HIV drug resistance surveillance for prioritizing treatment in resource-limited settings

Effectiveness and cost-effectiveness of potential responses to future high levels of transmitted HIV drug resistance in antiretroviral drug-naive populations beginning treatment: modelling study and economic analysis

BACKGROUND

With continued roll-out of antiretroviral therapy (ART) in resource-limited settings, evidence is emerging of increasing levels of transmitted drug-resistant HIV. We aimed to compare the effectiveness and cost-effectiveness of different potential public health responses to substantial levels of transmitted drug resistance.

METHODS

We created a model of HIV transmission, progression, and the effects of ART, which accounted for resistance generation, transmission, and disappearance of resistance from majority virus in the absence of drug pressure. We simulated 5000 ART programmatic scenarios with different prevalence levels of detectable resistance in people starting ART in 2017 (t0) who had not previously been exposed to antiretroviral drugs. We used the model to predict cost-effectiveness of various potential changes in policy triggered by different prevalence levels of resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) measured in the population starting ART.

FINDINGS

Individual-level resistance testing before ART initiation was not generally a cost-effective option, irrespective of the cost-effectiveness threshold. At a cost-effectiveness threshold of US$500 per quality-adjusted life-year (QALY), no change in policy was cost effective (ie, no change in policy would involve paying less than $500 per QALY gained), irrespective of the prevalence of pretreatment NNRTI resistance, because of the increased cost of the policy alternatives. At thresholds of $1000 or higher, and with the prevalence of pretreatment NNRTI resistance greater than 10%, a policy to measure viral load 6 months after ART initiation became cost effective. The policy option to change the standard first-line treatment to a boosted protease inhibitor regimen became cost effective at a prevalence of NNRTI resistance higher than 15%, for cost-effectiveness thresholds greater than $2000.

INTERPRETATION

Cost-effectiveness of potential policies to adopt in response to different levels of pretreatment HIV drug resistance depends on competing budgetary claims, reflected in the cost-effectiveness threshold. Results from our model will help inform WHO recommendations on monitoring of HIV drug resistance in people starting ART.

FUNDING

WHO (with funds provided by the Bill & Melinda Gates Foundation), CHAIN (European Commission).

Cost-effectiveness of HIV drug resistance testing to inform switching to second line antiretroviral therapy in low income settings

Background

To guide future need for cheap resistance tests for use in low income settings, we assessed cost-effectiveness of drug resistance testing as part of monitoring of people on first line ART - with switching from first to second line ART being conditional on NNRTI drug resistance mutations being identified.

Methods

An individual level simulation model of HIV transmission, progression and the effect of ART which accounts for adherence and resistance development was used to compare outcomes of various potential monitoring strategies in a typical low income setting in sub-Saharan Africa. Underlying monitoring strategies considered were based on clinical disease, CD4 count or viral load. Within each we considered a strategy in which no further measures are performed, one with a viral load measure to confirm failure, and one with both a viral load measure and a resistance test. Predicted outcomes were assessed over 2015–2025 in terms of viral suppression, first line failure, switching to second line regimen, death, HIV incidence, disability-adjusted-life-years averted and costs. Potential future low costs of resistance tests ($30) were used.

Results

The most effective strategy, in terms of DALYs averted, was one using viral load monitoring without confirmation. The incremental cost-effectiveness ratio for this strategy was $2113 (the same as that for viral load monitoring with confirmation). ART monitoring strategies which involved resistance testing did not emerge as being more effective or cost effective than strategies not using it. The slightly reduced ART costs resulting from use of resistance testing, due to less use of second line regimens, was of similar magnitude to the costs of resistance tests.

Conclusion

Use of resistance testing at the time of first line failure as part of the decision whether to switch to second line therapy was not cost-effective, even though the test was assumed to be very inexpensive.

Patient- and population-level health consequences of discontinuing antiretroviral therapy in settings with inadequate HIV treatment availability

Background

In resource-limited settings, HIV budgets are flattening or decreasing. A policy of discontinuing antiretroviral therapy (ART) after HIV treatment failure was modeled to highlight trade-offs among competing policy goals of optimizing individual and population health outcomes.

Methods

In settings with two available ART regimens, we assessed two strategies: (1) continue ART after second-line failure (Status Quo) and (2) discontinue ART after second-line failure (Alternative). A computer model simulated outcomes for a single cohort of newly detected, HIV-infected individuals. Projections were fed into a population-level model allowing multiple cohorts to compete for ART with constraints on treatment capacity. In the Alternative strategy, discontinuation of second-line ART occurred upon detection of antiretroviral failure, specified by WHO guidelines. Those discontinuing failed ART experienced an increased risk of AIDS-related mortality compared to those continuing ART.

Results

At the population level, the Alternative strategy increased the mean number initiating ART annually by 1,100 individuals (+18.7%) to 6,980 compared to the Status Quo. More individuals initiating ART under the Alternative strategy increased total life-years by 15,000 (+2.8%) to 555,000, compared to the Status Quo. Although more individuals received treatment under the Alternative strategy, life expectancy for those treated decreased by 0.7 years (−8.0%) to 8.1 years compared to the Status Quo. In a cohort of treated patients only, 600 more individuals (+27.1%) died by 5 years under the Alternative strategy compared to the Status Quo. Results were sensitive to the timing of detection of ART failure, number of ART regimens, and treatment capacity. Although we believe the results robust in the short-term, this analysis reflects settings where HIV case detection occurs late in the disease course and treatment capacity and the incidence of newly detected patients are stable.

Conclusions

In settings with inadequate HIV treatment availability, trade-offs emerge between maximizing outcomes for individual patients already on treatment and ensuring access to treatment for all people who may benefit. While individuals may derive some benefit from ART even after virologic failure, the aggregate public health benefit is maximized by providing effective therapy to the greatest number of people. These trade-offs should be explicit and transparent in antiretroviral policy decisions.

Cost-effectiveness of the third-agent class in treatment-naive human immunodeficiency virus-infected patients in Portugal

INTRODUCTION

Current Portuguese HIV treatment guidelines recommend initiating antiretroviral therapy with a regimen composed of two Nucleoside Reverse Transcriptase Inhibitors plus one Non-nucleoside Reverse Transcriptase Inhibitor (2NRTI+NNRTI) or two Nucleoside Reverse Transcriptase Inhibitors plus one boosted protease inhibitor (2NRTI+PI/r). Given the lower daily cost of NNRTI as the third agent when compared to the average daily costs of PI/r, it is relevant to estimate the long term impact of each treatment option in the Portuguese context.

METHODS

We developed a microsimulation discrete events model for cost-effectiveness analysis of HIV treatment, simulating individual paths from ART initiation to death. Four driving forces determine the course of events: CD4+ cell count, viral load, resistance and adherence. Distributions of time to event are conditional to individuals' characteristics and past history. Time to event was modeled using parametric survival analysis using Stata 11®. Disease progression was structured according to therapy lines and the model was parameterized with cohort Portuguese observational data. All resources were valued at 2009 prices. The National Health Service's perspective was assumed considering a lifetime horizon and a 5% annual discount rate.

RESULTS

In this analysis, initiating therapy with two Nucleoside Reverse Transcriptase Inhibitors plus one Non-nucleoside Reverse Transcriptase Inhibitor reduces the average number of switches by 17%, saves 19.573€ per individual and increases life expectancy by 1.7 months showing to be a dominant strategy in 57% of the simulations when compared to two Nucleoside Reverse Transcriptase Inhibitors plus one boosted protease inhibitor.

CONCLUSION

This study suggests that, when clinically valid, initiating therapy with two Nucleoside Reverse Transcriptase Inhibitors plus one Non-nucleoside Reverse Transcriptase Inhibitor is a cost-saving strategy and equally effective when compared to two Nucleoside Reverse Transcriptase Inhibitors plus one boosted protease inhibitor as the first regimen.

A literature review of reporting standards of HIV progression models

OBJECTIVE

We conducted a systematic review of HIV progression models to identify the mathematical structures used, the main research questions and key model aspects in terms of quality and robustness.

METHODS

We searched for articles published before February 2009 that described models of HIV progression in humans. We included two strategies of search with and without MeSH terms. We classified the models by their mathematical structure and research question. We created a checklist of desirable features of the models, reviewed and classified the articles to inform our conclusions.

RESULTS

Among 3491 articles found, 93 met the inclusion criteria. Among the selected articles, 60 used transition models, 25 applied differential equations, and eight had other structures. We did not find a relation between the type of question explored and the modeling method used. None of the studies complied with the complete set of items in the checklist, but 6.5% cover at least 90% of them.

CONCLUSION

There is an enormous heterogeneity of HIV modeling exercises in terms of methods used and topics addressed, as well as in the presentation of key aspects of the articles in terms of quality and robustness.

What do mathematical models tell us about the emergence and spread of drug-resistant HIV?

PURPOSE OF REVIEW

To discuss recent HIV epidemic models examining the transmission of antiretroviral (ARV) drug resistance.

RECENT FINDINGS

A relatively small number of recent transmission models have investigated ARV resistance in the context of therapeutic, combined ART (cART); ARV-vaginal microbicides (ARV-VMB); and oral pre-exposure prophylaxis (PrEP). Models of cART use have highlighted potential concerns about future resistance transmission, particularly in resource-constrained settings, and have emphasized the benefits of viral load monitoring in limiting resistance spread. PrEP models have concluded that inadvertent use by HIV-infected individuals could increase resistance prevalence, and that risk compensation by PrEP users could limit their beneficial effects on HIV transmission. ARV-VMB models have demonstrated that whereas resistance can reduce prophylactic effectiveness in preventing HIV acquisition of female ARV-VMB users, it may concomitantly benefit users' male partners if the resistant strains that female users acquire are less transmissible than wild-type strains. The models have examined the balance between these two factors at the population level.

SUMMARY

Recent HIV transmission models have adopted a wide assortment of structures and assumptions to explore drug resistance in the context of different ARV interventions in various settings. There is a need for future work emphasizing the simultaneous effects of multiple ARV interventions, as well as the public health impact of resistance, not just its prevalence.

The clinical impact and cost-effectiveness of routine, voluntary HIV screening in South Africa

BACKGROUND

Although 900,000 HIV-infected South Africans receive antiretroviral therapy, the majority of South Africans with HIV remain undiagnosed.

METHODS

We use a published simulation model of HIV case detection and treatment to examine 3 HIV screening scenarios, in addition to current practice as follows: (1) one-time; (2) every 5 years; and (3) annually. South African model input data include the following: 16.9% HIV prevalence, 1.3% annual incidence, 49% test acceptance rate, HIV testing costs of $6.49/patient, and a 47% linkage-to-care rate (including 2 sequential antiretroviral therapy regimens) for identified cases. Outcomes include life expectancy, direct medical costs, and incremental cost-effectiveness.

RESULTS

HIV screening one-time, every 5 years, and annually increase HIV-infected quality-adjusted life expectancy (mean age 33 years) from 180.6 months (current practice) to 184.9, 187.6, and 197.2 months. The incremental cost-effectiveness of one-time screening is dominated by screening every 5 years. Screening every 5 years and annually each have incremental cost-effectiveness ratios of $1570/quality-adjusted life year and $1720/quality-adjusted life year. Screening annually is very cost-effective even in settings with the lowest incidence/prevalence, with test acceptance and linkage rates both as low as 20%, or when accounting for a stigma impact at least four-fold that of the base case.

CONCLUSIONS

In South Africa, annual voluntary HIV screening offers substantial clinical benefit and is very cost-effective, even with highly constrained access to care and treatment.

Antiretroviral therapy optimisation without genotype resistance testing: a perspective on treatment history based models

Background

Although genotypic resistance testing (GRT) is recommended to guide combination antiretroviral therapy (cART), funding and/or facilities to perform GRT may not be available in low to middle income countries. Since treatment history (TH) impacts response to subsequent therapy, we investigated a set of statistical learning models to optimise cART in the absence of GRT information.

Methods and Findings

The EuResist database was used to extract 8-week and 24-week treatment change episodes (TCE) with GRT and additional clinical, demographic and TH information. Random Forest (RF) classification was used to predict 8- and 24-week success, defined as undetectable HIV-1 RNA, comparing nested models including (i) GRT+TH and (ii) TH without GRT, using multiple cross-validation and area under the receiver operating characteristic curve (AUC). Virological success was achieved in 68.2% and 68.0% of TCE at 8- and 24-weeks (n = 2,831 and 2,579), respectively. RF (i) and (ii) showed comparable performances, with an average (st.dev.) AUC 0.77 (0.031) vs. 0.757 (0.035) at 8-weeks, 0.834 (0.027) vs. 0.821 (0.025) at 24-weeks. Sensitivity analyses, carried out on a data subset that included antiretroviral regimens commonly used in low to middle income countries, confirmed our findings. Training on subtype B and validation on non-B isolates resulted in a decline of performance for models (i) and (ii).

Conclusions

Treatment history-based RF prediction models are comparable to GRT-based for classification of virological outcome. These results may be relevant for therapy optimisation in areas where availability of GRT is limited. Further investigations are required in order to account for different demographics, subtypes and different therapy switching strategies.

Economic evaluation of ART in resource-limited countries

PURPOSE OF REVIEW

In the face of increasing economic constraints, it is critically important to evaluate how best to utilize available resources. In this article, we review the growing number of cost-effectiveness analyses of HIV treatment with antiretroviral therapy (ART) in resource-limited settings. We focus on studies that evaluate when to start therapy, what therapy to start with and what to switch to based on what criteria.

RECENT FINDINGS

Recent findings show that earlier ART initiation based on CD4 cell count criteria (CD4 cell counts <350 cells/microl) can be cost effective in most resource-limited settings. They also suggest that initiating ART with tenofovir as a component of the first-line regimen is an efficient use of resources compared with initiating ART with stavudine. Finally, they show that HIV RNA monitoring combined with CD4 monitoring is more effective than CD4 monitoring alone, although this strategy was not yet found to be cost effective in all studies. Nearly all studies demonstrate, however, that the cost-effectiveness ratio of HIV RNA monitoring will become more attractive as the cost of HIV RNA tests and second-line ART regimens decrease.

SUMMARY

Substantial research shows that ART for HIV disease in resource-limited settings is cost effective. Improved initial regimens and increased laboratory monitoring may provide both clinical benefit and good value for money. Further price reductions of laboratory tests and recent antiretroviral drugs are needed to guarantee the cost-effectiveness of these required improvements.

Laboratory monitoring to guide switching antiretroviral therapy in resource-limited settings: clinical benefits and cost-effectiveness

BACKGROUND

As second-line antiretroviral therapy (ART) availability increases in resource-limited settings, questions about the value of laboratory monitoring remain. We assessed the outcomes and cost-effectiveness (CE) of laboratory monitoring to guide switching ART.

METHODS

We used a computer model to project life expectancy and costs of different strategies to guide ART switching in patients in Côte d'Ivoire. Strategies included clinical assessment, CD4 count, and HIV RNA testing. Data were from clinical trials and cohort studies from Côte d'Ivoire and the literature. Outcomes were compared using the incremental CE ratio. We conducted multiple sensitivity analyses to assess uncertainty in model parameters.

RESULTS

Compared with first-line ART only, second-line ART increased life expectancy by 24% with clinical monitoring only, 46% with CD4 monitoring, and 61% with HIV RNA monitoring. The incremental CE ratio of switching based on clinical monitoring was $1670 per year of life gained (YLS) compared with first-line ART only; biannual CD4 monitoring was $2120 per YLS. The CE ratio of biannual HIV RNA testing ranged from $2920 ($87/test) to $1990 per YLS ($25/test). If second-line ART costs were reduced, the CE of HIV RNA monitoring improved.

CONCLUSIONS

In resource-limited settings, CD4 count and HIV RNA monitoring to guide switching to second-line ART improve survival and, under most conditions, are cost-effective.

AIDS and drug rationing

Financial shortage in resource-limited and poor countries restricts treatment in HIV-infected patients especially in poor countries. Higher HIV prevalence in poorer countries makes drug rationing a real concern. Different countries solve the problem with different methods regarding WHO guidelines, but fairness and equity should be a major consideration in drug rationing. This paper is aimed at reviewing different strategic approaches to drug rationing in AIDS treatment and then discusses pharmacists' role. In conclusion, there is no fair and equitable strategy, and in each society, cultural, ethical and socioeconomic issues along with considering a critical role for pharmacists must be taken into account.

Further benefits by early start of HIV treatment in low income countries: survival estimates of early versus deferred antiretroviral therapy

BACKGROUND

International HIV guidelines have recently shifted from a medium-late to an early-start treatment strategy. As a consequence, more people will be eligible to Highly Active Antiretroviral Therapy (HAART). We estimate mean life years gained using different treatment indications in low income countries.

METHODS

We carried out a systematic search to identify relevant studies on the treatment effect of HAART. Outcome from identified observational studies were combined in a pooled-analyses and we apply these data in a Markov life cycle model based on a hypothetical Tanzanian HIV population. Survival for three different HIV populations with and without any treatment is estimated. The number of patients included in our pooled-analysis is 35,047.

RESULTS

Providing HAART early when CD4 is 200-350 cells/microl is likely to be the best outcome strategy with an expected net benefit of 14.5 life years per patient. The model predicts diminishing treatment benefits for patients starting treatment when CD4 counts are lower. Patients starting treatment at CD4 50-199 and <50 cells/microl have expected net health benefits of 7.6 and 7.3 life years. Without treatment, HIV patients with CD4 counts 200-350; 50-199 and < 50 cells/microl can expect to live 4.8; 2.0 and 0.7 life years respectively.

CONCLUSIONS

This study demonstrates that HIV patients live longer with early start strategies in low income countries. Since low income countries have many constraints to full coverage of HAART, this study provides input to a more transparent debate regarding where to draw explicit eligibility criteria during further scale up of HAART.

When to start antiretroviral therapy in resource-limited settings

BACKGROUND

The results of international clinical trials that are assessing when to initiate antiretroviral therapy (ART) will not be available for several years.

OBJECTIVE

To inform HIV treatment decisions about the optimal CD4 threshold at which to initiate ART in South Africa while awaiting the results of these trials.

DESIGN

Cost-effectiveness analysis by using a computer simulation model of HIV disease.

DATA SOURCES

Published data from randomized trials and observational cohorts in South Africa.

TARGET POPULATION

HIV-infected patients in South Africa.

TIME HORIZON

5-year and lifetime.

PERSPECTIVE

Modified societal.

INTERVENTION

No treatment, ART initiated at a CD4 count less than 0.250 x 10(9) cells/L, and ART initiated at a CD4 count less than 0.350 x 10(9) cells/L.

OUTCOME MEASURES

Morbidity, mortality, life expectancy, medical costs, and cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

If 10% to 100% of HIV-infected patients are identified and linked to care, a CD4 count threshold for ART initiation of 0.350 x 10(9) cells/L would reduce severe opportunistic diseases by 22,000 to 221,000 and deaths by 25,000 to 253,000 during the next 5 years compared with ART initiation at 0.250 x 10(9) cells/L; cost increases would range from $142 million (10%) to $1.4 billion (100%). Either ART initiation strategy would increase long-term survival by at least 7.9 years, with a mean per-person life expectancy of 3.8 years with no ART and 12.5 years with an initiation threshold of 0.350 x 10(9) cells/L. Compared with an initiation threshold of 0.250 x 10(9) cells/L, a threshold of 0.350 x 10(9) cells/L has an incremental cost-effectiveness ratio of $1200 per year of life saved.

RESULTS OF SENSITIVITY ANALYSIS

Initiating ART at a CD4 count less than 0.350 x 10(9) cells/L would remain cost-effective over the next 5 years even if the probability that the trial would demonstrate the superiority of earlier therapy is as low as 17%.

LIMITATION

This model does not consider the possible benefits of initiating ART at a CD4 count greater than 0.350 x 10(9) cells/L or of reduced HIV transmission.

CONCLUSION

Earlier initiation of ART in South Africa will probably reduce morbidity and mortality, improve long-term survival, and be cost-effective. While awaiting trial results, treatment guidelines should be liberalized to allow initiation at CD4 counts less than 0.350 x 10(9) cells/L, earlier than is currently recommended.

PRIMARY FUNDING SOURCE

National Institute of Allergy and Infectious Diseases and the Doris Duke Charitable Foundation.

Prevalence of drug-resistant HIV-1 in rural areas of Hubei province in the People's Republic of China

OBJECTIVE

To determine the prevalence of drug-resistant HIV-1 and the efficacy of first-line highly active antiretroviral therapy (HAART) regimens consisted of generic nucleoside reverse transcriptase inhibitor and nonnucleoside reverse transcriptase inhibitor among 339 study subjects in rural areas of Hubei province, China.

METHODS

Two cross-sectional studies were conducted to investigate 150 HAART-naive (99 received subsequent therapy) between 2003 and 2005 and 288 HAART-experienced patients mainly between 2005 and 2006. Patients' CD4+ T-cell count and viral load were determined. HIV-1 pol gene fragments were amplified from patients' plasma by reverse transcriptase-polymerase chain reaction, subsequently sequenced and analyzed.

RESULTS

About 83.5% of the patients were from rural villages. They were dominantly infected with subtype B' HIV-1 (96.7%) through paid blood donation (64.6%) and related blood transfusion (28.3%). We found that there was a steady increase of CD4 count over time among treated patients without detectable viral load (186/288, 64.6%). There was, however, an increasing prevalence of nucleoside reverse transcriptase inhibitor- and nonnucleoside reverse transcriptase inhibitor-resistant mutations among patients with detected viremia (102/288, 35.4%) after treatment for 3-6 (24.3%), 9-12 (57.1%), and 20-24 (63.3%) months, respectively. The increasing rates were associated with significant CD4 count drop and viral load increase. Some patients also developed multidrug-resistant mutants.

CONCLUSIONS

: We report the first HIV-1 drug resistance study after 2 years on HAART among Chinese patients living in rural villages. Our data suggest that a significant portion of patients are failing first-line regimens with a trend of AIDS progression. It is therefore necessary to maximize the drug adherence and to make affordable second-line HAART regimens available immediately. Our results have implications for implementing HAART in underresourced developing country settings.

Low prevalence of detectable HIV plasma viremia in patients treated with antiretroviral therapy in Burkina Faso and Mali

BACKGROUND

Sub-Saharan Africa has seen dramatic increases in the numbers of people treated with antiretroviral therapy (ART). Although standard ART regimens are now universally applied, viral load measurement is not currently part of standard monitoring protocols in sub-Saharan Africa.

METHODS

We describe the prevalence of inadequate virological response (IVR) to ART (viral load >or= 500 copies/mL) and identify factors associated with this outcome in 606 HIV-positive patients treated for at least 6 months. Recruitment took place in 7 hospitals and community-based sites in Bamako and Ouagadougou, and information was collected using medical charts and interviews.

RESULTS

The overall prevalence of IVR in treatment-naive patients was 12.3% and 24.4% for pretreated patients. There were no differences in rates of IVR according to ART delivery sites and time on treatment. Patients living farther away [odds ratio (OR) = 2.48; 95% confidence interval (CI) 1.40 to 4.39], those on protease inhibitor or nucleoside reverse transcriptase inhibitor regimens (OR = 3.23; 95% CI 1.79 to 5.82) and those reporting treatment interruptions (OR = 2.36; 95% CI 1.35 to 4.15), had increased odds of IVR. Immune suppression (OR = 3.32, 95% CI 1.94 to 5.70) and poor self-rated health (OR = 2.00; 95% CI 1.17 to 3.41) were also associated with IVR.

CONCLUSIONS

Sufficient expertise and dedication exist in public hospital and community-based programs to achieve rates of treatment success comparable to better-resourced settings.

Pharmacoepidemiological approach to the predisposing factors for highly active antiretroviral therapy failure in an HIV-positive cohort from Cordoba City (Argentina) 1995-2005

Highly active antiretroviral therapy (HAART) restores immunity, avoids resistance and delays disease progression. Nonetheless, adverse medicament reactions (AMRs) and therapeutic failure (TF) are still deleterious events. Consequently, their predisposing factors should be evaluated. Data from 181 men and 28 women of an Argentinean cohort (1995-2005) were collected and analysed by logistic regression, studying 63 schemes (15 active principles). The AMRs were the main cause of scheme change, followed by TF and medicament simplification, without influence of age and sex. Twenty-nine schemes exhibited TF at least once. Compared with zidovudine-lamivudine-nevirapine (success: >75%), the following schemes fail more frequently (P < 0.01): pre-HAART (8-fold), indinavir-containing ones (30-fold) and retrotranscriptase inhibitors with > or =3 protease inhibitors (11-fold). Inadequate patient adherence preceded failure (>95%), but not successful treatments, with a strong AMR-TF association (P < 0.005). Although some schemes had inherently increased TF, low adherence, drug toxicity and TF were critically interrelated, interfering with HAART goals.

The cost-effectiveness of antiretroviral therapy for treating HIV disease in the Caribbean

BACKGROUND

Antiretroviral therapy (ART) recently became available in the Organization of Eastern Caribbean States (OECS). Survival benefits and budgetary implications associated with universal access to ART have not been examined in the Caribbean.

METHODS

Using a state-transition simulation model of HIV with regional data, we projected survival, cost, and cost-effectiveness of treating an HIV-infected cohort. We examined 1 or 2 ART regimens and cotrimoxazole. In sensitivity analysis, we varied HIV natural history and ART efficacy, cost, and switching criteria.

RESULTS

Without treatment, mean survival was 2.30 years (mean baseline CD4 count = 288 cells/microL). One ART regimen with cotrimoxazole when the CD4 count was <350 cells/microL provided an additional 5.86 years of survival benefit compared with no treatment; the incremental cost-effectiveness ratio was $690 per year of life saved (YLS). A second regimen added 1.04 years of survival benefit; the incremental cost-effectiveness ratio was $10,960 per YLS compared with 1 regimen. Results were highly dependent on second-line ART costs. Per-person lifetime costs decreased from $17,020 to $9290 if second-line ART costs decreased to those available internationally, yielding approximately $8 million total savings.

CONCLUSIONS

In the OECS, ART is cost-effective by international standards. Reducing second-line ART costs increases cost-effectiveness and affordability. Current funding supports implementing universal access regionally over the next year, but additional funding is required to sustain lifetime care for currently infected persons.

Clinical impact and cost-effectiveness of antiretroviral therapy in India: starting criteria and second-line therapy

BACKGROUND

India has more than 5.7 million people infected with human immunodeficiency virus (HIV). In 2004, the Indian government began providing antiretroviral therapy (ART), and there are now an estimated 56 500 people receiving ART.

OBJECTIVE

To project the life expectancy, cost, and cost-effectiveness associated with different strategies for using ART in India, to inform treatment programs.

METHODS

We utilized an HIV disease simulation model, incorporating data on natural history, treatment efficacy, and costs of care from India. Input parameters for the simulated cohort included mean age 32.6 years and mean CD4 count 318 cells/microl (SD 291 cells/microl). We examined different criteria for starting and stopping ART with a first-line regimen of stavudine/lamivudine/nevirapine, and the impact of a second-line protease-inhibitor-based regimen. Cost-effectiveness in US dollars per year of life saved (US$/YLS) was compared incrementally among alternative starting, sequencing, and stopping criteria.

RESULTS

Discounted (undiscounted) mean survival ranged from 34.5 (37.5) months with no ART to 64.7 (73.6) months with one line of therapy initiated at CD4 <350 cells/microl, to 88.9 (106.5) months with two lines of therapy initiated at CD4 <350 cells/microl. Lifetime medical costs ranged from US$530 (no ART) to US$5430 (two ART regimens) per person. With one line of therapy, the incremental cost-effectiveness ratios ranged from US$430/YLS to US$550/YLS as the CD4 starting criterion was increased from CD4 <250 cells/microl to <350 cells/microl. Use of two lines of therapy had an incremental cost-effectiveness ratio of US$1880/YLS compared with the use of first-line therapy alone. Results were sensitive to the costs of second-line therapy and criteria for stopping therapy.

CONCLUSIONS

In India, antiretroviral therapy will lead to major survival benefits and is cost-effective by World Health Organization criteria. The availability of second-line regimens will further increase survival, but their cost-effectiveness depends on their relative cost compared with first-line regimens.