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

Point-of-care viral load monitoring: outcomes from a decentralized HIV programme in Malawi

Introduction

Routinely monitoring the HIV viral load (VL) of people living with HIV (PLHIV) on anti‐retroviral therapy (ART) facilitates intensive adherence counselling and faster ART regimen switch when treatment failure is indicated. Yet standard VL‐testing in centralized laboratories can be time‐intensive and logistically difficult in low‐resource settings. This paper evaluates the outcomes of the first four years of routine VL‐monitoring using Point‐of‐Care technology, implemented by Médecins Sans Frontières (MSF) in rural clinics in Malawi.

Methods

We conducted a retrospective cohort analysis of patients eligible for routine VL‐ testing between 2013 and 2017 in four decentralized ART‐clinics and the district hospital in Chiradzulu, Malawi. We assessed VL‐testing coverage and the treatment failure cascade (from suspected failure (first VL>1000 copies/mL) to VL suppression post regimen switch). We used descriptive statistics and multivariate logistic regression to assess factors associated with suspected failure.

Results and Discussion

Among 21,400 eligible patients, VL‐testing coverage was 85% and VL suppression was found in 89% of those tested. In the decentralized clinics, 88% of test results were reviewed on the same day as blood collection, whereas in the district hospital the median turnaround‐time for results was 85 days. Among first‐line ART patients with suspected failure (N = 1544), 30% suppressed (VL<1000 copies/mL), 35% were treatment failures (confirmed by subsequent VL‐testing) and 35% had incomplete VL follow‐up. Among treatment failures, 80% (N = 540) were switched to a second‐line regimen, with a higher switching rate in the decentralized clinics than in the district hospital (86% vs. 67%, p < 0.01) and a shorter median time‐to‐switch (6.8 months vs. 9.7 months, p < 0.01). Similarly, the post‐switch VL‐testing rate was markedly higher in the decentralized clinics (61% vs. 26%, p < 0.01). Overall, 79% of patients with a post‐switch VL‐test were suppressed.

Conclusions

Viral load testing at the point‐of‐care in Chiradzulu, Malawi achieved high coverage and good drug regimen switch rates among those identified as treatment failures. In decentralized clinics, same‐day test results and shorter time‐to‐switch illustrated the game‐changing potential of POC‐based VL‐testing. Nevertheless, gaps were identified along all steps of the failure cascade. Regular staff training, continuous monitoring and creating demand are essential to the success of routine VL‐testing.

Adoption of routine virologic testing and predictors of virologic failure among HIV-infected children on antiretroviral treatment in western Kenya

BACKGROUND

Access to routine virologic monitoring, critical to ensuring treatment success, remains limited in low- and middle-income countries. We report on implementation of routine viral load (VL) monitoring and risk factors for virologic failure among HIV-infected children on antiretroviral treatment (ART) in Western Kenya.

METHODS

Routine VL testing was introduced in western Kenya in November 2013. We performed a case-control study among 1190 HIV-infected children ≤15 years on ART who underwent routine VL testing June 2014-May 2015. A random sample of 98 cases (virologic failure define as VL >1000 cps/mL) and 201 controls (VL <1000 cps/mL) from five facilities in three high HIV prevalence counties in Kenya were followed for a minimum of 12 months. Data from patient charts were analyzed using logistic regression to determine factors associated with failure to attain virologic suppression at initial routine and subsequent VL testing among cases.

RESULTS

Overall, 1190 (94%) children with a median age of 8 years underwent routine VL testing of whom (37%) had virological failure. Among the 299 cases and controls, WHO stage, baseline CD4 count and time since ART initiation were not associated with virologic failure during the follow-up period. In multivariable analysis, unsuppressed children at initial test were more likely to be male (adjusted Odds Ratio (aOR) 2.1, 95% Confidence Interval (CI) 2.1-3.6) and have had an ART regimen change (aOR 2.0, CI 1.0-3.7) than controls. Of the two-thirds of children 201/299 who had a subsequent VL performed, VL suppression was greater among those suppressed at initial test 126/135 (93.3%) compared to children with virologic failure 15/66 (22.7%, p<0.0001). Among those failing at first test who achieved viral suppression in follow up, 12/15 (80%) were on a protease inhibitor (PI)-based regimen. In the multivariable analysis of children with subsequent VL testing, children on PI-based 2nd line regimens were 10-fold more likely to achieve viral suppression than children on first-line NNRTI-based ART (adjusted Odds Ratio [aOR] 0.1; 95%CI 0.0-0.4).

CONCLUSION

Coverage of initial routine viral load testing among children on ART in western Kenya is high. However, subsequent testing and virologic suppression are low in children with virologic failure on initial routine viral load test. There is an urgent need to improve management and viral load monitoring of children living with HIV experiencing treatment failure to ensure improved long-term outcomes.

Clinical Benefits and Cost-Effectiveness of Laboratory Monitoring Strategies to Guide Antiretroviral Treatment Switching in India

Current Indian guidelines recommend twice-annual CD4 testing to monitor first-line antiretroviral therapy (ART), with a plasma HIV RNA test to confirm failure if CD4 declines, which would prompt a switch to second-line ART. We used a mathematical model to assess the clinical benefits and cost-effectiveness of alternative laboratory monitoring strategies in India. We simulated a cohort of HIV-infected patients initiating first-line ART and compared 11 strategies with combinations of CD4 and HIV RNA testing at varying frequencies. We included adaptive strategies that reduce the frequency of tests after 1 year from 6 to 12 months for virologically suppressed patients. We projected life expectancy, time on failed first-line ART, cumulative 10-year HIV transmissions, lifetime cost (2014 US dollars), and incremental cost-effectiveness ratios (ICERs). We defined strategies as cost-effective if their ICER was <1 × the Indian per capita gross domestic product (GDP, $1,600). We found that the current Indian guidelines resulted in a per person life expectancy (from mean age 37) of 150.2 months and a per person cost of $2,680. Adding annual HIV RNA testing increased survival by ∼8 months; adaptive strategies were less expensive than similar nonadaptive strategies with similar life expectancy. The most effective strategy with an ICER <1 × GDP was the adaptive HIV RNA strategy (ICER $840/year). Cumulative 10-year transmissions decreased from 27.2/1,000 person-years with standard-of-care to 20.9/1,000 person-years with adaptive HIV RNA testing. In India, routine HIV RNA monitoring of patients on first-line ART would increase life expectancy, decrease transmissions, be cost-effective, and should be implemented.

Assessment of WHO criteria for identifying ART treatment failure in Vietnam from 2007 to 2011

Objective

We evaluated the sensitivity and specificity of the WHO immunological criteria for detecting antiretroviral therapy (ART) treatment failure in a cohort of Vietnamese patients. We conducted a stratified analysis to determine the effects of BMI, peer support, adherence to antiretroviral (ARV) drugs, age, and gender on the sensitivity and specificity of the WHO criteria.

Methods

We conducted a retrospective cohort study of 605 HIV-infected patients using data previously collected from a cluster randomized control trial study. We compared the sensitivity and specificity of CD4⁺ counts to the gold standard of virologic testing as a diagnostic test for ART failure at different time points of 12, 18, and 24 months.

Results

The sensitivity [95% confidence interval (CI)] of the WHO immunological criteria based on a viral load ≥ 1000 copies/mL was 12% (5%-23%), 14% (2%-43%), and 12.5% (2%-38%) at 12, 18, and 24 months, respectively. In the same order, the specificity was 93% (90%-96%), 98% (96%-99%), and 98% (96%-100%). The positive predictive values (PPV) at 12, 18, and 24 months were 22% (9%-40%), 20% (3%-56%), and 29% (4%-71%); the negative predictive values (NPV) at the same time points were 87% (84%-90%), 97% (95%-98%), and 96% (93%-98%). The stratified analysis revealed similar sensitivities and specificities.

Conclusion

The sensitivity of the WHO immunological criteria is poor, but the specificity is high. Although testing costs may increase, we recommend that Vietnam and other similar settings adopt viral load testing as the principal method for determining ART failure.

Positive Predictive Value of the WHO Clinical and Immunologic Criteria to Predict Viral Load Failure among Adults on First, or Second-Line Antiretroviral Therapy in Kenya

Routine HIV viral load (VL) monitoring is the standard of care for persons receiving antiretroviral therapy (ART) in developed countries. Although the World Health Organization recommends annual VL monitoring of patients on ART, recognizing difficulties in conducting routine VL testing, the WHO continues to recommend targeted VL testing to confirm treatment failure for persons who meet selected immunologic and clinical criteria. Studies have measured positive predictive value (PPV), negative predictive value, sensitivity and specificity of these criteria among patients receiving first-line ART but not specifically among those on second-line or subsequent regimens. Between 2008 and 2011, adult ART patients in Nyanza, Kenya who met national clinical or immunologic criteria for treatment failure received targeted VL testing. We calculated PPV and 95% confidence intervals (CI) of these criteria to detect virologic treatment failure among patients receiving a) first-line ART, b) second/subsequent ART, and c) any regimen. Of 12,134 patient specimens tested, 2,874 (23.7%) were virologically confirmed as treatment failures. The PPV for 2,834 first-line ART patients who met either the clinical or immunologic criteria for treatment failure was 34.4% (95% CI 33.2–35.7), 33.1% (95% CI 24.7–42.3) for the 40 patients on second-line/subsequent regimens, and 33.4% (95% CI 33.1–35.6) for any ART. PPV, regardless of criteria, for first-line ART patients was lowest among patients over 44 years old and highest for patients aged 15 to 34 years. PPV of immunological and clinical criteria for correctly identifying treatment failure was similarly low for adult patients receiving either first-line or second-line/subsequent ART regimens. Our data confirm the inadequacy of clinical and immunologic criteria to correctly identify treatment failure and support the implementation of routine VL testing.

Economic and epidemiological impact of early antiretroviral therapy initiation in India

Introduction

Recent WHO guidance advocates for early antiretroviral therapy (ART) initiation at higher CD4 counts to improve survival and reduce HIV transmission. We sought to quantify how the cost-effectiveness and epidemiological impact of early ART strategies in India are affected by attrition throughout the HIV care continuum.

Methods

We constructed a dynamic compartmental model replicating HIV transmission, disease progression and health system engagement among Indian adults. Our model of the Indian HIV epidemic compared implementation of early ART initiation (i.e. initiation above CD4 ≥350 cells/mm³) with delayed initiation at CD4 ≤350 cells/mm³; primary outcomes were incident cases, deaths, quality-adjusted-life-years (QALYs) and costs over 20 years. We assessed how costs and effects of early ART initiation were impacted by suboptimal engagement at each stage in the HIV care continuum.

Results

Assuming “idealistic” engagement in HIV care, early ART initiation is highly cost-effective ($442/QALY-gained) compared to delayed initiation at CD4 ≤350 cells/mm³ and could reduce new HIV infections to <15,000 per year within 20 years. However, when accounting for realistic gaps in care, early ART initiation loses nearly half of potential epidemiological benefits and is less cost-effective ($530/QALY-gained). We project 1,285,000 new HIV infections and 973,000 AIDS-related deaths with deferred ART initiation with current levels of care-engagement in India. Early ART initiation in this continuum resulted in 1,050,000 new HIV infections and 883,000 AIDS-related deaths, or 18% and 9% reductions (respectively), compared to current guidelines. Strengthening HIV screening increases benefits of earlier treatment modestly (1,001,000 new infections; 22% reduction), while improving retention in care has a larger modulatory impact (676,000 new infections; 47% reduction).

Conclusions

Early ART initiation is highly cost-effective in India but only has modest epidemiological benefits at current levels of care-engagement. Improved retention in care is needed to realize the full potential of earlier treatment.

On the front line of HIV virological monitoring: barriers and facilitators from a provider perspective in resource-limited settings

Scale-up of viral load (VL) monitoring for HIV-infected patients on antiretroviral therapy (ART) is a priority in many resource-limited settings, and ART providers are critical to effective program implementation. We explored provider-perceived barriers and facilitators of VL monitoring. We interviewed all providers (n = 17) engaged in a public health evaluation of dried blood spots for VL monitoring at five ART clinics in Malawi. All ART clinics were housed within district hospitals. We grouped themes at patient, provider, facility, system, and policy levels. Providers emphasized their desire for improved ART monitoring strategies, and frustration in response to restrictive policies for determining which patients were eligible to receive VL monitoring. Although many providers pled for expansion of monitoring to include all persons on ART, regardless of time on ART, the most salient provider-perceived barrier to VL monitoring implementation was the pressure of work associated with monitoring activities. The work burden was exacerbated by inefficient data management systems, highlighting a critical interaction between provider-, facility-, and system-level factors. Lack of integration between laboratory and clinical systems complicated the process for alerting providers when results were available, and these communication gaps were intensified by poor facility connectivity. Centralized second-line ART distribution was also noted as a barrier: providers reported that the time and expenses required for patients to collect second-line ART frequently obstructed referral. However, provider empowerment emerged as an unexpected facilitator of VL monitoring. For many providers, this was the first time they used an objective marker of ART response to guide clinical management. Providers' knowledge of a patient's virological status increased confidence in adherence counseling and clinical decision-making. Results from our study provide unique insight into provider perceptions of VL monitoring and indicate the importance of policies responsive to individual and environmental challenges of VL monitoring program implementation. Findings may inform scale-up by helping policy-makers identify strategies to improve feasibility and sustainability of VL monitoring.

Immunological failure of first-line and switch to second-line antiretroviral therapy among HIV-infected persons in Tanzania: analysis of routinely collected national data

OBJECTIVES

Rates of first-line treatment failure and switches to second-line therapy are key indicators for national HIV programmes. We assessed immunological treatment failure defined by WHO criteria in the Tanzanian national HIV programme.

METHODS

We included adults initiating first-line therapy in 2004-2011 with a pre-treatment CD4 count, and ≥6-months of follow-up. We assessed subhazard ratios (SHR) for immunological treatment failure, and subsequent switch to second-line therapy, using competing risks methods to account for deaths.

RESULTS

Of 121 308 adults, 7% experienced immunological treatment failure, and 2% died without observed immunological treatment failure, over a median 1.7 years. The 6-year cumulative probability of immunological treatment failure was 19.0% (95% CI 18.5, 19.7) and of death, 5.1% (4.8, 5.4). Immunological treatment failure predictors included earlier year of treatment initiation (P < 0.001), initiation in lower level facilities (SHR = 2.23 [2.03, 2.45] for dispensaries vs. hospitals), being male (1.27 [1.19, 1.33]) and initiation at low or high CD4 counts (for example, 1.78 [1.65, 1.92] and 5.33 [4.65, 6.10] for <50 and ≥500 vs. 200-349 cells/mm(3) , respectively). Of 7382 participants in the time-to-switch analysis, 6% switched and 5% died before switching. Four years after immunological treatment failure, the cumulative probability of switching was 7.3% (6.6, 8.0) and of death, 6.8% (6.0, 7.6). Those who immunologically failed in dispensaries, health centres and government facilities were least likely to switch.

CONCLUSIONS

Immunological treatment failure rates and unmet need for second-line therapy are high in Tanzania; virological monitoring, at least for persons with immunological treatment failure, is required to minimise unnecessary switches to second-line therapy. Lower level government health facilities need more support to reduce treatment failure rates and improve second-line therapy uptake to sustain the benefits of increased coverage.

Predictors of immunological failure and determinants of suboptimal CD4 testing among adults with HIV on first-line antiretroviral therapy in Andhra Pradesh, India, 2008-2011

BACKGROUND

Failure of first-line antiretroviral therapy (ART) results in high morbidity and mortality. We identified the predictors of immunological failure and suboptimal CD4 testing among adult people living with HIV (PLHIV) initiated on first-line ART.

METHODS

The cohort of PLHIV aged ≥ 15 years initiated on first-line ART in Hyderabad city, Andhra Pradesh state, in 2008 was followed-up until 31 December 2011 or until death and/or lost to follow-up (LFU). We estimated cumulative incidence of immunological failure. We explored socio-demographic, clinical, pharmacological and immunological factors to identify the predictors of immunological failure and determinants of suboptimal CD4 testing (<2 tests/year).

RESULTS

Among the 1431 PLHIV, 275 (19.2%) died and 263 (18.4%) were LFU. Of the remaining 893 (62.3%) patients on follow-up, 193 (21.6%) experienced immunological failure; these patients were more likely to be males, illiterate, with a history of pulmonary TB while on ART and taking stavudine-based regimen. Incidence of suboptimal testing ranged between 41 and 60% over 4 years of follow-up. Suboptimal CD4 testing among PLHIV was associated with history of TB prior to initiation of ART and stage 3 and 4 of HIV disease at enrollment.

CONCLUSIONS

There was low immunological failure rate but high incidence of suboptimal CD4 testing. The ART centre staff needs to be more vigilant about 6-monthly CD4 testing for timely detection of immunological failure and appropriate case management.

Determinants of virological failure after 1 year's antiretroviral therapy in Vietnamese people with HIV: findings from a retrospective cohort of 13 outpatient clinics in six provinces

OBJECTIVE

This study examines the proportions and causes of virological failure after one year of antiretroviral therapy (ART) among people living with HIV (PLHIV) in Vietnam. It also evaluates the positive predictive value (PPV) of immunological criteria to detect treatment failure.

METHOD

A retrospective cohort of 3449 people with HIV who started ART between 1 January 2005 and 31 December 2009 in 13 outpatient clinics in Vietnam was studied. Multivariate logistic regression modeling was used to calculate crude and adjusted ORs and 95% CIs for associations between patient characteristics and virological failure.

RESULTS

An estimated 6.5% (226/3449) of HIV patients in the participating clinics in Vietnam had confirmed virological failure one year after the start of ART. After adjusting for other factors, patients with a baseline CD4 count of 50-100 cells/mm(3) and 101-200 cells/mm(3) were statistically significantly less likely to have virological failure, compared to those with a baseline CD4 count lower than 50 cells/mm(3) (OR=0.61, 95% CI 0.23-0.89; and OR=0.43, 0.18-0.78, respectively). In contrast, patients with a history of injecting drug use were statistically significantly more likely to have viraemia than otherwise (OR=1.32, 1.16-1.67). The PPV of the WHO immunological criteria was 60.1% (57.1-69.3%).

CONCLUSIONS

Routine viral load tests should be conducted early to detect virological failure and prevent unnecessary changes to second-line treatments. To improve treatment outcomes, timely ART initiation and adherence to treatment among those with history of injecting drug use should be promoted.

Patterns of adherence to antiretroviral therapy and HIV drug resistance over time in the Stratall ANRS 12110/ESTHER trial in Cameroon

OBJECTIVES

The emergence of HIV drug resistance is a crucial issue in Africa, where second-line antiretroviral therapy (ART) is limited, expensive and complex. We assessed the association between adherence patterns and resistance emergence over time, using an adherence measure that distinguishes low adherence from treatment interruptions, in rural Cameroon.

METHODS

We performed a cohort study among patients receiving nonnucleoside reverse transcriptase inhibitor (NNRTI)-based ART in nine district hospitals, using data from the Stratall trial (2006-2010). Genotypic mutations associated with antiretroviral drug resistance were assessed when 6-monthly HIV viral loads were > 5000 HIV-1 RNA copies/mL. ART adherence data were collected using face-to-face questionnaires. Combined indicators of early (1-3 months) and late (6 months to t - 1; t is the time point when the resistance had been detected) adherence were constructed. Multivariate logistic regression and Cox models were used to assess the association between adherence patterns and early (at 6 months) and late (after 6 months) resistance emergence, respectively.

RESULTS

Among 456 participants (71% women; median age 37 years), 45 developed HIV drug resistance (18 early and 27 late). Early low adherence (< 80%) and treatment interruptions (> 2 days) were associated with early resistance [adjusted odds ratio (95% confidence interval) 8.51 (1.30-55.61) and 5.25 (1.45-18.95), respectively]. Early treatment interruptions were also associated with late resistance [adjusted hazard ratio (95% confidence interval) 3.72 (1.27-10.92)].

CONCLUSIONS

The emergence of HIV drug resistance on first-line NNRTI-based regimens was associated with different patterns of adherence over time. Ensuring optimal early adherence through specific interventions, adequate management of drug stocks, and viral load monitoring is a clinical and public health priority in Africa.

Predicting treatment failure in adults and children on antiretroviral therapy: a systematic review of the performance characteristics of the 2010 WHO immunologic and clinical criteria for virologic failure

OBJECTIVE

We systematically reviewed the performance of 2010 WHO immunologic and clinical criteria for predicting virologic failure in HIV-infected patients on antiretroviral therapy (ART).

DESIGN

Systematic review.

METHODS

We used Cochrane Collaboration methods. We calculated unweighted sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of immunologic and clinical criteria for predicting virologic failure.

RESULTS

We identified 18 studies. Sixteen assessed immunologic criteria in adults; 12 defined virologic failure as a plasma viral load of more than 50 to more than 1000 copies/ml in adults, three as viral load at least 5000 copies/ml, and two as viral load more than 10,000 copies/ml; the sensitivity ranged from 16.8 to 54.9%, specificity from 82.9 to 95.5%, PPV from 15.0 to 38.8%, and NPV from 90.9 to 98.6%. Seven studies assessed clinical criteria to predict viral load of more than 50 to more than 1000 copies/ml; the sensitivity was 11.0%, specificity 90.5%, PPV 44.9%, and NPV 90.2%. Seven studies assessed clinical or immunologic criteria defining virologic failure as viral load of more than 50 to more than 1000 copies/ml; their sensitivity was 26.6%, specificity 85.9%, PPV 49.4%, and NPV 91.1%. Four studies assessed immunologic criteria in children; three defined virologic failure as viral load at least 5000 copies/ml and one as viral load at least 400 copies/ml. The sensitivity ranged from 4.5 to 6.3%, specificity from 97.7 to 99.3%, PPV from 20.0 to 54.9%, and NPV from 85.5 to 91.8%.

CONCLUSION

The 2010 WHO clinical and immunologic criteria are insensitive and have low PPV for predicting virologic failure. These data support the strong recommendation 2013 treatment guidelines that viral load testing be used to monitor for, diagnose, and confirm ART failure.

HIV-1 Genetic Variability and Clinical Implications

Despite advances in antiretroviral therapy that have revolutionized HIV disease management, effective control of the HIV infection pandemic remains elusive. Beyond the classic non-B endemic areas, HIV-1 non-B subtype infections are sharply increasing in previous subtype B homogeneous areas such as Europe and North America. As already known, several studies have shown that, among non-B subtypes, subtypes C and D were found to be more aggressive in terms of disease progression. Luckily, the response to antiretrovirals against HIV-1 seems to be similar among different subtypes, but these results are mainly based on small or poorly designed studies. On the other hand, differences in rates of acquisition of resistance among non-B subtypes are already being observed. This different propensity, beyond the type of treatment regimens used, as well as access to viral load testing in non-B endemic areas seems to be due to HIV-1 clade specific peculiarities. Indeed, some non-B subtypes are proved to be more prone to develop resistance compared to B subtype. This phenomenon can be related to the presence of subtype-specific polymorphisms, different codon usage, and/or subtype-specific RNA templates. This review aims to provide a complete picture of HIV-1 genetic diversity and its implications for HIV-1 disease spread, effectiveness of therapies, and drug resistance development.

Evaluation of WHO immunologic criteria for treatment failure: implications for detection of virologic failure, evolution of drug resistance and choice of second-line therapy in India

Introduction

Routine HIV viral load (VL) testing is not available in India. We compared test performance characteristics of immunologic failure (IF) against the gold standard of virologic failure (VF), examined evolution of drug resistance among those who stayed on a failing regimen because they did not meet criteria for IF and assessed implications for second-line therapy.

Methods

Participants on first-line highly active antiretroviral therapy (HAART) in Bangalore, India, were monitored for 24 months at six-month intervals, with CD4 count, VL and genotype, if VL>1000 copies/ml. Standard WHO criteria were used to define IF; VF was defined as having two consecutive VL>1000 copies/ml or one VL>10,000 copies/ml. Resistance was assessed using standard International AIDS Society-USA (IAS-USA) recommendations.

Results

Of 522 participants (67.6% male, mean age of 37.5; 85.1% on nevirapine-based and 40.4% on d4T-containing regimens), 57 (10.9%) had VF, 38 (7.3%) had IF and 13 (2.5%) had both VF and IF. The sensitivity of immunologic criteria to detect VF was 22.8%, specificity was 94.6% and positive predictive value was 34.2%. Forty-four participants with VF only continued on their failing first-line regimen; by the end of the study period, 90.9% had M184V, 63.6% had thymidine analogue mutations (TAMs), 34.1% had resistance to tenofovir, and 63.6% had resistance to etravirine.

Conclusions

WHO IF criteria have low sensitivity for detecting VF, and the presence of IF poorly predicts VF. Relying on CD4 counts leads to unnecessary switches to second-line HAART and continuation of failing regimens, jeopardizing future therapeutic options. Universal access to VL monitoring would avoid costly switches to second-line HAART and preserve future treatment options.

Challenges and opportunities for the implementation of virological testing in resource-limited settings

Though the advantages of routine virological monitoring for patients on anti-retroviral therapy have been established, cost and complexity limit its full implementation. Monitoring is important for diagnosing virological failure early on, before the development of drug resistance mutations, and to trigger early adherence interventions. Simple and cost-effective viral load tests that facilitate simplification and decentralization of testing and strategies, such as the use of dried blood spots and pooled sample testing, which further aid simplification, are becoming available. In addition, replacing immunological monitoring with virological monitoring in non-viremic patients in a phased manner will reduce the costs associated with dual immuno-virological monitoring. Going forward, the simplification of testing paired with price reducing strategies that will allow for healthy competition between multiple manufacturers will enable the implementation of viral load testing in resource-poor settings. It is important that future HIV and AIDS treatment guidelines provide clear recommendations for routine virological monitoring and that governments and donors fund the implementation of accurate and operationally proven testing platforms in a comprehensive manner.

The role of targeted viral load testing in diagnosing virological failure in children on antiretroviral therapy with immunological failure

OBJECTIVES

To determine the improvement in positive predictive value of immunological failure criteria for identifying virological failure in HIV-infected children on antiretroviral therapy (ART) when a single targeted viral load measurement is performed in children identified as having immunological failure.

METHODS

Analysis of data from children (<16 years at ART initiation) at South African ART sites at which CD4 count/per cent and HIV-RNA monitoring are performed 6-monthly. Immunological failure was defined according to both WHO 2010 and United States Department of Health and Human Services (DHHS) 2008 criteria. Confirmed virological failure was defined as HIV-RNA >5000 copies/ml on two consecutive occasions <365 days apart in a child on ART for ≥18 months.

RESULTS

Among 2798 children on ART for ≥18 months [median (IQR) age 50 (21-84) months at ART initiation], the cumulative probability of confirmed virological failure by 42 months on ART was 6.3%. Using targeted viral load after meeting DHHS immunological failure criteria rather than DHHS immunological failure criteria alone increased positive predictive value from 28% to 82%. Targeted viral load improved the positive predictive value of WHO 2010 criteria for identifying confirmed virological failure from 49% to 82%.

CONCLUSION

The addition of a single viral load measurement in children identified as failing immunologically will prevent most switches to second-line treatment in virologically suppressed children.

Adherence to drug-refill is a useful early warning indicator of virologic and immunologic failure among HIV patients on first-line ART in South Africa

BACKGROUND

Affordable strategies to prevent treatment failure on first-line regimens among HIV patients are essential for the long-term success of antiretroviral therapy (ART) in sub-Saharan Africa. WHO recommends using routinely collected data such as adherence to drug-refill visits as early warning indicators. We examined the association between adherence to drug-refill visits and long-term virologic and immunologic failure among non-nucleoside reverse transcriptase inhibitor (NNRTI) recipients in South Africa.

METHODS

In 2008, 456 patients on NNRTI-based ART for a median of 44 months (range 12-99 months; 1,510 person-years) were enrolled in a retrospective cohort study in Soweto. Charts were reviewed for clinical characteristics before and during ART. Multivariable logistic regression and Kaplan-Meier survival analysis assessed associations with virologic (two repeated VL>50 copies/ml) and immunologic failure (as defined by WHO).

RESULTS

After a median of 15 months on ART, 19% (n = 88) and 19% (n = 87) had failed virologically and immunologically respectively. A cumulative adherence of <95% to drug-refill visits was significantly associated with both virologic and immunologic failure (p<0.01). In the final multivariable model, risk factors for virologic failure were incomplete adherence (OR 2.8, 95%CI 1.2-6.7), and previous exposure to single-dose nevirapine or any other antiretrovirals (adj. OR 2.1, 95%CI 1.2-3.9), adjusted for age and sex. In Kaplan-Meier analysis, the virologic failure rate by month 48 was 19% vs. 37% among adherent and non-adherent patients respectively (logrank p value = 0.02).

CONCLUSION

One in five failed virologically after a median of 15 months on ART. Adherence to drug-refill visits works as an early warning indicator for both virologic and immunologic failure.