Rational use of antiretroviral therapy in low-income and middle-income countries: optimizing regimen sequencing and switching

Understanding adherence in virally suppressed and unsuppressed human immunodeficiency virus-positive urban patients on second-line antiretroviral treatment

Background

Understanding antiretroviral therapy (ART) adherence may assist in designing effective support interventions.

Objectives

This study elicited perspectives on how to promote treatment adherence from virologically suppressed and unsuppressed patients receiving second-line ART.

Methods

This was a cross-sectional study conducted with randomly selected patients active on second-line ART, from five public health facilities in the Johannesburg inner city. Data were collected on demographics, clinical information, participant’s experiences and ART knowledge. Virological failure was defined as exceeding 1000 copies/mL.

Results

The study sample comprised 149 participants; of which 47.7% (n = 71) were virally unsuppressed and 69.1% (n = 103) were women; the median age of the participants was 42 years (interquartile range [IQR] 36–47 years). Experiencing medication-related difficulties in taking second-line ART (p = 0.003), finding second-line regimen more difficult to take than a first-line regimen (p = 0.001) and experiencing side effects (p < 0.001) were all subjective predictors of virological failure. Participants’ recommendations for improving adherence included the introduction of a single tablet regimen (31.6%, n = 55), reducing the dosage to once daily (26.4%, n = 46) and reducing the pill size for second-line regimen (4.0%, n = 7).

Conclusion

The results of this study highlight the importance of improving patients’ knowledge about adherence and motivation to continue ART use despite the persistence of side effects and difficulties with taking medication.

Second line antiretroviral therapy for treatment of HIV in Asia

Limited access to virological monitoring has led to a high prevalence of resistance to nucleoside reverse transcriptase inhibitors (NRTIs) at the time of first line failure in most studies from low- and middle-income countries (LMIC). Nevertheless, the current standard of care is to include NRTIs in second line regimens. The activity of tenofovir/emtricitabine following failure of stavudine/lamivudine or zidovudine/lamivudine is dependent on the sensitivity of the monitoring strategy used during first line therapy and the threshold for switching, whereas these factors are less important if the opposite sequencing strategy is used. Boosted protease inhibitors (PIs) are the foundation of effective second-line therapy with demonstrated efficacy in early salvage regimens and high barrier to resistance. Lopinavir/ritonavir and ritonavir-boosted atazanavir have recently been described by the World Health Organization as preferred boosted PIs for use in LMIC. Alternative approaches currently under investigation include boosted PI monotherapy, dual boosted PIs, and the combination of raltegravir (an HIV integrase inhibitor) and a boosted PI.

Magnitude and Predictors of Anti-Retroviral Treatment (ART) Failure in Private Health Facilities in Addis Ababa, Ethiopia

BACKGROUND

The public health approach to antiretroviral treatment management encourages the public private partnership in resource limited countries like Ethiopia. As a result, some private health facilities are accredited to provide antiretroviral treatment free services. Evidence on magnitude and predictors of treatment failure are crucial for timely actions. However, there are few studies in this regard.

OBJECTIVE

To assess the magnitude and predictors of ART failure in private health facilities in Addis Ababa, Ethiopia.

METHODS

The study followed retrospective cohort design, with 525 adult antiretroviral treatment clients who started the treatment since October 2009 and have at least six months follow up until December 31, 2013. Kaplan Meier survival analysis and Cox proportional hazard model were used for analysis.

RESULTS

Treatment failure, using the three WHO antiretroviral treatment failure criteria, was 19.8%. The immunologic, clinical, and virologic failures were 15%, 6.3% and 1.3% respectively. The mean and median survival times in months were 41.17 with 95% Confidence Interval (CI) [39.69, 42.64] and 49.00, 95% CI [47.71, 50.29] respectively. The multivariate cox regression analysis showed years since HIV diagnosis (Adjusted Hazard Ratio (AHR)=13.87 with 95% CI [6.65, 28.92]), disclosure (AHR=0.59, 95% CI [0.36, 0.96]), WHO stage at start (AHR=1.84, 95% CI [1.16, 2.93]), weight at baseline (AHR=0.58, 95% CI [0.38, 0.89]), and functionality status at last visit (AHR=2.57, 95% CI [1.59, 4.15]) were independent predictors of treatment failure.

CONCLUSION

The study showed that the treatment failure is high among the study subjects. The predictors for antiretroviral treatment failure were years since HIV diagnosis, weight at start, WHO stage at start, status at last visit and disclosure.

RECOMMENDATIONS

Facilities need to monitor antiretroviral treatment clients to avoid disease progression and drug resistance.

Optimal Treatment Strategies in the Context of 'Treatment for Prevention' against HIV-1 in Resource-Poor Settings

An estimated 2.7 million new HIV-1 infections occurred in 2010. `Treatment-for-prevention’ may strongly prevent HIV-1 transmission. The basic idea is that immediate treatment initiation rapidly decreases virus burden, which reduces the number of transmittable viruses and thereby the probability of infection. However, HIV inevitably develops drug resistance, which leads to virus rebound and nullifies the effect of `treatment-for-prevention’ for the time it remains unrecognized. While timely conducted treatment changes may avert periods of viral rebound, necessary treatment options and diagnostics may be lacking in resource-constrained settings. Within this work, we provide a mathematical platform for comparing different treatment paradigms that can be applied to many medical phenomena. We use this platform to optimize two distinct approaches for the treatment of HIV-1: (i) a diagnostic-guided treatment strategy, based on infrequent and patient-specific diagnostic schedules and (ii) a pro-active strategy that allows treatment adaptation prior to diagnostic ascertainment. Both strategies are compared to current clinical protocols (standard of care and the HPTN052 protocol) in terms of patient health, economic means and reduction in HIV-1 onward transmission exemplarily for South Africa. All therapeutic strategies are assessed using a coarse-grained stochastic model of within-host HIV dynamics and pseudo-codes for solving the respective optimal control problems are provided. Our mathematical model suggests that both optimal strategies (i)-(ii) perform better than the current clinical protocols and no treatment in terms of economic means, life prolongation and reduction of HIV-transmission. The optimal diagnostic-guided strategy suggests rare diagnostics and performs similar to the optimal pro-active strategy. Our results suggest that ‘treatment-for-prevention’ may be further improved using either of the two analyzed treatment paradigms.

HIV-1 continues to spread globally. Antiviral treatment cannot cure patients, but it slows disease progression and may prevent HIV transmission by decreasing the amount of transmittable viruses in treated individuals. ‘Treatment-for-prevention’ argues for immediate treatment initiation and may reduce transmission by 96% (CI: 73–99%), according to the results of a large clinical study (HPTN052). In order to ensure long-lasting treatment success, early therapy initiation demands more sophisticated treatment strategies & exceeding funds. However, countries facing the highest HIV burden are among the poorest. Within this work, we provide a mathematical framework that allows assessing different treatment paradigms using optimal control theory together with stochastic modelling of within-host viral dynamics and drug resistance development. We use this framework to compute and evaluate two distinct optimal long-term treatment strategies for resource-constrained settings: (i) a diagnostic-guided and (ii) a pro-active treatment strategy. The cost of a strategy is evaluated from a national economic perspective, valuating a severe patient health status in terms of an economic loss. The optimal strategies are compared with current clinical treatment protocols and no treatment in terms of costs, life expectation and reduction of secondary cases. Our simulations indicate that the pro-active treatment strategy performs comparably to the diagnostic-guided treatment strategy. Both strategies perform better than current clinical protocols, suggesting directions for improvement.

Effectiveness of first-line antiretroviral therapy in the IPEC cohort, Rio de Janeiro, Brazil

BACKGROUND

While Brazil has had a long-standing policy of free access to antiretroviral therapy (ART) for all in need, the epidemiological impact of ART on human immunodeficiency virus (HIV) RNA suppression in this middle-income country has not been well evaluated. We estimate first-line ART effectiveness in a large Brazilian cohort and examine the socio-demographic, behavioral, clinical and structural factors associated with virologic suppression.

METHODS

Virologic suppression on first-line ART at 6, 12, and 24 months from start of ART was defined as having a viral load measurement ≤400 copies/mL without drug class modification and/or discontinuation. Drug class modification and/or discontinuation were defined based on the class of a particular drug. Quasi-Poisson regression was used to quantify the association of factors with virologic suppression.

RESULTS

From January 2000 through June 2010, 1311 patients started first-line ART; 987 (75%) patients used NNRTI-based regimens. Virologic suppression was achieved by 77%, 76% and 68% of patients at 6, 12 and 24 months, respectively. Factors associated with virologic suppression at 12 months were: >8 years of formal education (compared to <4 years, risk ratio (RR) 1.13, 95% confidence interval (95% CI) 1.03-1.24), starting ART in 2005-2010 (compared to 2000-2004, RR 1.25 95% CI 1.15-1.35), and clinical trial participation (compared to no participation, RR 1.08 95% CI 1.01-1.16). Also at 12 months, women showed less virologic suppression compared to heterosexual men (RR 0.90 95% CI 0.82-0.99). For the 24-month endpoint, in addition to higher education, starting ART in the later period, and clinical trial participation, older age and an NNRTI-based regimen were also independently associated with virologic suppression.

CONCLUSIONS

Our results show that in Brazil, a middle-income country with free access to treatment, over three-quarters of patients receiving routine care reached virologic suppression on first-line ART by the end of the first year. Higher education, more recent ART initiation and clinical trial participation were associated with improved outcomes both for the 12-month and the 24-month endpoints, suggesting that further studies are needed to understand what aspects relating to these factors lead to higher virologic suppression.

Phenotypic and genotypic analyses to guide selection of reverse transcriptase inhibitors in second-line HIV therapy following extended virological failure in Uganda

Objectives

We investigated phenotypic and genotypic resistance after 2 years of first-line therapy with two HIV treatment regimens in the absence of virological monitoring.

Methods

NORA [Nevirapine OR Abacavir study, a sub-study of the Development of AntiRetroviral Therapy in Africa (DART) trial] randomized 600 symptomatic HIV-infected Ugandan adults (CD4 cell count <200 cells/mm³) to receive zidovudine/lamivudine plus abacavir (cABC arm) or nevirapine (cNVP arm). All virological tests were performed retrospectively, including resistance tests on week 96 plasma samples with HIV RNA levels ≥1000 copies/mL. Phenotypic resistance was expressed as fold-change in IC₅₀ (FC) relative to wild-type virus.

Results

HIV-1 RNA viral load ≥1000 copies/mL at week 96 was seen in 58/204 (28.4%) cABC participants and 21/159 (13.2%) cNVP participants. Resistance results were available in 35 cABC and 17 cNVP participants; 31 (89%) cABC and 16 (94%) cNVP isolates had a week 96 FC below the biological cut-off for tenofovir (2.2). In the cNVP arm, 16/17 participants had resistance mutations synonymous with high-level resistance to nevirapine and efavirenz; FC values for etravirine were above the biological cut-off in 9 (53%) isolates. In multivariate regression models, K65R, Y115F and the presence of thymidine analogue-associated mutations were associated with increased susceptibility to etravirine in the cABC arm.

Conclusions

Our data support the use of tenofovir following failure of a first-line zidovudine-containing regimen and shed further light on non-nucleoside reverse transcriptase inhibitor hypersusceptibility.

A prospective study of haematological changes after switching from stavudine to zidovudine-based antiretroviral treatment in HIV-infected children

Long-term use of stavudine is associated with a high incidence of lipodystrophy, warranting its substitution with zidovudine in first-line antiretroviral therapy (ART) regimens. In a prospective observational study, we determined the spectrum and severity of haematological changes after switching from stavudine- to zidovudine-based ART in Indian children aged 2-18 years who had received a stavudine-based ART regimen for at least 48 weeks. They were followed for 48 weeks for changes in haematological parameters and CD4 cell counts after switching to zidovudine. Of the 60 children analysed, 45 (75%) showed a significant fall in Hb (>1 g/dl). A majority developed grade 1 anaemia (14 [31%]) while only three (6%) developed grade 4 anaemia. The lowest Hb was recorded between 12 and 16 weeks with spontaneous improvement noticed after 28 weeks. A significant drop in absolute neutrophil count (5067 cells/mm³ to 3625 cells/mm³; p = 0.004) was also observed but none developed severe neutropenia. No significant changes were observed in platelet and CD4 cell counts. Since the incidence of severe drug toxicity was low with zidovudine and the majority of children recovered without intervention, drug toxicity should not preclude its routine use in poor countries.

Targets for intervention to improve virological outcomes for patients receiving free antiretroviral therapy in Tamil Nadu, India

Operational research to identify factors predicting poor clinical outcomes is critical to maximize patient care and prolong first-line regimens for those receiving free antiretroviral therapy (ART) in India. We sought to identify social or clinical factors amenable to intervention that predict virological outcomes after 12 months of ART. We examined a retrospective cohort of consecutive adults initiating free nonnucleoside reverse transcriptase inhibitor-based regimens. Individuals remaining in care 12 months post-ART initiation were tested for HIV viral load and surveyed to identify barriers and facilitators to adherence, and to determine clinic travel times and associated costs. Uni- and multivariate logistic regression identified factors predicting HIV viral load >200 copies/mL after 12 months of ART. Of 230 adults initiating ART, 10% of patients died, 8% transferred out, 5% were lost to follow-up, and 174/230 (76%) completed 12 months of ART, the questionnaire, and viral load testing. HIV viral load was <200 copies/mL in 140/174 (80%) patients. In multivariate models, being busy with work or caring for others (OR 2.9, p < 0.01), having clinic transport times ≥ 3 hours (OR 3.0, p = 0.02), and alcohol use (OR 4.8, p = 0.03) predicted viral load >200 copies/mL after 12 months of ART. Clinical outcomes following ART are related to programmatic factors such as prolonged travel time and individual factors such as being busy with family or using alcohol. Simple interventions that alter these factors should be evaluated to improve clinical outcomes for populations receiving free ART in similar settings.

Pharmacy and self-report adherence measures to predict virological outcomes for patients on free antiretroviral therapy in Tamil Nadu, India

Over 480,000 individuals receive free antiretroviral therapy (ART) in India yet data associating ART adherence with HIV viral load for populations exclusively receiving free ART are not available. Additionally estimates of adherence using pharmacy data on ART pick-up are not available for any population in India. After 12-months ART we found self-reported estimates of adherence were not associated with HIV viral load. Individuals with <100% adherence using pharmacy data predicted HIV viral load, and estimates combining pharmacy data and self-report were also predictive. Pharmacy adherence measures proved a feasible method to estimate adherence in India and appear more predictive of virological outcomes than self-report. Predictive adherence measures identified in this study warrant further investigation in populations receiving free ART in India to allow for identification of individuals at risk of virological failure and in need of adherence support.

Evaluation of clinical and immunological markers for predicting virological failure in a HIV/AIDS treatment cohort in Busia, Kenya

BACKGROUND

In resource-limited settings where viral load (VL) monitoring is scarce or unavailable, clinicians must use immunological and clinical criteria to define HIV virological treatment failure. This study examined the performance of World Health Organization (WHO) clinical and immunological failure criteria in predicting virological failure in HIV patients receiving antiretroviral therapy (ART).

METHODS

In a HIV/AIDS program in Busia District Hospital, Kenya, a retrospective, cross-sectional cohort analysis was performed in April 2008 for all adult patients (>18 years old) on ART for ≥12 months, treatment-naive at ART start, attending the clinic at least once in last 6 months, and who had given informed consent. Treatment failure was assessed per WHO clinical (disease stage 3 or 4) and immunological (CD4 cell count) criteria, and compared with virological failure (VL >5,000 copies/mL).

RESULTS

Of 926 patients, 123 (13.3%) had clinically defined treatment failure, 53 (5.7%) immunologically defined failure, and 55 (6.0%) virological failure. Sensitivity, specificity, positive predictive value, and negative predictive value of both clinical and immunological criteria (combined) in predicting virological failure were 36.4%, 83.5%, 12.3%, and 95.4%, respectively.

CONCLUSIONS

In this analysis, clinical and immunological criteria were found to perform relatively poorly in predicting virological failure of ART. VL monitoring and new algorithms for assessing clinical or immunological treatment failure, as well as improved adherence strategies, are required in ART programs in resource-limited settings.

Prognostic value of virological and immunological responses after 6 months of antiretroviral treatment in adults with HIV-1 infection in sub-Saharan Africa

BACKGROUND

HIV RNA monitoring is not available in most antiretroviral treatment (ART) programs in sub-Saharan Africa; switch to second-line therapy is mostly guided by clinical/immunological criteria. This may lead to unnecessary disease progression and drug resistance accumulation. We investigated the prognostic value of virological and immunological status 6 months after ART initiation with respect to death, loss to follow-up, and treatment switch.

METHODS

We considered treatment-naive HIV-1-infected patients, starting ART with available 6-month visit and subsequent follow-up, enrolled in a prospective cohort comprising 5 ART sites in 3 sub-Saharan countries. Outcome measures included the time from 6-month visit to death for all causes, loss to follow-up, and switch to second line.

RESULTS

Of 2539 patients, 62% were females, their median pre-ART CD4 count was 215 cells per microliter, median HIV RNA 4.6 Log10 copies per milliliter, 30% were on WHO stage 3/4. At 6 months, 85% had HIV RNA <1000 copies per milliliter. During 3112 person-years follow-up after the 6-month visit, 91 patients died. Death was predicted by 6-month HIV RNA ≥10,000 copies per milliliter, adherence, and 6-month CD4 <200 cells per microliter. The 2-year estimated probability of surviving ranged from 0.69 (with 6-month HIV RNA ≥10,000 and CD4 <200) to 0.95 (with HIV RNA <1000 and CD4 ≥200). Loss to follow-up (1.95 per 100 person-years follow-up) was predicted by the 6-month HIV RNA >10,000 copies per milliliter and adherence but not by CD4. Switch to second line (6.94 per 100 person-years follow-up) was predicted by 6-month HIV RNA and CD4.

CONCLUSIONS

In patients starting ART in sub-Saharan Africa, 6-month HIV RNA independently predicts subsequent survival, retention to care, and switch to second-line therapy. This measure warrants further evaluation as specific time point monitoring option.

Early outcomes and the virological effect of delayed treatment switching to second-line therapy in an antiretroviral roll-out programme in South Africa

BACKGROUND

More patients in resource-limited settings are starting second-line antiretroviral treatment (ART) following first-line ART failure. We aimed to describe predictors of lack of virological suppression in HIV-infected patients on second-line ART in a roll-out programme in South Africa.

METHODS

A retrospective analysis was performed on an adult HIV treatment cohort who started second-line ART (lopinavir/ritonavir, didanosine and zidovudine) after virological failure of first-line ART (two consecutive HIV RNA>1,000 copies/ml). Predictors of week 24 lack of suppression (HIV RNA>400 copies/ml) on second-line ART were determined by bivariate analysis where missing equals failure. A multivariable model that adjusted for gender, age and time to ART switch was used. We tested these findings in sensitivity analyses defining lack of suppression at week 24 as HIV RNA>1,000 and >5,000 copies/ml.

RESULTS

Of 6,339 patients on ART, 202 started second-line ART. At week 24, an estimated 41% (95% CI 34-47) did not achieve virological suppression. Female sex (adjusted OR 2.25, 95% CI 1.03-4.88) and time to ART switch (adjusted OR 1.07, 95% CI 1.01-1.14 for each additional month) increased the risk of lack of virological suppression. Age, CD4(+) T-cell count and HIV RNA at second-line ART initiation did not predict this outcome. In multivariate models, these findings were insensitive to the definition of lack of virological suppression.

CONCLUSIONS

A substantial number of HIV-infected patients do not achieve virological suppression by week 24 of second-line ART. Women and patients with delayed start of second-line ART after first-line ART failure were at an increased risk of lack of virological suppression.

Evaluating patients for second-line antiretroviral therapy in India: the role of targeted viral load testing

BACKGROUND

The identification and management of first-line antiretroviral therapy (ART) failure is a key challenge for HIV programs in resource-limited settings. In 2008, the National AIDS Control Organisation, India piloted a national strategy to provide second-line ART. We assessed the National AIDS Control Organisation second-line ART evaluation algorithm.

METHODS

Adult patients who had received 6 months or more of standard first-line ART were referred for second-line ART evaluation if they demonstrated CD4 decline to pre-ART values, CD4 drop to less than 50% of peak on-treatment value, failure to achieve CD4 greater than 100 c/mm(3), or development of a new World Health Organization Stage 3 or 4 AIDS-defining illness. Patients received HIV RNA testing, and those with HIV RNA 10,000 c/mL or greater qualified to switch to second-line ART. World Health Organization-defined clinical and CD4 criteria for ART failure were compared against virologic failure criteria.

RESULTS

Between January and June 2008, 154 patients met criteria for evaluation. Of 122 (79%) patients who had HIV RNA testing, 87 (71%) had viral load 10,000 c/mL or greater and were recommended to start second-line ART, 29 (24%) had viral load less than 400 c/mL, and six (5%) had viral load between 400 and 10,000 c/mL. The positive predictive value of World Health Organization clinical/immunologic criteria to detect virologic failure was 71% (95% confidence interval, 63% to 79%).

CONCLUSIONS

Second-line ART was initiated in the public sector in India using an approach combining clinical and immunologic evaluation with confirmation of virologic failure. Almost 25% of patients who met clinical/immunologic failure criteria demonstrated virologic suppression. Inclusion of targeted HIV RNA testing in the evaluation of treatment failure can prevent unnecessary switches to second-line ART.

Treatment switching in South Indian patients on HAART: what are the predictors and consequences?

Early identification and management of treatment failure on highly active antiretroviral therapy (HAART) is crucial in maintaining a sustained response to therapy in HIV infection. However, HIV viral load (VL) and resistance testing, and second-line HAART regimens, are unaffordable to many patients in India, leaving them with limited treatment options. Predictors and reasons for antiretroviral switching, therefore, are likely to differ in settings of varying resources. A one-year, observational study of patients receiving antiretroviral therapy was conducted in a private, non-profit hospital in Bangalore. This paper examines the predictors and consequences of antiretroviral treatment switching in this setting and explores reasons for switching in a subset of patients. Data on demographics, drug regimens, adherence, and physical and psychosocial outcomes were collected quarterly. Tests of VL and CD4 cell counts were performed every six months. One-third of the patients switched therapy during the study period. Baseline predictors of switching included lower CD4 cell counts and more physical symptoms. Contrary to studies in other settings, a high VL did not predict treatment switching, and only a minority of those experiencing drug failure were switched to second-line regimens. Both groups (switchers and non-switchers) improved significantly over time with respect to CD4 counts and psychological well-being, and showed a reduction in physical and depressive symptoms. Any differences between the groups were no longer significant at the end of the study, once we controlled for baseline levels. Clinical, policy, and research implications of these findings are discussed within the context of resource-limited settings.

Alternative antiretroviral monitoring strategies for HIV-infected patients in east Africa: opportunities to save more lives?

Background

Updated World Health Organization guidelines have amplified debate about how resource constraints should impact monitoring strategies for HIV-infected persons on combination antiretroviral therapy (cART). We estimated the incremental benefit and cost effectiveness of alternative monitoring strategies for east Africans with known HIV infection.

Methods

Using a validated HIV computer simulation based on resource-limited data (USAID and AMPATH) and circumstances (east Africa), we compared alternative monitoring strategies for HIV-infected persons newly started on cART. We evaluated clinical, immunologic and virologic monitoring strategies, including combinations and conditional logic (e.g., only perform virologic testing if immunologic testing is positive). We calculated incremental cost-effectiveness ratios (ICER) in units of cost per quality-adjusted life year (QALY), using a societal perspective and a lifetime horizon. Costs were measured in 2008 US dollars, and costs and benefits were discounted at 3%. We compared the ICER of monitoring strategies with those of other resource-constrained decisions, in particular earlier cART initiation (at CD4 counts of 350 cells/mm³ rather than 200 cells/mm³).

Results

Monitoring strategies employing routine CD4 testing without virologic testing never maximized health benefits, regardless of budget or societal willingness to pay for additional health benefits. Monitoring strategies employing virologic testing conditional upon particular CD4 results delivered the most benefit at willingness-to-pay levels similar to the cost of earlier cART initiation (approximately $2600/QALY). Monitoring strategies employing routine virologic testing alone only maximized health benefits at willingness-to-pay levels (> $4400/QALY) that greatly exceeded the ICER of earlier cART initiation.

Conclusions

CD4 testing alone never maximized health benefits regardless of resource limitations. Programmes routinely performing virologic testing but deferring cART initiation may increase health benefits by reallocating monitoring resources towards earlier cART initiation.

Genotypic impact of prolonged detectable HIV type 1 RNA viral load after HAART failure in a CRF01_AE-infected cohort

HIV subtype-specific data on mutation type, rate, and accumulation following HAART treatment failure are limited. We studied patterns and accrual of drug resistance mutations in a Cambodian CRF01_AE-infected cohort continuing a virologically failing first-line, nonnucleoside reverse transcriptase inhibitor- (NNRTI-) based, HAART. Between 2005 and 2007, 837 adult HIV-infected patients had regular plasma HIV-1 RNA viral load measurements at Sihanouk Hospital Centre of Hope (SHCH), Cambodia. Drug resistance testing was performed in all patients with HIV-1 RNA >1000 copies/ml after at least 6 months of HAART. Seventy-one patients with a mean age of 34 years, of whom 68% were male, were retrospectively assessed at virological failure. The median duration of antiretroviral therapy was 12.3 (IQR 7.1-18.23) months, the median CD4 cell count was 173 (IQR 118-256) cells/mm(3), and the mean plasma HIV-1 RNA viral load was 3.9 log (SD 0.72) at failure. NNRTI mutations, M184I/V mutation, thymidine analogue mutations, and K65R were observed in 78.9%, 69%, 20%, and 12.7% of patients, respectively. For 33 patients, genotypic testing was carried out on at least two occasions before the switch to second-line HAART after a median duration of 5.8 (IQR 4.3-6.1) months of virological failure: 54.5% of patients accumulated new mutations with a rate of 1.6 mutations per person-year. Accumulation was seen both for nucleoside and nonnucleoside reverse transcriptase inhibitors, and also in patients with low-level viremia. Subtype-specific data on mutation type, rate, and accumulation after HAART failure are urgently needed to optimize treatment strategies in resource-limited settings.

Effect on transmission of HIV-1 resistance of timing of implementation of viral load monitoring to determine switches from first to second-line antiretroviral regimens in resource-limited settings

BACKGROUND

There is concern that antiretroviral therapy (ART) use with only clinical monitoring for failure will result in high rates of transmission of virus with resistance to drugs currently in use.

METHODS

A stochastic simulation model of transmission of HIV, natural history and the effect of ART, was developed and used to predict the proportion of new infections with resistance according to whether and when viral load monitoring is introduced.

RESULTS

In our base model, there was predicted to be 12.4% of new HIV infections with primary antiretroviral resistance in 2020 if clinical monitoring is used throughout, compared with 5.4 and 6.1% if viral load-guided switching (based on viral load measured every 6 months, with switch determined by a value >500 copies/ml) was introduced in 2010 or 2015, respectively. The death rate for those on ART was lowest when viral load monitoring was used, but the overall death rate in all infected people was higher if viral load monitoring was introduced at the expense of scale-up in HIV diagnosis and ART initiation beyond their 2010 coverage levels (4.7 compared with 3.1 per 100 person-years).

INTERPRETATION

To preserve current first-line drugs for the long term there is an eventual need for some form of cheap and practical viral load monitoring in resource-limited settings. However, a delay in introduction of 5 years has limited consequences for resistance transmission so the current priority for countries' ART programmes is to increase HIV testing and provide treatment for all those in need of ART.

Evolution of drug resistance during 48 weeks of zidovudine/lamivudine/tenofovir in the absence of real-time viral load monitoring

OBJECTIVES

To describe the resistance mutations selected by a first-line regimen of zidovudine/lamivudine/tenofovir in the absence of real-time viral load monitoring.

DESIGN

A substudy of 300 participants from the Development of Antiretroviral Therapy in Africa trial in Uganda and Zimbabwe, which compared managing antiretroviral therapy with and without laboratory monitoring.

METHODS

Stored plasma samples from selected time points were assayed retrospectively for HIV-1 RNA. The pol gene in all baseline samples and those with HIV RNA >1000 copies per milliliter at weeks 24 and 48 were sequenced.

RESULTS

The proportion with HIV RNA >1000 copies per milliliter increased from 15% at 24 weeks to 24% at 48 weeks. Eighteen of 31 (58%) genotyped samples at 24 weeks had ≥ 1 major nucleoside reverse transcriptase inhibitor-associated mutations compared with 41 of 47 (87%) at 48 weeks. Excluding 1 nonadherent patient, a mean of 2.0 (95% confidence interval: 1.3 to 2.8) thymidine analogue mutations (TAMs) developed between weeks 24 and 48 among 14 patients with HIV RNA >1000 copies per milliliter at both time points. K65R was detected in 8 of 63 (13%) patients and was negatively associated with number of TAMs (P = 0.01) but not viral subtype (P = 0.30).

CONCLUSIONS

A high rate of acquisition of TAMs, but not of K65R, among patients with prolonged viraemia was observed. However, most patients were virologically suppressed at 48 weeks, and long-term clinical and immunological outcomes in the Development of Antiretroviral Therapy in Africa trial were favorable.

Optimal monitoring strategies for guiding when to switch first-line antiretroviral therapy regimens for treatment failure in adults and adolescents living with HIV in low-resource settings

BACKGROUND

One of the critical clinical decisions made in antiretroviral therapy (ART) is when to switch from an initial regimen to another due to treatment failure. This complex process requires consideration of multiple factors including: (1) what type of monitoring (e.g. clinical, immunologic, virologic) is available to guide switching; (2) establishing criteria for treatment failure (e.g. viral load >10,000 copies/mL); (3) integrating data from different types of monitoring; (4) making a decision; and, if possible, (5) follow-up and monitoring to determine patient outcomes. The initial step in this model of deciding when to switch is determining what type of monitoring for guiding when to switch is available and appropriate. This review seeks to find and summarize evidence on optimal monitoring strategies for guiding when to switch first-line regimens due to treatment failure among adults and adolescents living with HIV in low-resource settings. This review was one of a series of reviews prepared in 2009 at the request of the World Health Organization to inform the development of new guidelines on ART for adults and adolescents.

OBJECTIVES

To assess optimal monitoring strategies for guiding when to switch antiretroviral therapy regimens for first-line treatment failure among adults and adolescents living with HIV in low-resource settings.

SEARCH STRATEGY

We formulated a comprehensive and exhaustive search strategy in an attempt to identify all relevant studies regardless of language or publication status. In July 2009, we search the following electronic journal and trial databases: MEDLINE, EMBASE, CENTRAL. We also searched conference databases using NLM Gateway (for HIV/AIDS conference abstracts before 2005), abstract databases from the Conferences on Retroviruses and Opportunistic Infections, International AIDS Conferences, and International AIDS Society Conferences on HIV Pathogenesis, Treatment, and Prevention from 2005 to 2009, and the trials registers ClinicalTrials.gov, Current Controlled Trials, and Pan-African Clinical Trials Registry. We contacted researchers and relevant organizations and checked reference lists for all included studies.

SELECTION CRITERIA

We selected studies which evaluated a monitoring intervention/strategy that helps guide when to switch ART. Study types included randomized controlled trials and observational studies (cohort and case-control) which included comparators.

DATA COLLECTION AND ANALYSIS

One author performed an initial screening. Two authors performed a detailed screening. Two authors independently assessed study eligibility, extracted data, and graded methodological quality. Differences were resolved by a third reviewer. Heterogeneity was assessed, and meta-analyses were performed where appropriate.

MAIN RESULTS

Two randomized trials were identified which were in abstract form only. Two cohort studies (both published) with comparators were identified. Of the evidence available, three comparisons were studied: clinical versus immunologic and clinical monitoring; clinical versus virologic, immunologic, and clinical monitoring; and immunologic and clinical monitoring versus virologic, immunologic, and clinical monitoring. Clinical vs. Immunologic and Clinical Monitoring: Based upon two randomized trials, clinical monitoring alone results in increased mortality (low-quality evidence), increased AIDS-defining illnesses and mortality as a composite endpoint (moderate), no difference in serious adverse events (low), increased numbers of unnecessary switches (low), and no difference in switches to second-line (low) compared to immunological and clinical monitoring. Clinical vs. Virologic, Immunologic, and Clinical Monitoring: Based upon a single randomized trial, clinical monitoring alone results in a trend toward increased mortality (low), increased AIDS-defining illnesses and mortality as a composite endpoint (low), increased unnecessary switches (low), no difference in virologic treatment failures (low), and a trend toward increased switches to second-line (low) compared to virologic, immunologic, and clinical monitoring. Immunologic and Clinical vs. Virologic, Immunologic, and Clinical Monitoring: Based upon a single randomized trial, immunologic and clinical monitoring results in no difference in mortality (low), no difference in AIDS-defining illnesses and mortality as a composite endpoint (low), no difference in unnecessary switches (very low), no difference in virologic treatment failures (low), and no difference in switches to second-line (low) compared to virologic, immunologic, and clinical monitoring. Observational studies appear to demonstrate that programs with virologic, immunologic, and clinical monitoring switch therapy more frequently (very low), earlier (very low), and at higher CD4 counts (very low) compared with programs that have immunologic and clinical monitoring alone.

AUTHORS' CONCLUSIONS

A limited number of studies were available to address this topic, and, of the two randomized trials identified, both were in abstract form only. Observational studies also were limited in number and were of lesser quality. Although the quality of the evidence varied from the randomized trials, ranging from very low to moderate, there appeared to be substantial benefits for key outcomes (e.g. mortality, AIDS-defining illness and mortality as a composite endpoint, and unnecessary switches) favoring both immunologic and clinical monitoring or virologic, immunologic, and clinical monitoring versus clinical monitoring alone. Very low-quality evidence from observational studies suggested that virologic, immunologic, and clinical monitoring led to more frequent switching, earlier switching, and switching at higher CD4 counts compared with immunologic and clinical monitoring. Further information on the studies currently reported in abstract form will provide insight. Ongoing studies addressing this topic likely will provide information to further clarify optimal monitoring strategies for guiding when to switch first-line therapy. Additionally, studies looking at different virologic monitoring frequencies and/or virologic monitoring at different times after ART initiation (e.g. after 2-3 years) would be informative. Finally, cost-analysis studies will lend further insights into the applicability of these findings to low-resource settings.

Resistance considerations in sequencing of antiretroviral therapy in low-middle income countries with currently available options

PURPOSE OF REVIEW

Access to antiretroviral therapy (ART) has been scaled-up in low-middle income countries (LMICs), where the majority of the world's HIV-1-infected population is living. Concerns towards the emergence and spread of HIV-1 drug resistance exist, given the lack of virological monitoring which may give rise to accumulation of resistance as well as the use of suboptimal ART in pregnant women with the aim to reduce perinatal transmission. Knowledge of the prevalence of transmitted and emerging drug resistance as well as its specific patterns is of help in guiding the selection of appropriate ART types and sequencing strategies.

RECENT FINDINGS

Whereas transmitted drug resistance in LMIC is still limited, resistance in pregnant women as a consequence of suboptimal ART for the prevention of vertical transmission is frequent and dependent on viral subtype and load. Accumulation of drug resistance during first-line ART depends on the frequency of monitoring, whereas mutational patterns are influenced by type of ART and, partly, viral subtype.

SUMMARY

Optimized ART for prevention of mother-to-child transmission and closer monitoring of ART programs with the inclusion of viral load may help reducing unnecessary development of HIV drug resistance in LMIC and preserve the limited available treatment options.

Monitoring for treatment failure in patients on first-line antiretroviral treatment in resource-constrained settings

PURPOSE OF REVIEW

The number of people living with HIV in low-income and middle-income countries (LMICs), who will fail first-line treatment and benefit from regimen switching, will steadily increase in the coming years. The diagnosis of treatment failure in many settings is challenging because of limited access to plasma HIV RNA testing. This article summarizes recent studies in LMICs, investigating the diagnosis of treatment failure.

RECENT FINDINGS

WHO recommended clinico-immunological criteria to identify first-line treatment failure, which have a low sensitivity and positive predictive value. The addition of adherence criteria or alternative clinical and laboratory markers improves performance, but overall the results are suboptimal. This situation leads to both delayed and inappropriately premature switching to more expensive second-line agents. The cost-effectiveness of alternative monitoring strategies is debated, but there is increasing interest in the use of viral load testing to confirm virological failure before switching to second-line therapy. However, access to viral load testing in LMICs remains limited and a simple point-of-care assay is not yet available.

SUMMARY

Monitoring the efficacy of antiretroviral therapy in LMICs remains a critical challenge. Current research priorities include the development of simpler, cheaper assays and optimizing monitoring strategies based on currently available technologies.

Antiretroviral medication adherence and the development of class-specific antiretroviral resistance

OBJECTIVE

To assess the association between antiretroviral adherence and the development of class-specific antiretroviral medication resistance.

DESIGN AND METHODS

Literature and conference abstract review of studies assessing the association between adherence to antiretroviral therapy and the development of antiretroviral medication resistance.

RESULTS

Factors that determine class-specific adherence-resistance relationships include antiretroviral regimen potency, viral fitness or, more specifically, the interplay between the fold-change in resistance and fold-change in fitness caused by drug resistance mutations, and the genetic barrier to antiretroviral resistance. During multidrug therapy, differential drug exposure increases the likelihood of developing resistance. In addition, antiretroviral medications with higher potency and higher genetic barriers to resistance decrease the incidence of resistance for companion antiretroviral medications at all adherence levels.

CONCLUSION

Knowledge of class-specific adherence-resistance relationships may help clinicians and patients tailor therapy to match individual patterns of adherence in order to minimize the development of resistance at failure. In addition, this information may guide the selection of optimal drug combinations and regimen sequences to improve the durability of antiretroviral therapy.