 24 months after initiating ART could be used to differentiate ART failures among HIV-1 vertically infected children in resource-limited settings. Additionally, drug resistance testing, if affordable, would be helpful in identifying those failing therapy and in choosing second-line regimens.

Cost effectiveness of atazanavir-ritonavir versus lopinavir-ritonavir in treatment-naïve human immunodeficiency virus-infected patients in the United States

OBJECTIVE

To evaluate lifetime cost effectiveness of atazanavir-ritonavir (ATV + r) versus lopinavir-ritonavir (LPV/r), both with tenofovir-emtricitabine, in US HIV-infected patients initiating first-line antiretroviral therapy.

METHODS

A Markov microsimulation model was developed to calculate quality-adjusted life-years (QALYs) based on CD4 and HIV RNA levels, coronary heart disease (CHD), AIDS, opportunistic infections (OIs), diarrhea, and hyperbilirubinemia. A million-member cohort of HIV-1-infected, treatment-naïve adults progressed at 3-month intervals through eight health states. Baseline characteristics, virologic suppression, cholesterol changes, and diarrhea and hyperbilirubinemia rates were based on 96-week CASTLE trial results. HIV mortality, OI rates, adherence, costs, utilities, and CHD risk were from literature and experts.

LIMITATIONS

The incremental cost-effectiveness ratio (ICER) may be overestimated because the ATV + r treatment effect was based on an intention-to-treat analysis. The QALY weights used for diarrhea, hyperbilirubinemia, and CHD events are uncertain; however, the ICER remained < $50,000/QALY when these values were varied in sensitivity analyses.

RESULTS

ATV + r patients received first-line therapy longer than LPV/r patients (97.3 vs. 70.7 months), had longer quality-adjusted survival (11.02 vs. 10.76 years), similar overall survival (18.52 vs. 18.51 years), and higher costs ($275,986 vs. 269,160). ATV+r [corrected] patients had lower rates of AIDS (19.08 vs. 20.05 cases/1000 patient-years), OIs (0.44 vs.0.52), diarrhea (1.27 vs. 6.26), and CHD events(5.44 vs. 5.51), but higher hyperbilirubinemia rates (6.99 vs. 0.25. ATV + r added 0.26 QALYs at a cost of $6826, for $26,421/QALY.

CONCLUSIONS

By more effectively reducing viral load with less gastrointestinal toxicity and a better lipid profile, ATV + r lowered rates of AIDS and CHD, increased quality-adjusted survival, and was cost effective (< $50,000/QALY) compared with LPV/r.

Broadening the perspective when assessing evidence on boosted protease inhibitor-based regimens for initial antiretroviral therapy

Several national and international guidelines recommend the use of antiretroviral therapy containing a protease inhibitor (PI) with ritonavir (RTV) boosting for human immunodeficiency virus (HIV)-infected treatment-naïve patients. RTV-boosted PIs such as lopinavir (LPV/r), atazanavir (ATV + RTV), darunavir (DRV + RTV), fosamprenavir (FPV + RTV), and saquinavir (SQV + RTV) are usually recommended in regimens for initial therapy. The guideline recommendations are generally based on the clinical efficacy of the regimens. A broadened perspective of assessing the evidence related to selection of a PI for optimal first-line therapy might consider additional factors for evaluation, such as effectiveness in actual clinical practice and cost-effectiveness of individual drugs in formulating recommendations. Among the guideline-recommended PIs, LPV/r is one of the earliest PIs approved, has been a well-recognized boosted PI for treatment-naïve patients in all guidelines, and demonstrates the most evidence on long-term clinical and economic effectiveness. Studies have shown its efficacy in various controlled and real-world settings in different populations, the relationship of adherence to virologic efficacy, and the implications of resistance when used in sequence with other PI regimens. In the absence of published evidence for other guideline-recommended PIs that will greatly facilitate a fully transparent, comparative effectiveness evaluation, the cumulative evidence from this broader perspective indicates all PIs should not be viewed as equally safe and effective across all patients for initial therapy, nor should any single PI within the class be considered preferred for all treatment-naïve patients.

Long-term efavirenz autoinduction and its effect on plasma exposure in HIV patients

We investigated the influence of gender and pharmacogenetic variations on long-term efavirenz autoinduction and disposition among patients with HIV in Tanzania (N = 129). Plasma concentrations (at 16 h) of efavirenz and 8-hydroxyefavirenz were quantified at weeks 4 and 16 of therapy. Genotyping was performed to identify cytochrome P450 (CYP) 2B6*6, CYP3A5*3, *6, and *7, and ABCB1-3435 C/T genotypes. There were reductions in the median efavirenz concentration (Wilcoxon matched-pair test P < 0.001) and efavirenz/8-hydroxyefavirenz ratio (P < 0.001) by 19 and 32%, respectively, at week 16 as compared with week 4. The proportion of patients with efavirenz concentration <1 µg/ml at week 16 was higher by 67, 25, and 5% in CYP2B6*1/*1, *1/*6, and *6/*6 genotypes, respectively. The defined therapeutic range based on observed plasma concentrations is affected by the time point of sampling and the CYP2B6 genotype. The effect of efavirenz autoinduction on reducing plasma exposure continues up to week 16 and predominantly affects CYP2B6 extensive metabolizers. Among CYP2B6 slow metabolizers, the presence of a CYP3A5 genotype allele is associated with greater effects of efavirenz autoinduction on plasma concentrations of the drug. The cumulative induction may influence the long-term antiretroviral therapy outcome, particularly in CYP2B6*1 carriers.

Substitution of raltegravir for ritonavir-boosted protease inhibitors in HIV-infected patients: the SPIRAL study

BACKGROUND

Switching to raltegravir in selected patients treated with ritonavir-boosted protease inhibitors may result in similar efficacy and lower plasma lipids.

METHODS

SPIRAL is a 48-week multicentre, open-label trial in which HIV-infected adults with less than 50 copies/ml of plasma HIV RNA for at least the previous 6 months on ritonavir-boosted protease inhibitor-based therapy were randomized (1: 1) to switch from the ritonavir-boosted protease inhibitor to raltegravir or to continue on ritonavir-boosted protease inhibitor-based therapy. Primary endpoint was the proportion of patients free of treatment failure (noncompleter = failure) at 48 weeks. SPIRAL study was powered to show noninferior efficacy of raltegravir-based therapy with a margin of -12.5%.

RESULTS

Two hundred and seventy-three patients assigned to switch to raltegravir (n = 139) or to continue ritonavir-boosted protease inhibitor (n = 134) were included in the efficacy analysis. At 48 weeks, 89.2% (raltegravir-based therapy) and 86.6% (ritonavir-boosted protease inhibitor-based therapy) of the patients remained free of treatment failure [difference 2.6%; 95% confidence interval (CI) -5.2 to 10.6]. A total of 96.9% (raltegravir-based therapy) and 95.1% (ritonavir-boosted protease inhibitor-based therapy) of the patients remained free of virological failure (difference 1.8%; 95% CI -3.5 to 7.5). Switching to raltegravir was associated with significant decreases in plasma lipids and total-to-HDL cholesterol ratio relative to continuing ritonavir-boosted protease inhibitor. Severe adverse events and study drug discontinuations due to any adverse event occurred in 4 and 2% of the patients in each group.

CONCLUSION

In patients with sustained virological suppression on ritonavir-boosted protease inhibitor-based therapy, switching from ritonavir-boosted protease inhibitor to raltegravir demonstrated noninferior efficacy and resulted in a better lipid profile at 48 weeks than continuing ritonavir-boosted protease inhibitor.

Predicting virologic failure in an HIV clinic

BACKGROUND

We sought to use data captured in the electronic health record (EHR) to develop and validate a prediction rule for virologic failure among patients being treated for infection with human immunodeficiency virus (HIV).

METHODS

We used EHRs at 2 Boston tertiary care hospitals, Massachusetts General Hospital and Brigham and Women's Hospital, to identify HIV-infected patients who were virologically suppressed (HIV RNA level < or = 400 copies/mL) on antiretroviral therapy (ART) during the period from 1 January 2005 through 31 December 2006. We used a multivariable logistic model with data from Massachusetts General Hospital to derive a 1-year virologic failure prediction rule. The model was validated using data from Brigham and Women's Hospital.We then simplified the scoring scheme to develop a clinical prediction rule.

RESULTS

The 1-year virologic failure prediction model, using data from 712 patients from Massachusetts General Hospital, demonstrated good discrimination (C statistic, 0.78) and calibration (chi(2)= 6.6; P= .58). The validation model, based on 362 patients from Brigham and Women's Hospital, also showed good discrimination (C statistic, 0.79) and calibration (chi(2)= 1.9; P= .93). The clinical prediction rule included 7 predictors (suboptimal adherence, CD4 cell count < 100 cells/microL, drug and/or alcohol abuse, highly ART experienced, missed > or = 1 appointment, prior virologic failure, and suppressed < or = 12 months) and appropriately stratified patients in the validation data set into low-, medium-, and high-risk groups, with 1-year virologic failure rates of 3.0%, 13.0%, and 28.6%, respectively.

CONCLUSIONS

A risk score based on 7 variables available in the EHR predicts HIV virologic failure at 1 year and could be used for targeted interventions to improve outcomes in HIV infection.

Defining treatment failure in resource-rich settings

PURPOSE OF REVIEW

To define treatment failure in resource-rich settings; summarizing current guidelines, assays, the significance of detectable viremia, and definitions of treatment failure in clinical and research settings.

RECENT FINDINGS

The goal of treatment should be full viral suppression, even in highly treatment-experienced patients.

SUMMARY

Treatment failure is defined as repeated HIV RNA values above the lower limit of detection of a sensitive assay (usually 50 copies/ml). This criterion is based on evidence that the maximum clinical benefit of antiretroviral therapy is derived by keeping the viral load as low as possible. Full viral suppression should be achievable in all patients, both treatment-naïve and experienced. Transient, low-detectable viremia ('blips') may not predict virologic breakthrough. However, consecutive or higher-level transient viremia is associated with risk of treatment failure. Defining failure by a confirmed HIV RNA more than 50 copies/ml is the most conservative approach, but the use of such low limits of detection in clinical trials may lead to a high false-positive 'failure' rate, thus a definition of 200 copies/ml may be preferable. Variation in clinical trial endpoint definitions creates a challenge for comparing results between studies. For example, using a composite endpoint to define treatment failure may result in a high proportion of 'failures' that are not related to poor virologic response.

History of viral suppression on combination antiretroviral therapy as a predictor of virological failure after a treatment change

OBJECTIVES

HIV-infected persons experience different patterns of viral suppression after initiating combination antiretroviral therapy (cART). The relationship between such differences and risk of virological failure after starting a new antiretroviral could help with patient monitoring strategies.

METHODS

A total of 1827 patients on cART starting at least one new antiretroviral from 1 January 2000 while maintaining a suppressed viral load were included in the analysis. Poisson regression analysis identified factors predictive of virological failure after baseline in addition to traditional demographic variables. Baseline was defined as the date of starting new antiretrovirals.

RESULTS

Four hundred and fifty-one patients (24.7%) experienced virological failure, with an incidence rate (IR) of 7.3 per 100 person-years of follow-up (PYFU) [95% confidence interval (CI) 6.7-8.0]. After adjustment, patients who had rebounded in the year prior to baseline had a 2.4-times higher rate of virological failure after baseline (95% CI 1.77-3.26; P<.0001), while there was no increased incidence in patients whose last viral rebound was >3 years prior to baseline [Incidence rate ratio (IRR) 1.06; 95% CI 0.75-1.50; P=0.73] compared with patients who had never virally rebounded. Patients had an 86% (95% CI 1.36-2.55; P<.0001), 53% (95% CI 1.06-2.04; P=0.02) and 5% (95% CI 0.80-1.38; P=0.72) higher virological failure rate after baseline if they were virally suppressed <50%, 50-70% and 70-90% of the time they were on cART prior to baseline, respectively, compared with those virally suppressed >90% of the time.

DISCUSSION

Intensive monitoring after a treatment switch is required in patients who have rebounded recently or have a low percentage of time suppressed while on cART. Consideration should be given to increasing the provision of adherence counselling.

Cellular levels of HIV unspliced RNA from patients on combination antiretroviral therapy with undetectable plasma viremia predict the therapy outcome

BACKGROUND

Combination antiretroviral therapy (cART), the standard of care for HIV-1 infection, is considered to be successful when plasma viremia remains below the detection limit of commercial assays. Yet, cART fails in a substantial proportion of patients after the apparent success. No laboratory markers are known that are predictive of cART outcome in initial responders during the period of undetectable plasma viremia.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we report the results of a retrospective longitudinal study of twenty-six HIV-infected individuals who initially responded to cART by having plasma viremia suppressed to <50 copies/ml. Eleven of these patients remained virologically suppressed, whereas fifteen experienced subsequent cART failure. Using sensitive methods based on seminested real-time PCR, we measured the levels of HIV-1 proviral (pr) DNA, unspliced (us) RNA, and multiply spliced RNA in the peripheral blood mononuclear cells (PBMC) of these patients at multiple time points during the period of undetectable plasma viremia on cART. Median under-therapy level of usRNA was significantly higher (0.43 log(10) difference, P = 0.0015) in patients who experienced subsequent cART failure than in successfully treated patients. In multivariate analysis, adjusted for baseline CD4(+) counts, prior ART experience, and particular cART regimens, the maximal usRNA level under therapy was the best independent predictor of subsequent therapy failure (adjusted odds ratio [95% CI], 24.4 [1.5-389.5], P = 0.024). The only other factor significantly associated with cART failure was prior ART experience (adjusted odds ratio [95% CI], 12.3 [1.1-138.4], P = 0.042). Levels of usRNA under cART inversely correlated with baseline CD4(+) counts (P = 0.0003), but did not correlate with either baseline usRNA levels or levels of prDNA under therapy.

CONCLUSION

Our data demonstrate that the level of HIV-1 usRNA in PBMC, measured in cART-treated patients with undetectable plasma viremia, is a strong predictive marker for the outcome of therapy.

Long term outcomes of antiretroviral therapy in a large HIV/AIDS care clinic in urban South Africa: a prospective cohort study

BACKGROUND

Clinical, immunologic and virologic outcomes at large HIV/AIDS care clinics in resource poor settings are poorly described beyond the first year of highly active antiretroviral treatment (HAART). We aimed to prospectively evaluate long-term treatment outcomes at a large scale HIV/AIDS care clinic in South Africa.

METHODS

Cohort study of patients initiating HAART between April 1, 2004 and March 13, 2007, and followed up until April 1, 2008 at a public HIV/AIDS care clinic in Johannesburg, South Africa. We performed time to event analysis on key treatment outcomes and program impact parameters including mortality, retention in care, CD4 count gain, virologic success and first line regimen durability.

RESULTS

7583 HIV-infected patients initiated care and contributed to 161,000 person months follow up. Overall mortality rate was low (2.9 deaths per 100 person years, 95% CI 2.6-3.2), but high in the first three months of HAART (8.4 per 100 person years, 95% CI 7.2-9.9). Long-term on-site retention in care was relatively high (74.4% at 4 years, 95%CI 73.2-75.6). CD4 count was above 200 cells/mm(3 )after 6 months of treatment in almost all patients. By the fourth year of HAART, the majority (59.6%, 95%CI 57.8-61.4) of patients had at least one first line drug (mainly stavudine) substituted. Women were twice as likely to experience drug substitution (OR 1.97, 95% CI 1.80-2.16). By 6 months of HAART, 90.8% suppressed virus below 400 copies. Among those with initial viral suppression, 9.4% (95% CI 8.5-10.3%) had viral rebound within one year of viral suppression, 16.8% (95% CI 15.5-18.1) within 2 years, and 20.6% (95% CI 18.9-22.4) within 3 years of initial suppression. Only 10% of women and 13% of men initiated second line HAART.

CONCLUSION

Despite advanced disease presentation and a very large-scale program, high quality care was achieved as indicated by good long-term clinical, immunologic and virologic outcomes and a low rate of second line HAART initiation. High rates of single drug substitution suggest that the public health approach to HAART could be further improved by the use of a more durable first line regimen.

HIV-1 Protease: Structural Perspectives on Drug Resistance

Antiviral inhibitors of HIV-1 protease are a notable success of structure-based drug design and have dramatically improved AIDS therapy. Analysis of the structures and activities of drug resistant protease variants has revealed novel molecular mechanisms of drug resistance and guided the design of tight-binding inhibitors for resistant variants. The plethora of structures reveals distinct molecular mechanisms associated with resistance: mutations that alter the protease interactions with inhibitors or substrates; mutations that alter dimer stability; and distal mutations that transmit changes to the active site. These insights will inform the continuing design of novel antiviral inhibitors targeting resistant strains of HIV.