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

Substantial decline in heavily treated therapy-experienced persons with HIV with limited antiretroviral treatment options

OBJECTIVE

Historically, a high burden of resistance to antiretroviral therapy (ART) in heavily treatment-experienced (HTE) persons with HIV (PWH) resulted in limited treatment options (LTOs). We evaluated the prevalence, risk factors, and virologic control of HTE PWH with LTO throughout the modern ART era.

DESIGN

We examined all ART-experienced PWH in care between 2000 and 2017 in the Centers for AIDS Research Network of Integrated Clinical Systems cohort.

METHODS

We computed the annual prevalence of HTE PWH with LTO defined as having two or less available classes with two or less active drugs per class based on genotypic data and cumulative antiretroviral resistance. We used multivariable Cox proportional hazards models to examine risk of LTO by 3-year study entry periods adjusting for demographic and clinical characteristics.

RESULTS

Among 27 133 ART-experienced PWH, 916 were classified as having LTO. The prevalence of PWH with LTO was 5.2-7.5% in 2000-2006, decreased to 1.8% in 2007, and remained less than 1% after 2012. Persons entering the study in 2009-2011 had an 80% lower risk of LTO compared with those entering in 2006-2008 (adjusted hazard ratio 0.20; 95% confidence interval: 0.09-0.42). We found a significant increase in undetectable HIV viral loads among PWH ever classified as having LTO from less than 30% in 2001 to more than 80% in 2011, comparable with persons who never had LTO.

CONCLUSION

Results of this large multicenter study show a dramatic decline in the prevalence of PWH with LTO to less than 1% with the availability of more potent drugs and a marked increase in virologic suppression in the current ART era.

Incidence, clinical presentation, and outcome of HIV-1-associated cryptococcal meningitis during the highly active antiretroviral therapy era: a nationwide cohort study

BACKGROUND

Human immunodeficiency virus (HIV) infection with advanced immunosuppression predisposes to cryptococcal meningitis (CM). We describe the incidence, clinical presentation, and outcome of CM in HIV-infected individuals during the highly active antiretroviral therapy (HAART) era.

METHODS

A nationwide, population-based cohort of HIV-infected individuals was used to estimate incidence and mortality of CM including risk factors. A description of neurological symptoms of CM at presentation and follow-up in the study period 1995-2014 was included in this study.

RESULTS

Among 6,351 HIV-infected individuals, 40 were diagnosed with CM. The incidence rates were 3.7, 1.8, and 0.3 per 1000 person-years at risk in 1995-1996, 1997-1999, and 2000-2014, respectively. Initiation of HAART was associated with decreased risk of acquiring CM [incidence rate ratio (IRR), 0.1 (95% CI, 0.05-0.22)]. African origin was associated with increased risk of CM [IRR, 2.05 (95% CI, 1.00-4.20)]. The main signs and symptoms at presentation were headache, cognitive deficits, fever, neck stiffness, nausea, and vomiting. All individuals diagnosed with CM had a CD4⁺ cell count <200 cells/µl [median 26; interquartile range (IQR), 10-50)]. Overall, mortality following CM was high and mortality in the first 4 months has not changed substantially over time. However, individuals who survived generally had a favorable prognosis, with 86% (18/21) returning to the pre-CM level of activity.

CONCLUSION

The incidence of HIV-associated CM has decreased substantially after the introduction of HAART. To further decrease CM incidence and associated mortality, early HIV diagnosis and HAART initiation seems crucial.

Using drug exposure for predicting drug resistance - A data-driven genotypic interpretation tool

Antiretroviral treatment history and past HIV-1 genotypes have been shown to be useful predictors for the success of antiretroviral therapy. However, this information may be unavailable or inaccurate, particularly for patients with multiple treatment lines often attending different clinics. We trained statistical models for predicting drug exposure from current HIV-1 genotype. These models were trained on 63,742 HIV-1 nucleotide sequences derived from patients with known therapeutic history, and on 6,836 genotype-phenotype pairs (GPPs). The mean performance regarding prediction of drug exposure on two test sets was 0.78 and 0.76 (ROC-AUC), respectively. The mean correlation to phenotypic resistance in GPPs was 0.51 (PhenoSense) and 0.46 (Antivirogram). Performance on prediction of therapy-success on two test sets based on genetic susceptibility scores was 0.71 and 0.63 (ROC-AUC), respectively. Compared to geno2pheno_[resistance], our novel models display a similar or superior performance. Our models are freely available on the internet via www.geno2pheno.org. They can be used for inferring which drug compounds have previously been used by an HIV-1-infected patient, for predicting drug resistance, and for selecting an optimal antiretroviral therapy. Our data-driven models can be periodically retrained without expert intervention as clinical HIV-1 databases are updated and therefore reduce our dependency on hard-to-obtain GPPs.

Impact of peer support on virologic failure in HIV-infected patients on antiretroviral therapy - a cluster randomized controlled trial in Vietnam

Background

The effect of peer support on virologic and immunologic treatment outcomes among HIVinfected patients receiving antiretroviral therapy (ART) was assessed in a cluster randomized controlled trial in Vietnam.

Methods

Seventy-one clusters (communes) were randomized in intervention or control, and a total of 640 patients initiating ART were enrolled. The intervention group received peer support with weekly home-visits. Both groups received first-line ART regimens according to the National Treatment Guidelines. Viral load (VL) (ExaVir™ Load) and CD4 counts were analyzed every 6 months. The primary endpoint was virologic failure (VL >1000 copies/ml). Patients were followed up for 24 months. Intention-to-treat analysis was used. Cluster longitudinal and survival analyses were used to study time to virologic failure and CD4 trends.

Results

Of 640 patients, 71% were males, mean age 32 years, 83% started with stavudine/lamivudine/nevirapine regimen. After a mean of 20.8 months, 78% completed the study, and the median CD4 increase was 286 cells/μl. Cumulative virologic failure risk was 7.2%. There was no significant difference between intervention and control groups in risk for and time to virologic failure and in CD4 trends. Risk factors for virologic failure were ART-non-naïve status [aHR 6.9;(95% CI 3.2–14.6); p < 0.01]; baseline VL ≥100,000 copies/ml [aHR 2.3;(95% CI 1.2–4.3); p < 0.05] and incomplete adherence (self-reported missing more than one dose during 24 months) [aHR 3.1;(95% CI 1.1–8.9); p < 0.05]. Risk factors associated with slower increase of CD4 counts were: baseline VL ≥100,000 copies/ml [adj.sq.Coeff (95% CI): −0.9 (−1.5;−0.3); p < 0.01] and baseline CD4 count <100 cells/μl [adj.sq.Coeff (95% CI): −5.7 (−6.3;−5.4); p < 0.01]. Having an HIV-infected family member was also significantly associated with gain in CD4 counts [adj.sq.Coeff (95% CI): 1.3 (0.8;1.9); p < 0.01].

Conclusion

There was a low virologic failure risk during the first 2 years of ART follow-up in a rural low-income setting in Vietnam. Peer support did not show any impact on virologic and immunologic outcomes after 2 years of follow up.

Trial registration

NCT01433601.

Smoking and renal function in people living with human immunodeficiency virus: a Danish nationwide cohort study

INTRODUCTION

Smoking is a main risk factor for morbidity and mortality in people living with human immunodeficiency virus (PLHIV), but its potential association with renal impairment remains to be established.

METHODS

We did a nationwide population-based cohort study in Danish PLHIV to evaluate the association between smoking status and 1) overall renal function and risk of chronic kidney disease (CKD), 2) risk of any renal replacement therapy (aRRT), and 3) mortality following aRRT. We calculated estimated creatinine clearance using the Cockcroft-Gault equation (CG-CrCl), and evaluated renal function graphically. We calculated cumulative incidence of CKD (defined as two consecutive CG-CrCls of ≤60 mL/min, ≥3 months apart) and aRRT and used Cox regression models to calculate incidence rate ratios (IRRs) for risk of CKD, aRRT, and mortality rate ratios (MRRs) following aRRT.

RESULTS

From the Danish HIV Cohort Study, we identified 1,475 never smokers, 768 previous smokers, and 2,272 current smokers. During study period, we observed no association of smoking status with overall renal function. Previous and current smoking was not associated with increased risk of CKD (adjusted IRR: 1.1, 95% confidence interval [CI]: 0.7-1.7; adjusted IRR: 1.3, 95% CI: 0.9-1.8) or aRRT (adjusted IRR: 0.8, 95% CI: 0.4-1.7; adjusted IRR: 0.9, 95% CI: 0.5-1.7). Mortality following aRRT was high in PLHIV and increased in smokers vs never smokers (adjusted MRR: 3.8, 95% CI: 1.3-11.2).

CONCLUSION

In Danish PLHIV, we observed no strong association between smoking status and renal function, risk of CKD, or risk of aRRT, but mortality was increased in smokers following aRRT.

Treatment Modifications and Treatment-Limiting Toxicities or Side Effects: Risk Factors and Temporal Trends

Combined antiretroviral treatment (cART) modifications are often required due to treatment failure or side effects. We investigate cART regimens' durability, frequency of treatment-limiting adverse events, and potential risk factors and temporal trends. Data were derived from the Athens Multicenter AIDS Cohort Study (AMACS). Statistical analyses were based on survival techniques, allowing for multiple contributions per individual. Overall, 2,756 individuals, aged >15 years, initiated cART. cART regimens were grouped by their initiation date into four calendar periods (1995-1998, 1999-2002, 2003-2006, and 2007+). Median [95% confidence interval (CI)] time to first treatment modification was 2.11 (1.95-2.33) years; cumulative probabilities at 1 year were 31.6%, 29.0%, 33.1%, and 29.6% for the four periods, respectively. cART modifications were less frequent in more recent years (adjusted HR=0.96 per year; p<0.001). Longer treatment duration was associated with lower HIV-RNA, higher CD4 counts, and being previously ART naive. cART modifications due to treatment failure became less frequent in recent years (adjusted HR=0.91 per year; p<0.001). Estimated (95% CI) 1 year cumulative probabilities of treatment-limiting side effects were 16.4% (12.0-21.3%), 19.3% (15.6-23.3%), 24.9% (20.3-29.7%), and 21.1% (13.4-29.9%) for the four periods, respectively, with no significant temporal trends. Risk of side effects was lower in nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens or triple nucleoside reverse transcriptase inhibitor (NRTI)-based cART regimens. Treatment modifications have become less frequent in more recent years. This could be partly attributed to the lower risk for side effects of NNRTI-based cART regimens and mainly to the improved efficacy of newer drugs. However, the rate of drugs substitutions due to adverse events remains substantially high.

Poor CD4 response despite viral suppression is associated with increased non-AIDS-related mortality among HIV patients and their parents

INTRODUCTION

Poor CD4 response to antiretroviral treatment (HAART) is associated with increased mortality. We analyzed the impact of CD4 increase on non-AIDS-related morbidity and on mortality in HIV patients and their parents.

METHODS

Mortality rates were estimated among 1758 virally suppressed patients in the Danish HIV Cohort Study after 2 years on HAART and among their parents (n = 1603). Analyses were stratified by pre-HAART CD4 count and CD4 increase. Incidence rate ratios (IRRs) of non-AIDS-related morbidity and mortality rate ratios (MRR) were analyzed using Poisson regression.

RESULTS

CD4 increases less than 25 vs. more than 100 cells/μl was associated with increased mortality [MRR 3.5 (95% confidence interval (CI) 1.8-6.8)] even in individuals with pre-HAART CD4 cell count more than 250 cells/μl (MRR 3.2 (95%CI, 1.3-7.8). Mortality of parents of patients with poor CD4 response was also increased [MRR 1.5 (95%CI, 1.1-2.1)]. There was a trend towards association between poor CD4 response and increased risk of cardiovascular disease and cancer [IRR 1.6 (95%CI, 0.8-3.2) and 1.6 (95%CI, 0.6-4.8)].

CONCLUSION

Poor CD4 increase post-HAART is associated with adverse prognosis even in absence of severe immunosuppression. CD4 response in HIV patients is associated with mortality among their parents, thus poor CD4 response may be caused by genetic factors, which might also affect morbidity and mortality in the HIV-negative population.

Mortality attributable to smoking among HIV-1-infected individuals: a nationwide, population-based cohort study

BACKGROUND

We assessed mortality attributable to smoking among patients with human immunodeficiency virus (HIV).

METHODS

We estimated mortality rates (MRs), mortality rate ratios (MRRs), life expectancies, life-years lost, and population-attributable risk of death associated with smoking and with HIV among current and nonsmoking individuals from a population-based, nationwide HIV cohort and a cohort of matched HIV-negative individuals.

RESULTS

A total of 2921 HIV patients and 10 642 controls were followed for 14 281 and 45 122 person-years, respectively. All-cause and non-AIDS-related mortality was substantially increased among smoking compared to nonsmoking HIV patients (MRR, 4.4 [95% confidence interval {CI}, 3.0-6.7] and 5.3 [95% CI, 3.2-8.8], respectively). Excess MR per 1000 person-years among current vs nonsmokers was 17.6 (95% CI, 13.3-21.9) for HIV patients and 4.8 (95% CI, 3.2-6.4) for controls. A 35-year-old HIV patient had a median life expectancy of 62.6 years (95% CI, 59.9-64.6) for smokers and 78.4 years (95% CI, 70.8-84.0) for nonsmokers; the numbers of life-years lost in association with smoking and HIV were 12.3 (95% CI, 8.1-16.4) and 5.1 (95% CI, 1.6-8.5). The population-attributable risk of death associated with smoking was 61.5% among HIV patients and 34.2% among controls.

CONCLUSIONS

In a setting where HIV care is well organized and antiretroviral therapy is free of charge, HIV-infected smokers lose more life-years to smoking than to HIV. The excess mortality of smokers is tripled and the population-attributable risk of death associated with smoking is doubled among HIV patients compared to the background population.

Predictors of CD4(+) T-cell counts of HIV type 1-infected persons after virologic failure of all 3 original antiretroviral drug classes

BACKGROUND

Low CD4(+) T-cell counts are the main factor leading to clinical progression in human immunodeficiency virus type 1 (HIV-1) infection. We aimed to investigate factors affecting CD4(+) T-cell counts after triple-class virological failure.

METHODS

We included individuals from the COHERE database who started antiretroviral therapy from 1998 onward and who experienced triple-class virological failure. CD4(+) T-cell counts obtained after triple-class virologic failure were analyzed using generalized estimating equations.

RESULTS

The analyses included 2424 individuals with a total of 23 922 CD4(+) T-cell count measurements. In adjusted models (excluding current viral load and year), CD4(+) T-cell counts were higher with regimens that included boosted protease inhibitors (increase, 22 cells/µL [95% confidence interval {CI}, 3.9-41]; P = .017) or drugs from the new classes (increase, 39 cells/µL [95% CI, 15-62]; P = .001), compared with nonnucleoside reverse-transcriptase inhibitor-based regimens. These associations disappeared when current viral load and/or calendar year were included. Compared with viral levels of <2.5 log(10) copies/mL, levels of 2.5-3.5, 3.5-4.5, 4.5-5.5, and >5.5 log(10) copies/mL were associated with CD4(+) T-cell count decreases of 51, 84, 137, and 186 cells/µL, respectively (P < .001).

CONCLUSIONS

The approximately linear inverse relationship between log(10) viral load and CD4(+) T-cell count indicates that there are likely immunologic benefits from lowering viral load even by modest amounts that do not lead to undetectable viral loads. This is important for patients with low CD4(+) T-cell counts and few drug options.

Decreasing rate of multiple treatment modifications among individuals who initiated antiretroviral therapy in 1997-2009 in the Danish HIV Cohort Study

BACKGROUND

We hypothesized that rates and reasons for treatment modifications have changed since the implementation of combination antiretroviral therapy (cART) due to improvements in therapy.

METHODS

From a nationwide population-based cohort study we identified all HIV-1-infected adults who initiated cART in Denmark 1997-2009 and were followed ≥1 year. Incidence rate ratios (IRRs) and reasons for treatment modifications were estimated and compared between patients, who initiated treatment in 1997-1999, 2000-2004 and 2005-2009. Rates of discontinuation of individual antiretroviral drugs (ARVs) were evaluated.

RESULTS

A total of 3,107 patients were followed for a median of 7.3 years (IQR 3.8-10.8). Rates of first treatment modification ≤1 year after cART initiation did not change (IRR 0.88 [95% CI 0.78, 1.01] and 1.03 [95% CI 0.90, 1.18] in 2000-2004 and 2005-2009, respectively, compared with 1997-1999). Rates of multiple modifications decreased markedly (2000-2004 IRR 0.60 [95% CI 0.53, 0.67] and 2005-2009 IRR 0.38 [95% CI 0.32, 0.46]). Rates of treatment modifications due to virological failure, toxicity and other/unknown reasons decreased (IRR 0.25 [95% CI 0.14, 0.45], 0.69 [95% CI 0.56, 0.83] and 0.45 [95% CI 0.36, 0.57], respectively, in 2005-2009 compared with 1997-1999), whereas the rate of modifications with the aim of simplification increased (IRR 1.85 [95% CI 1.52, 2.25]).

CONCLUSIONS

Rates of first treatment modification ≤1 year after cART initiation have not changed since the early cART era, whereas the risk of multiple modifications has decreased markedly. Modifications due to virological failure and toxicity have decreased substantially, whereas rates of switch to simpler and less toxic regimens have increased.

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.

Resistance evolution in HIV - modeling when to intervene

The treatment of HIV is complicated by the evolution of antiviral drug resistant virus and the limited availability of antigenically independent antiviral regimens. The consequences to the patient of successive virological failures is such that many strategies to minimize the occurrence of such failures are being investigated. In this paper, a Markov chain-based model of virological failure is introduced. This model considers sequential failure events, and differentiates between several modes of virological failure. This model is then used to evaluate the resistance- targeted interventions by means of testing the impact of a viral load preconditioning strategy on total treatment regimen longevity in HIV patients. It is shown that a proposed intervention targeting pre-existing resistance has the potential to increase the expected time to three sequential virological failures by an average of 3.3 years per patient. When combined with an intervention targeting patient compliance, the total potential increase in the time to three sequential virological failures is as high as 11.2 years. The impact on patient and public health is discussed.

Adherence to national guidelines for initiation of antiretroviral regimens in HIV patients: a Danish nationwide study

AIM

To determine the adherence to the national guidelines for start of highly active antiretroviral treatment (HAART) in HIV infected patients.

METHODS

We used a Danish nationwide cohort of HIV infected patients to calculate the fraction of patients who in the period 1997-2006 started HAART according to the guidelines from The Danish Society of Infectious Diseases. We used Kaplan-Meier tables to estimate time from fulfilling the criteria for start of HAART to initiation of the treatment. Cox regression and logistic regression was used to identify risk factors for delayed initiation of treatment and chance of being included in clinical trials.

RESULTS

The study included 3223 patients, 74% of whom initiated HAART in the study period. Ninety-four% fulfilled the criteria for start of HAART, with minor differences over calendar periods. Ninety-four% initiated a recommended regimen or were included in a clinical trial. Intravenous drug use predicted initiation of a non-recommended regimen and delay in start of HAART, while non-Caucasians were less likely to be included in clinical trials.

CONCLUSIONS

In a Western world setting, the adherence to national guidelines for start of HAART can be high. We suggest that simplicity of the guidelines, centralization of treatment and involvement of local clinicians in the development of guidelines are of major importance for high adherence to treatment guidelines.

Molecular phylogenetics of transmitted drug resistance in newly diagnosed HIV Type 1 individuals in Denmark: a nation-wide study

Highly active antiretroviral treatment is compromised by viral resistance mutations. Transmitted drug resistance (TDR) is therefore monitored closely, but follow-up studies of these patients are limited. Virus from 1405 individuals diagnosed with HIV-1 in Denmark between 2001 and 2009 was analyzed for TDR, and molecular-epidemiological links and progression of the infection were described based on data from standardized questionnaires, the prospective Danish HIV Cohort Study, and by phylogenetic analysis. Eighty-five individuals were found to be infected with virus harboring mutations resulting in a prevalence of 6.1%, with no changes over time. The main resistance mutations were nucleoside reverse transcriptase inhibitor (NRTI) mutation 215 revertants, as well as nonnucleoside reverse transcriptase inhibitor (NNRTI) mutation 103N/S and protease inhibitor (PI) mutations 90M and 85V. Phylogenetic analysis confirmed 12 transmission chains involving 37 TDR individuals. Of these 21 were also documented epidemiologically. The virus included in the transmission chain carried similar resistance mutations to the TDR index case, whereas controls chains from index cases without TDR were generally without resistance mutations. We observed no difference in progression of the infection between individuals infected with TDR and individuals infected with wild-type HIV-1. The prevalence of TDR is low in Denmark and transmission of dual-drug-resistant HIV-1 is infrequent. The TDR isolates were shown to originate from local patients failing therapy.

Triple class experience after initiation of combination antiretroviral treatment in Australia: survival and projections

BACKGROUND

Patients who have become triple class experienced (TCE) are at a high risk of exhausting available treatment options. This study aims to investigate factors associated with becoming TCE and to explore the effect of becoming TCE on survival. We also project the prevalence of TCE in Australia to 2012.

METHODS

Patients were defined as TCE when they stopped a combination antiretroviral treatment (cART) that introduced the third of the three major antiretroviral classes. Cox proportional hazards models were used to investigate factors associated with TCE and the effect of TCE on survival. To project TCE prevalence, we used predicted rates of TCE by fitting a Poisson regression model, together with the estimated number of patients who started cART in each year in Australia, assuming a mortality rate of 1.5 per 100 person-years.

RESULTS

Of the 1498 eligible patients, 526 became TCE. Independent predictors of a higher risk of TCE included current CD4 counts below 200cellsμL(-1) and earlier calendar periods. No significant difference in survival was observed between those who were TCE and those who were not yet TCE. An increasing number of patients are using cART in Australia and if current trends continue, the number of patients who are TCE is estimated to increase from 2800 in 2003 to 5000 in 2012.

CONCLUSION

Our results suggest that the prevalence of TCE in Australia is estimated to plateau after 2003. However, as an increasing number of patients are becoming TCE, it is necessary to develop new drugs that come from new classes or do not have overlapping resistance.

Missing data on the estimation of the prevalence of accumulated human immunodeficiency virus drug resistance in patients treated with antiretroviral drugs in north america

Determination of the prevalence of accumulated antiretroviral drug resistance among persons infected with human immunodeficiency virus (HIV) is complicated by the lack of routine measurement in clinical care. By using data from 8 clinic-based cohorts from the North American AIDS Cohort Collaboration on Research and Design, drug-resistance mutations from those with genotype tests were determined and scored using the Genotypic Resistance Interpretation Algorithm developed at Stanford University. For each year from 2000 through 2005, the prevalence was calculated using data from the tested subset, assumptions that incorporated clinical knowledge, and multiple imputation methods to yield a complete data set. A total of 9,289 patients contributed data to the analysis; 3,959 had at least 1 viral load above 1,000 copies/mL, of whom 2,962 (75%) had undergone at least 1 genotype test. Using these methods, the authors estimated that the prevalence of accumulated resistance to 2 or more antiretroviral drug classes had increased from 14% in 2000 to 17% in 2005 (P < 0.001). In contrast, the prevalence of resistance in the tested subset declined from 57% to 36% for 2 or more classes. The authors' use of clinical knowledge and multiple imputation methods revealed trends in HIV drug resistance among patients in care that were markedly different from those observed using only data from patients who had undergone genotype tests.

Bone mineral density changes in protease inhibitor-sparing vs. nucleoside reverse transcriptase inhibitor-sparing highly active antiretroviral therapy: data from a randomized trial

OBJECTIVE

The aim of the study was to compare changes in bone mineral density (BMD) over 144 weeks in HIV-infected patients initiating nucleoside reverse transcriptase inhibitor (NRTI)-sparing or protease inhibitor-sparing highly active antiretroviral therapy (HAART).

METHODS

Sixty-three HAART-naïve patients were randomized to zidovudine/lamivudine+efavirenz or lopinavir/ritonavir+efavirenz. We performed dual energy X-ray absorptiometry (DEXA) at baseline and at weeks 24, 48, 96 and 144 to evaluate lumbar spine and femoral neck (hip) BMD.

RESULTS

At baseline, 33 patients (55.9%) had low BMD (T-score < -1.0) and of these eight had osteoporosis (T-score < -2.5). Spine BMD declined in both arms until week 24, before stabilizing. In the NRTI-sparing arm, the mean percentage change from baseline was -2.7% [95% confidence interval (CI) -3.9 to -1.4] at week 24 and -2.5% (95% CI -5.4 to 0.3) at week 144, compared with -3.2% (95% CI -4.4 to -2.1) and -1.9% (95% CI -3.5 to -0.3) in the protease inhibitor-sparing arm. Hip BMD declined until week 48 before stabilizing. In the NRTI-sparing arm, BMD had decreased by -5.1% (95% CI -7.1 to -3.1) at week 48 and -4.5% (95% CI -6.9 to -2.1) at week 144, compared with -6.1% (95% CI -8.2 to -4.0) and -5.0% (95% CI -6.8 to -3.1) in the protease inhibitor-sparing arm. There were no significant differences between arms. Low baseline CD4 cell count was independently associated with spine (P=0.007) and hip (P=0.04) BMD loss and low body mass index with hip BMD loss (P=0.03).

CONCLUSION

Spine and hip BMD declined rapidly 24 to 48 weeks after initiating HAART, independent of the assigned drug class, but thereafter BMD values remained stable.

Clinical, virological and immunological responses in Danish HIV patients receiving raltegravir as part of a salvage regimen

BACKGROUND

Raltegravir is the first integrase inhibitor approved for treatment of HIV-infected patients harboring multiresistant viruses.

METHODS

From a Danish population-based nationwide cohort of HIV patients we identified the individuals who initiated a salvage regimen including raltegravir and a matched cohort of HIV-infected patients initiating HAART for the first time. We compared these two cohorts for virological suppression, gain in CD4 count, and time to first change of initial regimen.

RESULTS

We identified 32 raltegravir patients and 64 HIV patients who initiated HAART for the first time in the period 1 January 2006 to 1 July 2009. The virological and immunological responses in the raltegravir patients were comparable to those seen in the control cohort. No patients in the two cohorts died and no patients terminated raltegravir treatment in the observation period. Time to first change of initial regimen was considerably shorter for HAART-naïve patients.

CONCLUSION

We conclude that salvage regimens including raltegravir have high effectiveness in the everyday clinical setting. The effectiveness of the regimens is comparable to that observed for patients initiating HAART for the first time. The risk of change in the salvage regimens after initiation of raltegravir is low.

Triple-class virologic failure in HIV-infected patients undergoing antiretroviral therapy for up to 10 years

BACKGROUND

Life expectancy of people with human immunodeficiency virus (HIV) is now estimated to approach that of the general population in some successfully treated subgroups. However, to attain these life expectancies, viral suppression must be maintained for decades.

METHODS

We studied the rate of triple-class virologic failure (TCVF) in patients within the Collaboration of Observational HIV Epidemiological Research Europe (COHERE) who started antiretroviral therapy (ART) that included a nonnucleoside reverse-transcriptase inhibitor (NNRTI) or a ritonavir-boosted protease inhibitor (PI/r) from 1998 onwards. We also focused on TCVF in patients who started a PI/r-containing regimen after a first-line NNRTI-containing regimen failed.

RESULTS

Of 45 937 patients followed up for a median (interquartile range) of 3.0 (1.5-5.0) years, 980 developed TCVF (2.1%). By 5 and 9 years after starting ART, an estimated 3.4% (95% confidence interval [CI], 3.1%-3.6%) and 8.6% (95% CI, 7.5%-9.8%) of patients, respectively, had developed TCVF. The incidence of TCVF rose during the first 3 to 4 years on ART but plateaued thereafter. There was no significant difference in the risk of TCVF according to whether the initial regimen was NNRTI or PI/r based (P = .11). By 5 years after starting a PI/r regimen as second-line therapy, 46% of patients had developed TCVF.

CONCLUSIONS

The rate of virologic failure of the 3 original drug classes is low, but not negligible, and does not appear to diminish over time from starting ART. If this trend continues, many patients are likely to need newer drugs to maintain viral suppression. The rate of TCVF from the start of a PI/r regimen after NNRTI failure provides a comparator for studies of response to second-line regimens in resource-limited settings.

Sustained low-dose growth hormone therapy optimizes bioactive insulin-like growth factor-I level and may enhance CD4 T-cell number in HIV infection

High-dose recombinant human growth hormone (rhGH) (2-6 mg/day) regimes may facilitate T-cell restoration in patients infected with human immunodeficiency virus (HIV) on highly active antiretroviral therapy (HAART). However, high-dose rhGH regimens increase insulin-like growth factor-I (IGF-I) to supra-physiological levels associated with severe side effects. The present study investigated whether lower doses of rhGH may improve T-cell restoration in patients infected with HIV following an expedient response of total and bioactive (i.e., free) IGF-I. A previous 16-week pilot-study included six HIV-infected patients on stable HAART to receive rhGH 0.7 mg/day, which increased total (+117%, P < 0.01) and free (+155%, P < 0.01) IGF-I levels. The study was extended to examine whether continuous use of low-dose rhGH (0.7 mg/day until week 60; 0.4 mg/day from week 60 to week 140) would maintain expedient IGF-I levels and improve CD4 T-cell response. Total and free IGF-I increased at week 36 (+97%, P < 0.01 and +125%, P < 0.01, respectively) and week 60 (+77%, P = 0.01 and +125%, P < 0.01) compared to baseline levels (161 +/- 15 and 0.75 +/- 0.11 microg/L). CD4 T-cell number increased at week 36 (+15%, P < 0.05) and week 60 (+31%, P = 0.01) compared to baseline levels (456 +/- 55 cells/microL). Following rhGH dose reduction, total IGF-I and CD4 T-cell number remained increased at week 88 (+44%, P = 0.01 and +33%, P < 0.01) and week 140 (+46%, P = 0.07 and +36%, P = 0.02) compared to baseline levels. These data support the notion that low-dose rhGH regimens may increase expediently total and bioactive IGF-I and improve T-cell restoration in patients infected with HIV on HAART.

Risk of high-level viraemia in HIV-infected patients on successful antiretroviral treatment for more than 6 months

OBJECTIVES

According to the Swiss Federal Commission for HIV/AIDS, HIV-infected patients on successful antiretroviral treatment have a negligible risk of transmitting HIV sexually. We estimated the risk that patients considered to have an undetectable viral load (VL) are actually viraemic.

METHODS

A Danish, population-based nationwide cohort study of HIV-infected patients with VL <51 HIV-1 RNA copies/mL for more than 6 months was carried out for the study period 2000-2008. The observation time was calculated from 6 months after the first VL <51 copies/mL to the last measurement of VL or the first VL >50 copies/mL. The time at risk of transmitting HIV sexually was calculated as 50% of the time from the last VL <51 copies/mL to the subsequent VL if it was >1000 copies/mL. The outcome was the time at risk of transmitting HIV sexually divided by the observation time.

RESULTS

We identified 2680 study subjects contributing 9347.7 years of observation time and 56.4 years of risk of transmitting HIV (VL>1000 copies/mL). In 0.6% [95% confidence interval (CI) 0.5-0.8%] of the overall observation time the patients had VL >1000 copies/mL. In the first 6 months this risk was substantially higher (7.9%; 95% CI 4.5-11.0%), but thereafter decreased and was almost negligible after 5 years (0.03%; 95% CI 0.0-0.2%). The risk was higher in injecting drug users, but otherwise did not differ between subgroups of patients.

CONCLUSION

The risk of viraemia and therefore the risk of transmitting HIV sexually are high in the first 12 months of successful antiretroviral treatment, but thereafter are low.

Trends over calendar time in antiretroviral treatment success and failure in HIV clinic populations

OBJECTIVE

Effective antiretroviral therapy (ART) has transformed the care of people with HIV, but it is important to monitor time trends in indicators of treatment success and antic future changes.

METHODS

We assessed time trends from 2000 to 2007 in several indicators of treatment success in the UK Collaborative HIV Cohort (CHIC) Study, and using national HIV data from the Health Protection Agency (HPA) we developed a model to project future trends.

RESULTS

The proportion of patients on ART with a viral load <50 HIV-1 RNA copies/mL increased from 62% in 2000 to 84% in 2007, and the proportion of all patients with a CD4 count <200 cells/microL decreased from 21% to 10%. During this period, the number of patients who experienced extensive triple class failure (ETCF) rose from 147 (0.9%) to 1771 (3.9%). The number who experienced such ETCF and had a current viral load >50 copies/mL rose fromz 118 (0.7%) to 857 (1.9%). Projections to 2012 suggest sustained high levels of success, with a continued increase in the number of patients who have failed multiple drugs but a relatively stable number of such patients experiencing viral loads >50 copies/mL. Numbers of deaths are projected to remain low.

CONCLUSIONS

There have been continued improvements in key indicators of success in patients with HIV from 2000 to 2007. Although the number of patients who have ETCF is projected to rise in the future, the number of such patients with viral loads >50 copies/mL is not projected to increase up to 2012. New drugs may be needed in future to sustain these positive trends.

Triple-class HIV antiretroviral therapy failure in an Australian primary care setting

Objective: To determine the prevalence, characteristics and virological outcomes of triple-class antiretroviral drug failure (TCF) and triple-class virological failure (TCVF) in HIV-infected patients attending an Australian high caseload primary care clinic. Methods: Cross-sectional observational study using a retrospective review of electronic medical records from 1007 patients with HIV attending Holdsworth House Medical Practice in Darlinghurst, Australia, between 2007 and 2008. TCF was defined as failure (virological, immunological, clinical, intolerance or other) of at least one drug in each of the three major classes of highly active antiretroviral therapy. Results: A total of 51 patients (5.1%) with TCF were identified. Of these patients, 31.4% had experienced virological failure of each of the three main drug classes. Eighty-eight percent of patients with TCF and 75% of patients with TCVF had achieved virological suppression (HIV RNA <400 copies mL–1). Total mean (s.d.) duration on antiretroviral therapy (ART) was 12.2 (3.3) years, with patients receiving an average of 18 antiretroviral drugs during this period. Reasons for treatment change included intolerance (88% of patients), virological failure (84%), immunological failure (24%) and poor adherence (20%). Conclusions: The prevalence of TCF and TCVF in patients with long-term HIV infection and extensive antiretroviral experience is low in primary care sites. Despite experiencing failure to the three main classes of ART, successful virological outcomes are still achievable in the majority of such patients.

Improvements in antiretroviral therapy outcomes over calendar time

PURPOSE OF REVIEW

The introduction of combination antiretroviral therapy (cART) led to substantial reductions in HIV-associated morbidity and mortality. However, the regimens in the early cART era were cumbersome and toxic. The introduction of new ART agents, fixed-dose combinations and novel strategies for cART delivery such as ritonavir 'boosting' of HIV-protease inhibitors have led to a perception of improvements in the tolerability and durability of contemporary cART regimens. It is in turn assumed that these developments have led to improved outcomes in the latter era of cART.

RECENT FINDINGS

Both cohort studies and randomized clinical trials suggest improvements in cART outcomes over calendar time. Key associated factors include reduced pill burden and dosing interval and improved tolerability and reduced toxicity of newer ART. A critical appreciation of the association between ART adherence and regimen durability has been important. Cohorts in recent times have included more patients who are completely ART-naïve at therapy initiation.

SUMMARY

The prognosis of HIV infection in developed countries is in the order of 40 years after cART initiation. An appreciation of the factors associated with long-term control of HIV viraemia is essential for the optimal management of the HIV-infected individual in contemporary practice.

Immunological responses during a virologically failing antiretroviral regimen are associated with in vivo synonymous mutation rates of HIV type-1 env

Background

Little is known about the underlying causes of differences in immunological response to antiretroviral therapy during multidrug-resistant (MDR) HIV type-1 (HIV-1) infection. This study aimed to identify virological factors associated with immunological response during therapy failure.

Methods

Individuals with MDR HIV-1 receiving therapy for ≥3 months were included. CD4+ T-cell count slopes and pol and clonal env sequences were determined. Genetic analyses were performed using distance-based and maximum likelihood methods. Synonymous mutations rates of env were used to estimate viral replication.

Results

Of 1,000 patients treated between 1995 and 2003, 72 individuals fulfilled the definition for triple-class failure, but 25 were non-compliant, 21 were successfully resuppressed and 3 had died or quit therapy. Of the 23 that fulfilled study criteria, 16 had samples available for analysis. In a longitudinal mixed-effects model, plasma HIV-1 RNA only tended to predict immunological response ( P=0.06), whereas minor protease inhibitor (PI) and nucleoside reverse transcriptase (NRTI) mutations at baseline correlated significantly with CD4+ T-cell count slopes ( r=-0.56, P=0.04 and r=-0.64, P=0.008, respectively). Interestingly, synonymous mutations of env correlated inversely with CD4+ T-cell count slopes ( r=-0.60; P=0.01) and individuals with codons under positive selection had significantly better CD4+ T-cell responses than individuals without (0.42 versus -5.34; P=0.02).

Conclusions

Our results suggest that minor PI mutations and NRTI mutations present early during therapy failure are predictive of the CD4+ T-cell count slopes. Synonymous mutation rates of the env gene suggested that underlying differences in fitness could cause this association.

Incidence, clinical presentation, and outcome of progressive multifocal leukoencephalopathy in HIV-infected patients during the highly active antiretroviral therapy era: a nationwide cohort study

BACKGROUND

Human immunodeficiency virus (HIV) infection predisposes to progressive multifocal leukoencephalopathy (PML). Here, we describe the incidence, presentation, and prognosis of PML in HIV-1-infected patients during the period before highly active antiretroviral therapy (HAART) (1995-1996) and during the early HAART (1997-1999) and late HAART (2000-2006) periods.

METHODS

Patients from a nationwide population-based cohort of adult HIV-1-infected individuals were included. We calculated incidence rates of PML and median survival times after diagnosis. We also described neurological symptoms at presentation and follow-up.

RESULTS

Among 4,649 patients, we identified 47 patients with PML. The incidence rates were 3.3, 1.8, and 1.3 cases per 1000 person-years at risk in 1995-1996, 1997-1999, and 2000-2006, respectively. The risk of PML was significantly associated with low CD4(+) cell count, and 47% of cases were diagnosed by means of brain biopsy or polymerase chain reaction analysis for JC virus. The predominant neurological symptoms at presentation were coordination disturbance, cognitive defects, and limb paresis. Thirty-five patients died; the median survival time was 0.4 years (95% confidence interval [CI], 0.0-0.7) in 1995-1996 and 1.8 years (95% CI, 0.6-3.0) in both 1997-1999 and 2000-2006. CD4(+) cell count >50 cells/microL at diagnosis of PML was significantly associated with reduced mortality.

CONCLUSIONS

The incidence of PML in HIV-infected patients decreased after the introduction of HAART. Survival after PML remains poor. In the management of PML, the main focus should be on prophylactic measures to avoid immunodeficiency.

Canadian Consensus Recommendations for the Optimal Use of Enfuvirtide in HIV/AIDS Patients

BACKGROUND AND OBJECTIVES

An eight-member group consisting of Canadian infectious disease and immunology specialists and a family physician with significant experience in HIV management was convened to update existing recommendations, specifically intended for use by Canadian HIV-treating physicians, on the appropriate use of enfuvirtide in HIV/AIDS patients with resistance to other antiretroviral drugs.

METHODS

Evidence from the literature and expert opinions of the group members formed the basis of the guidelines. Comments on the draft guidelines were obtained from other physicians across Canada with HIV expertise. The final guidelines represent the group's consensus agreement.

RESULTS AND CONCLUSIONS

The recommendations were developed to guide physicians in optimal practices in patient selection for enfuvirtide treatment and subsequent patient management. The issues considered include positive predictors of response to enfuvirtide, stage of disease, optimization of the background regimen, early indicators of enfuvirtide response, and patient education and support.

Risk of extensive virological failure to the three original antiretroviral drug classes over long-term follow-up from the start of therapy in patients with HIV infection: an observational cohort study

BACKGROUND

The long-term durability of viral-load suppression provided by the three original antiretroviral drugs is not well characterised. We estimated the proportion of patients who had extensive triple-class failure during long-term follow-up and examined characteristics associated with an increased rate of failure.

METHODS

7916 patients who started antiretroviral therapy with three or more drugs were followed up from the time that therapy started until the last viral-load measure. Extensive triple-class virological failure was defined by failure of three subclasses of nucleoside reverse transcriptase inhibitors, a non-nucleoside reverse transcriptase inhibitor, and a ritonavir-boosted protease inhibitor.

FINDINGS

167 patients developed extensive triple-class failure during 27 441 person-years of follow-up. The Kaplan-Meier estimate for the cumulative risk of extensive triple-class failure was 9.2% by 10 years (95% CI 5.0-13.4). There was evidence that this rate has decreased over time (adjusted hazard ratio 0.86 [0.77-0.96] per year more recent; p=0.006). Of the 167 patients with extensive triple-class failure, 101 (60%) subsequently had at least one viral load less than 50 copies per mL. The risk of death by 5 years from the time of extensive triple-class failure was 10.6% (2.4-18.8, nine deaths).

INTERPRETATION

We have shown that extensive virological failure of the three main classes of drugs occurs slowly in routine clinical practice. This finding has implications for the planning of treatment programmes in developing countries, where additional drugs outside these classes are unlikely to be available for some time.

Genotypic Drug Resistance and Long-Term Mortality in Patients with Triple-Class Antiretroviral Drug Failure

Objective

To examine the prevalence of drug-resistance-associated mutations in HIV patients with triple-drug class virological failure (TCF) and their association with long-term mortality.

Design

Population-based study from the Danish HIV Cohort Study (DHCS).

Methods

We included all patients in the DHCS who experienced TCF between January 1995 and November 2004, and we performed genotypic resistance tests for International AIDS Society (IAS)-USA primary mutations on virus from plasma samples taken around the date of TCF. We computed time to all-cause death from date of TCF. The relative risk of death according to the number of mutations and individual mutations was estimated by Cox regression analysis and adjusted for potential confounders.

Results

Resistance tests were done for 133 of the 179 patients who experienced TCF. The median number of resistance mutations was eight (interquartile range 2–10), and 81 (61%) patients had mutations conferring resistance towards all three major drug classes. In a regression model adjusted for CD4+ T-cell count, HIV RNA, year of TCF, age, gender and previous inferior antiretroviral therapy, harbouring ≥9 versus ≤8 mutations was associated with increased mortality (mortality rate ratio [MRR] 2.3 [95% confidence interval (CI) 1.1–4.8]), as were the individual mutations T215Y (MRR 3.4 [95% CI 1.6–7.0]), G190A/S (MRR 3.2 [95% CI 1.6–6.6]) and V82F/A/T/S (MRR 2.5 [95% CI 1.2–5.3]).

Conclusions

In HIV patients with TCF, the total number of genotypic resistance mutations and specific single mutations predicted mortality.

Drug-Sparing Regimens for HIV Combination Therapy: Benefits Predicted for “Drug Coasting”

Structured Treatment Interruptions (STI) during HIV drug therapy were thought to potentially reduce side effects and toxicity, boost immune involvement, and possibly lower the viral set-point. Clinical trials of STI regimens, however, have had mixed results. We use an established mathematical model of HAART to estimate possible therapeutic outcomes for STI and for other, similar patterns in HIV combination therapy. We perform an exhaustive search of patterns of up to 60 days, for triple-drug combinations involving accurate pharmacokinetics for 12 specific antiviral drugs. The results of this analysis are consistent with recent clinical trials which have demonstrated that STI-type patterns, involving therapy interruption of weeks or months, are rarely optimal. Our analysis predicts, however, that the benefit of treatment can often be improved by including very short drug-free periods, during which the patient effectively "coasts" for a day or two on adequate drug concentrations due to the long half-life of some pharmaceuticals. Our analysis predicts many cases in which this may be achieved without increasing the risk of drug-resistance. This suggests that "drug coasting" patterns, significantly shorter than STI patterns, may merit further clinical investigation in efforts to find drug-sparing regimens for HIV.

Optimal drug treatment regimens for HIV depend on adherence

Drug therapies aimed at suppressing the human immunodeficiency virus (HIV) are highly effective, often reducing the viral load to below the limits of detection for years. Adherence to such antiviral regimens, however, is typically far from ideal. We have previously developed a model that predicts optimal treatment regimens by weighing drug toxicity against CD4+ T-cell counts, including the probability that drug resistance will emerge. We use this model to investigate the influence of adherence on therapy benefit. For a drug with a given half-life, we compare the effects of varying the dose amount and dose interval for different rates of adherence, and compute the optimal dose regimen for adherence between 65% and 95%. Our results suggest that for optimal treatment benefit, drug regimens should be adjusted for poor adherence, usually by increasing the dose amount and leaving the dose interval fixed. We also find that the benefit of therapy can be surprisingly robust to poor adherence, as long as the dose interval and dose amount are chosen accordingly.

Evolution of HIV resistance mutations in patients maintained on a stable treatment regimen after virologic failure

OBJECTIVE

We compared the rate of emergence of thymidine analogue mutations (TAMs) and major protease inhibitor mutations in adherent patients who remained on stable treatment with a thymidine analogue and/or protease inhibitor after the onset of virologic failure.

DESIGN

Follow-up genotypic resistance testing was done using archived plasma obtained from patients having 0 or 1 TAM and/or 0 or 1 major protease inhibitor resistance mutation at the onset of virologic failure.

RESULTS

The median duration of observed failure was 691 days. There were 41 thymidine analogue regimens and 34 protease inhibitor regimens; concomitant ritonavir was used 4 times. New major protease inhibitor mutations emerged more rapidly than did new TAMs (P = 0.0019); new TAMs emerged more rapidly in thymidine analogue regimens that did not include lamivudine (P = 0.0073). The emergence of TAMs and major protease inhibitor mutations did not differ if lamivudine was not part of the thymidine analogue regimen. The evolution of CD4 cell counts and plasma viral loads (pVLs) during virologic failure was similar regardless of whether or not a new TAM or major protease inhibitor mutations emerged or, for thymidine analogue-containing regimens, whether lamivudine was or was not used.

CONCLUSIONS

Major protease inhibitor mutations arose more frequently and rapidly than did TAMs in patients with sustained virologic failure who received lamivudine.

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.