Cost-effectiveness of alternative strategies for initiating and monitoring highly active antiretroviral therapy in the developing world

Point-of-Care HIV Viral Load Testing: an Essential Tool for a Sustainable Global HIV/AIDS Response

The global public health community has set ambitious treatment targets to end the HIV/AIDS pandemic. With the notable absence of a cure, the goal of HIV treatment is to achieve sustained suppression of an HIV viral load, which allows for immunological recovery and reduces the risk of onward HIV transmission. Monitoring HIV viral load in people living with HIV is therefore central to maintaining effective individual antiretroviral therapy as well as monitoring progress toward achieving population targets for viral suppression. The capacity for laboratory-based HIV viral load testing has increased rapidly in low- and middle-income countries, but implementation of universal viral load monitoring is still hindered by several barriers and delays. New devices for point-of-care HIV viral load testing may be used near patients to improve HIV management by reducing the turnaround time for clinical test results. The implementation of near-patient testing using these new and emerging technologies may be an essential tool for ensuring a sustainable response that will ultimately enable an end to the HIV/AIDS pandemic. In this report, we review the current and emerging technology, the evidence for decentralized viral load monitoring by non-laboratory health care workers, and the additional considerations for expanding point-of-care HIV viral load testing.

The per-patient costs of HIV services in South Africa: Systematic review and application in the South African HIV Investment Case

Background

In economic analyses of HIV interventions, South Africa is often used as a case in point, due to the availability of good epidemiological and programme data and the global relevance of its epidemic. Few analyses however use locally relevant cost data. We reviewed available cost data as part of the South African HIV Investment Case, a modelling exercise to inform the optimal use of financial resources for the country’s HIV programme.

Methods

We systematically reviewed publication databases for published cost data covering a large range of HIV interventions and summarised relevant unit costs (cost per person receiving a service) for each. Where no data was found in the literature, we constructed unit costs either based on available information regarding ingredients and relevant public-sector prices, or based on expenditure records.

Results

Only 42 (5%) of 1,047 records included in our full-text review reported primary cost data on HIV interventions in South Africa, with 71% of included papers covering ART. Other papers detailed the costs of HCT, MMC, palliative and inpatient care; no papers were found on the costs of PrEP, social and behaviour change communication, and PMTCT. The results informed unit costs for 5 of 11 intervention categories included in the Investment Case, with the remainder costed based on ingredients (35%) and expenditure data (10%).

Conclusions

A large number of modelled economic analyses of HIV interventions in South Africa use as inputs the same, often outdated, cost analyses, without reference to additional literature review. More primary cost analyses of non-ART interventions are needed.

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.

Does directly administered antiretroviral therapy represent good value for money in sub-Saharan Africa? A cost-utility and value of information analysis

BACKGROUND

Successful antiretroviral therapy (ART) relies on the optimal level of ART adherence to achieve reliable viral suppression, avert HIV drug resistance, and prevent avoidable deaths. It has been shown that there are various groups of people living with HIV at high-risk of non-adherence to ART in sub-Saharan Africa. The objective of this study was to examine the cost effectiveness and value-of-information of directly administered antiretroviral therapy (DAART) versus self-administered ART among people living with HIV, at high risk of non-adherence to ART in sub-Saharan Africa.

METHODS AND FINDINGS

A Markov model was developed that describes the transition between HIV stages based on the CD4 count, along with direct costs, quality of life and the mortality rate associated with DAART in comparison with self-administered ART. Data used in the model were derived from the published literature. A health system perspective was employed using a life-time time horizon. Probabilistic sensitivity analysis was performed to determine the impact of parameter uncertainty. Value of information analysis was also conducted. The expected cost of self-administered ART and DAART were $5,200 and $15,500 and the expected QALYs gained were 8.52 and 9.75 respectively, giving an incremental cost effectiveness ratio of $8,400 per QALY gained. The analysis demonstrated that the annual cost DAART needs to be priced below $200 per patient to be cost-effective. The probability that DAART was cost-effective was 1% for a willingness to pay threshold of $5,096 for sub-Saharan Africa. The value of information associated with the cost of DAART and its effectiveness was substantial.

CONCLUSIONS

From the perspective of the health care payer in sub-Saharan Africa, DAART cannot be regarded as cost-effective based on current information. The value of information analysis showed that further research will be worthwhile and potentially cost-effective in resolving the uncertainty about whether or not to adopt DAART.

Cost-effectiveness of routine viral load monitoring in low- and middle-income countries: a systematic review

INTRODUCTION

Routine viral load monitoring for HIV-1 management of persons on antiretroviral therapy (ART) has been recommended by the World Health Organization (WHO) to identify treatment failure. However, viral load testing represents a substantial cost in resource constrained health care systems. The central challenge is whether and how viral load monitoring may be delivered such that it maximizes health gains across the population for the costs incurred. We hypothesized that key features of program design and delivery costs drive the cost-effectiveness of viral load monitoring within programs.

METHODS

We conducted a systematic review of studies on the cost-effectiveness of viral load monitoring in low- and middle-income countries (LMICs). We followed the Cochrane Collaboration guidelines and the PRISMA reporting guidelines.

RESULTS AND DISCUSSION

We identified 18 studies that evaluated the cost-effectiveness of viral load monitoring in HIV treatment programs. Overall, we identified three key factors that make it more likely for viral load monitoring to be cost-effective: 1) Use of effective, lower cost approaches to viral load monitoring (e.g. use of dried blood spots); 2) Ensuring the pathway to health improvement is established and that viral load results are acted upon; and 3) Viral load results are used to simplify HIV care in patients with viral suppression (i.e. differentiated care, with fewer clinic visits and longer prescriptions). Within the context of differentiated care, viral load monitoring has the potential to double the health gains and be cost saving compared to the current standard (CD4 monitoring).

CONCLUSIONS

The cost-effectiveness of viral load monitoring critically depends on how it is delivered and the program context. Viral load monitoring as part of differentiated HIV care is likely to be cost-effective. Viral load monitoring in differentiated care programs provides evidence that reduced clinical engagement, where appropriate, is not impacting health outcomes. Introducing viral load monitoring without differentiated care is unlikely to be cost-effective in most settings and results in lost opportunity for health gains through alternative uses of limited resources. As countries scale up differentiated care programs, data on viral suppression outcomes and costs should be collected to evaluate the on-going cost-effectiveness of viral load monitoring as utilized in practice.

Initiation of antiretroviral therapy based on the 2015 WHO guidelines

OBJECTIVE

In 2015, the WHO recommended initiation of antiretroviral therapy (ART) in all HIV-positive patients regardless of CD4 cell count. We evaluated the cost-effectiveness of immediate versus deferred ART initiation among patients with CD4 cell counts exceeding 500cells/μl in four resource-limited countries (South Africa, Nigeria, Uganda, and India).

DESIGN

A 5-year Markov model with annual cycles, including patients at CD4 cell counts more than 500 cells/μl initiating ART or deferring therapy until historic ART initiation criteria of CD4 cell counts more than 350 cells/μl were met.

METHODS

The incidence of opportunistic infections, malignancies, cardiovascular disease, unscheduled hospitalizations, and death, were informed by the START trial results. Risk of HIV transmission was obtained from a systematic review. Disability weights were based on published literature. Cost inputs were inflated to 2014 US dollars and based on local sources. Results were expressed in cost per disability-adjusted life years averted and measured against WHO cost-effectiveness thresholds.

RESULTS

Immediate initiation of ART is associated with a cost per disability-adjusted life years averted of -$317 [95% confidence interval (CI): -$796-$817] in South Africa; -$507 (95% CI: -$765-$837) in Nigeria; -$136 (-$382-$459) in Uganda; and -$78 (-$256-$374) in India. The results are largely driven by the impact of ART on reducing the risk of new HIV transmissions.

CONCLUSIONS

In HIV-positive patients with CD4 counts above 500 cells/μl in the four studied countries, immediate initiation of ART versus deferred therapy until historic eligibility criteria are met is cost-effective and likely even cost-saving over time.

Potential impact of multiple interventions on HIV incidence in a hyperendemic region in Western Kenya: a modelling study

BACKGROUND

Multiple prevention interventions, including early antiretroviral therapy initiation, may reduce HIV incidence in hyperendemic settings. Our aim was to predict the short-term impact of various single and combined interventions on HIV spreading in the adult population of Ndhiwa subcounty (Nyanza Province, Kenya).

METHODS

A mathematical model was used with data on adults (15-59 years) from the Ndhiwa HIV Impact in Population Survey to compare the impacts on HIV prevalence, HIV incidence rate, and population viral load suppression of various interventions. These interventions included: improving the cascade of care (use of three guidelines), increasing voluntary medical male circumcision (VMMC), and implementing pre-exposure prophylaxis (PrEP) use among HIV-uninfected women.

RESULTS

After four years, improving separately the cascade of care under the WHO 2013 guidelines and under the treat-all strategy would reduce the overall HIV incidence rate by 46 and 58 %, respectively, vs. the baseline rate, and by 35 and 49 %, respectively, vs. the implementation of the current Kenyan guidelines. With conservative and optimistic scenarios, VMMC and PrEP would reduce the HIV incidence rate by 15-25 % and 22-28 % vs. the baseline, respectively. Combining the WHO 2013 guidelines with VMMC would reduce the HIV incidence rate by 35-56 % and combining the treat-all strategy with VMMC would reduce it by 49-65 %. Combining the WHO 2013 guidelines, VMMC, and PrEP would reduce the HIV incidence rate by 46-67 %.

CONCLUSIONS

The impacts of the WHO 2013 guidelines and the treat-all strategy were relatively close; their implementation is desirable to reduce HIV spread. Combining several strategies is promising in adult populations of hyperendemic areas but requires regular, reliable, and costly monitoring.

A narrative review of cost-effectiveness analysis of people living with HIV treated with HAART: from interventions to outcomes

Background

Since its introduction in 1996, highly active antiretroviral therapy (HAART), which involves the combination of antiretroviral drugs, has resulted in significant improvements in the morbidity, mortality, and life expectancy of HIV-infected patients. Numerous studies of the cost-effectiveness of HAART from different perspectives in HIV have been reported.

Aim

To investigate the economic outcomes and relevance of HAART for people living with HIV.

Materials and methods

A narrative literature review was conducted on 22 peer-reviewed full economic evaluations of people living with HIV treated with different HAART regimens and published in English between January 2005 and December 2014. Information regarding study details, such as interventions, outcomes, and modeling methods, was extracted. The high heterogeneity of the included studies rendered a meta-analysis inappropriate; therefore, we conducted a comparative analysis of studies grouped according to the similarity of the different intervention types and outcomes.

Results

Most of the economic evaluations of HAART focused on comparisons between the specific HAART regimens and others from the following perspectives: injecting drug users versus noninjecting drug users, HIV-infected adults without AIDS versus those with AIDS, regimens based on developed world guidelines versus those based on developing world guidelines, self-administered HAART versus directly observed HAART, and “ideal” versus “typical” regimens.

Conclusion

In general, HAART is more cost-effective than other therapeutic regimens adopted so far. Further investigations, especially head-to-head comparisons of “ideal” and “typical” trials of different regimen combinations, are required to identify the optimal HAART regimens.

The cost-effectiveness of monitoring strategies for antiretroviral therapy of HIV infected patients in resource-limited settings: software tool

Background

The cost-effectiveness of routine viral load (VL) monitoring of HIV-infected patients on antiretroviral therapy (ART) depends on various factors that differ between settings and across time. Low-cost point-of-care (POC) tests for VL are in development and may make routine VL monitoring affordable in resource-limited settings. We developed a software tool to study the cost-effectiveness of switching to second-line ART with different monitoring strategies, and focused on POC-VL monitoring.

Methods

We used a mathematical model to simulate cohorts of patients from start of ART until death. We modeled 13 strategies (no 2^nd-line, clinical, CD4 (with or without targeted VL), POC-VL, and laboratory-based VL monitoring, with different frequencies). We included a scenario with identical failure rates across strategies, and one in which routine VL monitoring reduces the risk of failure. We compared lifetime costs and averted disability-adjusted life-years (DALYs). We calculated incremental cost-effectiveness ratios (ICER). We developed an Excel tool to update the results of the model for varying unit costs and cohort characteristics, and conducted several sensitivity analyses varying the input costs.

Results

Introducing 2^nd-line ART had an ICER of US$1651-1766/DALY averted. Compared with clinical monitoring, the ICER of CD4 monitoring was US$1896-US$5488/DALY averted and VL monitoring US$951-US$5813/DALY averted. We found no difference between POC- and laboratory-based VL monitoring, except for the highest measurement frequency (every 6 months), where laboratory-based testing was more effective. Targeted VL monitoring was on the cost-effectiveness frontier only if the difference between 1^st- and 2^nd-line costs remained large, and if we assumed that routine VL monitoring does not prevent failure.

Conclusion

Compared with the less expensive strategies, the cost-effectiveness of routine VL monitoring essentially depends on the cost of 2^nd-line ART. Our Excel tool is useful for determining optimal monitoring strategies for specific settings, with specific sex-and age-distributions and unit costs.

Increasing the use of second-line therapy is a cost-effective approach to prevent the spread of drug-resistant HIV: a mathematical modelling study

Introduction

Earlier antiretroviral therapy (ART) initiation reduces HIV-1 incidence. This benefit may be offset by increased transmitted drug resistance (TDR), which could limit future HIV treatment options. We analyze the epidemiological impact and cost-effectiveness of strategies to reduce TDR.

Methods

We develop a deterministic mathematical model representing Kampala, Uganda, to predict the prevalence of TDR over a 10-year period. We then compare the impact on TDR and cost-effectiveness of: (1) introduction of pre-therapy genotyping; (2) doubling use of second-line treatment to 80% (50–90%) of patients with confirmed virological failure on first-line ART; and (3) increasing viral load monitoring from yearly to twice yearly. An intervention can be considered cost-effective if it costs less than three times the gross domestic product per capita per quality adjusted life year (QALY) gained, or less than $3420 in Uganda.

Results

The prevalence of TDR is predicted to rise from 6.7% (interquartile range [IQR] 6.2–7.2%) in 2014, to 6.8% (IQR 6.1–7.6%), 10.0% (IQR 8.9–11.5%) and 11.1% (IQR 9.7–13.0%) in 2024 if treatment is initiated at a CD4 <350, <500, or immediately, respectively. The absolute number of TDR cases is predicted to decrease 4.4–8.1% when treating earlier compared to treating at CD4 <350 due to the preventative effects of earlier treatment. Most cases of TDR can be averted by increasing second-line treatment (additional 7.1–10.2% reduction), followed by increased viral load monitoring (<2.7%) and pre-therapy genotyping (<1.0%). Only increasing second-line treatment is cost-effective, ranging from $1612 to $2234 (IQR $450-dominated) per QALY gained.

Conclusions

While earlier treatment initiation will result in a predicted increase in the proportion of patients infected with drug-resistant HIV, the absolute numbers of patients infected with drug-resistant HIV is predicted to decrease. Increasing use of second-line treatment to all patients with confirmed failure on first-line therapy is a cost-effective approach to reduce TDR. Improving access to second-line ART is therefore a major priority.

HIV epidemic control-a model for optimal allocation of prevention and treatment resources

With 33 million people living with human immunodeficiency virus (HIV) worldwide and 2.7 million new infections occurring annually, additional HIV prevention and treatment efforts are urgently needed. However, available resources for HIV control are limited and must be used efficiently to minimize the future spread of the epidemic. We develop a model to determine the appropriate resource allocation between expanded HIV prevention and treatment services. We create an epidemic model that incorporates multiple key populations with different transmission modes, as well as production functions that relate investment in prevention and treatment programs to changes in transmission and treatment rates. The goal is to allocate resources to minimize R 0, the reproductive rate of infection. We first develop a single-population model and determine the optimal resource allocation between HIV prevention and treatment. We extend the analysis to multiple independent populations, with resource allocation among interventions and populations. We then include the effects of HIV transmission between key populations. We apply our model to examine HIV epidemic control in two different settings, Uganda and Russia. As part of these applications, we develop a novel approach for estimating empirical HIV program production functions. Our study provides insights into the important question of resource allocation for a country's optimal response to its HIV epidemic and provides a practical approach for decision makers. Better decisions about allocating limited HIV resources can improve response to the epidemic and increase access to HIV prevention and treatment services for millions of people worldwide.

Cost-effectiveness of point-of-care viral load monitoring of antiretroviral therapy in resource-limited settings: mathematical modelling study

BACKGROUND

Monitoring of HIV viral load in patients on combination antiretroviral therapy (ART) is not generally available in resource-limited settings. We examined the cost-effectiveness of qualitative point-of-care viral load tests (POC-VL) in sub-Saharan Africa.

DESIGN

Mathematical model based on longitudinal data from the Gugulethu and Khayelitsha township ART programmes in Cape Town, South Africa.

METHODS

Cohorts of patients on ART monitored by POC-VL, CD4 cell count or clinically were simulated. Scenario A considered the more accurate detection of treatment failure with POC-VL only, and scenario B also considered the effect on HIV transmission. Scenario C further assumed that the risk of virologic failure is halved with POC-VL due to improved adherence. We estimated the change in costs per quality-adjusted life-year gained (incremental cost-effectiveness ratios, ICERs) of POC-VL compared with CD4 and clinical monitoring.

RESULTS

POC-VL tests with detection limits less than 1000 copies/ml increased costs due to unnecessary switches to second-line ART, without improving survival. Assuming POC-VL unit costs between US$5 and US$20 and detection limits between 1000 and 10,000 copies/ml, the ICER of POC-VL was US$4010-US$9230 compared with clinical and US$5960-US$25540 compared with CD4 cell count monitoring. In Scenario B, the corresponding ICERs were US$2450-US$5830 and US$2230-US$10380. In Scenario C, the ICER ranged between US$960 and US$2500 compared with clinical monitoring and between cost-saving and US$2460 compared with CD4 monitoring.

CONCLUSION

The cost-effectiveness of POC-VL for monitoring ART is improved by a higher detection limit, by taking the reduction in new HIV infections into account and assuming that failure of first-line ART is reduced due to targeted adherence counselling.

Parenting styles and emotional intelligence of HIV-affected children in Thailand

The purpose of this study was to examine the impact of parenting styles on emotional intelligence of HIV-affected children in Thailand. This study uses data from 205 HIV-affected children in northern and northeastern Thailand. Correlation and regression analyses were used to examine the predictors of emotional intelligence. Children reporting higher levels of stress reported less caring parenting style (standardized beta [B]=-0.18, p=0.050). Children with higher self-esteem were also more likely to perceive their parents as caring (B=0.48, p=0.002). Children who scored lower on their self-esteem reported their parents to be more overprotective (B=-0.30, p=0.030), and children reporting higher levels of stress reported their parents to be more overprotective (B=0.12, p=0.010). Children reporting caring parenting style were significantly more likely to report higher emotional intelligence (B=0.66, p=0.001). Parenting styles play an important role in the emotional intelligence. Identifying and testing interventions to help parents improve their parenting styles, while helping their HIV-affected children cope with stress and self-esteem, are essential in promoting mental health of HIV-affected children in Thailand.

A novel Markov model projecting costs and outcomes of providing antiretroviral therapy to public patients in private practices versus public clinics in South Africa

INTRODUCTION

Providing private antiretroviral therapy (ART) care for public sector patients could increase access to ART in low- and middle-income countries. We compared the costs and outcomes of a private-care and a public-care ART program in South Africa.

METHODS

A novel Markov model was developed from the public-care program. Patients were first tunneled for 6 months in their baseline CD4 category before being distributed into a dynamic CD4 and viral load model. Patients were allowed to return to ART care from loss to follow up (LTFU). We then populated this modeling framework with estimates derived from the private-care program to externally validate the model.

RESULTS

Baseline characteristics were similar in the two programs. Clinic visit utilization was higher and death rates were lower in the first few years on ART in the public-care program. After 10 years on ART we estimated the following outcomes in the public-care and private-care programs respectively: viral load <1000 copies/ml 89% and 84%, CD4 >500 cells/μl 33% and 37%, LTFU 14% and 14%, and death 27% and 32%. Lifetime undiscounted survival estimates were 14.1 (95%CI 13.2-14.9) and (95%CI 12.7-14.5) years with costs of 18,734 (95%CI 12,588-14,022) and 13,062 (95%CI 12,077-14,047) USD in the private-care and public-care programs respectively. When clinic visit utilization in the public-care program was reduced by two thirds after the initial 6 months on ART, which is similar to their current practice, the costs were comparable between the programs.

CONCLUSIONS

Using a novel Markov model, we determined that the private-care program had similar outcomes but lower costs than the public-care program, largely due to lower visit frequencies. These findings have important implications for increasing and sustaining coverage of patients in need of ART care in resource-limited settings.

The state of health economic research in South Africa: a systematic review

BACKGROUND

Economic factors are a limiting factor toward the implementation of many health programmes and interventions. Economic evaluation has a great potential to contribute toward cost-effective healthcare delivery in South Africa. Little is known about the characteristics and quality of health economic (including pharmacoeconomic) research in South Africa.

OBJECTIVE AND METHODS

This study assessed the state of health economic (including pharmacoeconomic) research in South Africa. PUBMED, MEDLINE, HealthSTAR, EconLit and PsycINFO databases were searched to identify health economic articles pertaining to South Africa published between 1 January 1977 and 30 April 2010. The searches used the following Medical Subject Headings (MeSH) terms and text words alone and in combination: 'costs', 'health' and 'South Africa'. Our study included only original economic studies/analyses that pertained to South Africa, addressed a health-related topic, and had a statement or word in the title, abstract or keywords that indicated that an economic (including cost) analysis had been conducted. The study only included complete peer-reviewed publications (e.g. abstracts were excluded) that were reported in the English language. Two reviewers independently scored each article in the final sample using the data collection form designed for the study.

RESULTS

In total, 108 studies investigating a wide variety of diseases were included in the study. These articles were published in 39 different journals mostly based outside of South Africa between 1977 and 2010. On average, each article was written by three authors. Most first authors had medical/clinical training and resided in South Africa at the time of publication of their study. Based on a 1-10 scale, with 10 indicating the highest quality, the mean quality score for all studies was 7.59 (SD 1.42) and half of the articles were of good quality (score 8-10) The quality of studies was related to the country in which the journal publishing the article was based (outside South Africa = higher); current residence of the primary author (outside South Africa = higher); method of economic analysis (economic evaluations higher than cost studies); type of data used (secondary higher than primary); primary training of the first author (health economics/pharmacoeconomics = higher); type of medical function (diagnosis = higher); study perspective (societal = higher); primary health intervention (pharmaceuticals = higher); study design (modelling = higher); number of authors (more = higher); and year of publication (more recent = higher) [p ≤ 0.05].

CONCLUSION

Half of the articles were of poor or fair quality. Measures are needed to promote the commissioning of more and better quality health economic and pharmacoeconomic studies in South Africa.

Cost-effectiveness of early initiation of first-line combination antiretroviral therapy in Uganda

BACKGROUND

Ugandan national guidelines recommend initiation of combination antiretroviral therapy (cART) at CD4+ T cell (CD4) count below 350 cell/μl, but the implementation of this is limited due to availability of medication. However, cART initiation at higher CD4 count increases survival, albeit at higher lifetime treatment cost. This analysis evaluates the cost-effectiveness of initiating cART at a CD4 count between 250-350 cell/μl (early) versus <250 cell/μl (delayed).

METHODS

Life expectancy of cART-treated patients, conditional on baseline CD4 count, was modeled based on published literature. First-line cART costs $192 annually, with an additional $113 for patient monitoring. Delaying initiation of cART until the CD4 count falls below 250 cells/μl would incur the cost of the bi-annual CD4 count tests and routine maintenance care at $85 annually. We compared lifetime treatment costs and disability adjusted life-expectancy between early vs. delayed cART for ten baseline CD4 count ranges from 250-350 cell/μl. All costs and benefits were discounted at 3% annually.

RESULTS

Treatment delay varied from 6-18 months. Early cART initiation increased life expectancy from 1.5-3.5 years and averted 1.33-3.10 disability adjusted life years (DALY's) per patient. Lifetime treatment costs were $4,300-$5,248 for early initiation and $3,940-$4,435 for delayed initiation. The cost/DALY averted of the early versus delayed start ranged from $260-$270.

CONCLUSIONS

In HIV-positive patients presenting with CD4 count between 250-350 cells/μl, immediate initiation of cART is a highly cost-effective strategy using the recommended one-time per capita GDP threshold of $490 reported for Uganda. This would constitute an efficient use of scarce health care funds.

Monitoring the efficacy of antiretroviral therapy by a simple reverse transcriptase assay in HIV-infected adults in rural Vietnam

Aim: To determine the feasibility of viral load (VL) monitoring using ExaVir™ Load in a cohort of 605 HIV treatment-naive adult patients initiating antiretroviral therapy in rural Vietnam. Materials & methods: VL monitoring every 6 months, survival and intention-to-treat analysis were used. Roche Cobas TaqMan® VL was compared with ExaVir Load using Spearman’s rank correlation coefficient and Bland–Altman analysis. Results: After 20.7 months mean follow-up time, 78% remained on treatment. Virologic suppression rate (VL <200 copies/ml) after 24 months was 64% in the whole cohort and 94% among patients assessed with VL. The cumulative virologic failure rate (VL >1000 copies/ml) was 6.8%. Baseline VL ≥100,000 copies/ml was predictive for virologic failure [adjusted hazard ratio: 2.26 (1.16–4.39); p = 0.016]. ExaVir Load and the Roche Cobas TaqMan showed a strong correlation (r2 = 0.97; p < 0.001), high agreement (difference in log = 0.34; 95% CI: -0.35–1.03), high sensitivity (98%) and high specificity (100%). Conclusion: Using ExaVir Load to monitor efficacy of antiretroviral therapy programs in resource-limited settings is feasible.

Cost-effectiveness of laboratory monitoring for management of HIV treatment in sub-Saharan Africa: a model-based analysis

OBJECTIVE

To compare the cost-effectiveness of three different strategies for long-term monitoring of antiretroviral therapy (ART) failure and regimen switching in sub-Saharan Africa: a symptom-based approach, or monitoring of either CD4 cell counts or plasma viral load (pVL).

DESIGN

Markov model.

SETTING AND PARTICIPANTS

Hypothetical HIV-infected adult population who began first-line ART and subsequently had up to 6 years of follow-up.

MAIN OUTCOME MEASURES

Total cost, life expectancy and incremental cost-effectiveness ratio (ICER).

RESULTS

A symptom-based approach yielded a life expectancy of 64.0 months at a total cost of US$ 4028 per person. All laboratory-based strategies, at testing intervals of 6 or 12 months, were cost-saving and improved life expectancy, compared with a symptom-based approach. The life-expectancy gain was larger for pVL than for CD4 strategies at 6-monthly (2.3 and 0.9 months, respectively) and 12-monthly testing (2.0 and 0.8 months, respectively). Cost-savings of 6-monthly pVL or CD4 testing were similar (US$ 630 and 621, respectively), whereas 12-monthly CD4 cell counts were more cost-saving than 12-monthly pVL (US$ 1132 and 880, respectively). Testing every 12 months - rather than every 6 months - decreased the ICER by 102% for CD4 cell count and 67% for pVL. These findings were robust to a wide range of deterministic sensitivity analyses, but were sensitive to the specificity and costs of diagnostic tests.

CONCLUSION

Additional diagnostic costs are balanced by cost-savings from avoiding unnecessary switching due to misdiagnosis of ART failure. Routine pVL monitoring may be preferred as a replacement for CD4 cell counts because of its additional public-health advantages in preventing drug-resistance, supporting adherence and reducing HIV transmission.

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.

HIV treatment as prevention: issues in economic evaluation

Meyer-Rath and Over assert in another article in the July 2012 PLoS Medicine Collection, "Investigating the Impact of Treatment on New HIV Infections", that economic evaluations of antiretroviral therapy (ART) in currently existing programs and in HIV treatment as prevention (TasP) programs should use cost functions that capture cost dependence on a number of factors, such as scale and scope of delivery, health states, ART regimens, health workers' experience, patients' time on treatment, and the distribution of delivery across public and private sectors. We argue that for particular evaluation purposes (e.g., to establish the social value of TasP) and from particular perspectives (e.g., national health policy makers) less detailed cost functions may be sufficient. We then extend the discussion of economic evaluation of TasP, describing why ART outcomes and costs assessed in currently existing programs are unlikely to be generalizable to TasP programs for several fundamental reasons. First, to achieve frequent, widespread HIV testing and high uptake of ART immediately following an HIV diagnosis, TasP programs will require components that are not present in current ART programs and whose costs are not included in current estimates. Second, the early initiation of ART under TasP will change not only patients' disease courses and treatment experiences--which can affect behaviors that determine clinical treatment success, such as ART adherence and retention--but also quality of life and economic outcomes for HIV-infected individuals. Third, the preventive effects of TasP are likely to alter the composition of the HIV-infected population over time, changing its biological and behavioral characteristics and leading to different costs and outcomes for ART.

Challenges in implementing HIV laboratory monitoring in resource-constrained settings: how to do more with less

Laboratory monitoring for HIV disease in resource-limited settings has now become one of the key challenges for antiretroviral treatment (ART) access and success, as emphasized by the 2010 revised WHO guidelines for ART in resource-limited settings. Thus, the most common method for initiating ART, and monitoring treatment response in resource-constrained environments is the measurement of CD4 T-cell count. Affordable CD4 T-cell counting has gradually been made possible by using simple, compact and robust, low-cost, new-generation cytometers, operating as single-platform volumetric instruments. Several cost-effective point-of-care CD4 T-cell testing options are also already on the market, in order to improve access to CD4 T-cell monitoring, especially for rural patients, and to reduce loss-to-follow-up of patients. In addition, HIV RNA viral load measurement is becoming increasingly important, mainly for a systematic confirmation of first-line ART failure before switching to second-line treatment to avoid belated as well as premature therapeutic decisions and their potentially negative consequences. Viral load testing should now be considered as the standard of care for therapeutic failure in all resource-limited settings. However, the measurement of HIV viral load remains a centralized marker, carried out in a limited number of reference laboratories. Finally, the costs of second-line ART regimens, rather than the laboratory test costs themselves, currently constitute the primary determinant of the total cost in ART switching. Laboratory monitoring strategies may become more attractive as price negotiations render second-line ART regimens less expensive worldwide.

HIV treatment as prevention: modelling the cost of antiretroviral treatment--state of the art and future directions

Policy discussions about the feasibility of massively scaling up antiretroviral therapy (ART) to reduce HIV transmission and incidence hinge on accurately projecting the cost of such scale-up in comparison to the benefits from reduced HIV incidence and mortality. We review the available literature on modelled estimates of the cost of providing ART to different populations around the world, and suggest alternative methods of characterising cost when modelling several decades into the future. In past economic analyses of ART provision, costs were often assumed to vary by disease stage and treatment regimen, but for treatment as prevention, in particular, most analyses assume a uniform cost per patient. This approach disregards variables that can affect unit cost, such as differences in factor prices (i.e., the prices of supplies and services) and the scale and scope of operations (i.e., the sizes and types of facilities providing ART). We discuss several of these variables, and then present a worked example of a flexible cost function used to determine the effect of scale on the cost of a proposed scale-up of treatment as prevention in South Africa. Adjusting previously estimated costs of universal testing and treatment in South Africa for diseconomies of small scale, i.e., more patients being treated in smaller facilities, adds 42% to the expected future cost of the intervention.

Monitoring of highly active antiretroviral therapy in HIV infection

PURPOSE OF REVIEW

Patients on antiretroviral therapy (ART) in high-income countries have routine laboratory tests to monitor ART efficacy/toxicity. We review studies describing the outcomes and costs of different monitoring approaches, predominantly in low-income countries.

RECENT FINDINGS

CD4 cell counts, HIV RNA viral load and clinical events are frequently discordant; viral load suppression occurs with WHO-defined CD4 failure and, as expected, viral load failure often occurs before CD4 failure. Routine CD4 monitoring provides small but significant mortality/morbidity benefits over clinical monitoring, but, at current prices, is not yet cost-effective in many sub-Saharan African countries. Viral load monitoring is less cost-effective with modelling studies reporting variable results. More research into point-of-care tests, methods for targeting monitoring and thresholds for defining failure is needed. Most laboratory monitoring for toxicity is neither effective nor cost-effective. In terms of models for delivery of care, task-shifting with nurse-led and decentralized care appear as effective as doctor-led or centralized care.

SUMMARY

Recent studies have improved the evidence base for monitoring on ART. Future research to increase cost-effectiveness by better targeting of monitoring and/or evaluating implementation of less costly point-of-care tests will contribute to long-term success of ART while continuing to increase ART coverage.

A decision tree to help determine the best timing and antiretroviral strategy in HIV-infected patients

Optimal antiretroviral strategies for HIV-infected patients still need to be established. To this end a decision tree including different antiretroviral strategies that could be adopted for HIV-infected patients was built. A 10-year follow-up was simulated by using transitional probabilities estimated from a large cohort using a time-homogeneous Markov model. The desired outcome was for patients to maintain a CD4 cell count of >500 cells/mm3 without experiencing AIDS or death. For patients with a baseline HIV viral load ⩾5 log10 copies/ml, boosted protease inhibitor-based immediate highly active antiretroviral therapy (HAART) allowed them to spend 12% more time with CD4 ⩾500/mm3 than did delayed HAART (6·40 vs. 5·69 and 5·57 vs. 4·90 years for baseline CD4 ⩾500 and 350–499/mm3, respectively). In patients with a baseline HIV viral load ⩽3·5 log10 copies/ml, delayed HAART performed better than immediate HAART (6·43 vs. 6·26 and 5·95 vs. 5·18 for baseline CD4 ⩾500 and 350–499/mm3, respectively). Immediate HAART is beneficial in patients with a baseline HIV viral load ⩾5 log10 copies/ml, whereas deferred HAART appears to be the best option for patients with CD4 ⩾350/mm3 and baseline HIV viral load <3·5 log10 copies/ml.

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.

Improving the evidence base of Markov models used to estimate the costs of scaling up antiretroviral programmes in resource-limited settings

BACKGROUND

Despite concerns about affordability and sustainability, many models of the lifetime costs of antiretroviral therapy (ART) used in resource limited settings are based on data from small research cohorts, together with pragmatic assumptions about life-expectancy. This paper revisits these modelling assumptions in order to provide input to future attempts to model the lifetime costs and the costs of scaling up ART.

METHODS

We analysed the determinants of costs and outcomes in patients receiving ART in line with standard World Health Organization (WHO) guidelines for resource poor settings in a private sector managed ART programme in South Africa. The cohort included over 5,000 patients with up to 4 years (median 19 months) on ART. Generalized linear and Cox proportional hazards regression models were used to establish cost and outcome determinants respectively.

RESULTS

The key variables associated with changes in mean monthly costs were: being on the second line regimen; receiving ART from 4 months prior to 4 months post treatment initiation; having a recent or current CD4 count <50 cells/microL or 50-199 cells/microl; having mean ART adherence <75% as determined by monthly pharmacy refill data; and having a current or recent viral load >100,000 copies/mL. In terms of the likelihood of dying, the key variables were: baseline CD4 count<50 cells/microl (particularly during the first 4 months on treatment); current CD4 count <50 cells/microl and 50-199 cells/microl (particularly during later periods on treatment); and being on the second line regimen. Being poorly adherent and having an unsuppressed viral load was also associated with a higher likelihood of dying.

CONCLUSIONS

While there are many unknowns associated with modelling the resources needed to scale-up ART, our analysis has suggested a number of key variables which can be used to improve the state of the art of modelling ART. While the magnitude of the effects associated with these variables would be likely to differ in other settings, the variables influencing costs and survival are likely to be generalizable. This is of direct relevance to those concerned about assessing the long-term costs and sustainability of expanded access to ART.

Cost-effectiveness of laboratory monitoring in sub-Saharan Africa: a review of the current literature

As the global community evaluates the unprecedented investment in the scale-up of human immunodeficiency virus (HIV) therapy and considers future investments in HIV care, it is crucial to identify those HIV interventions that maximize the benefit realized from each dollar spent. The use of laboratory monitoring assays--CD4 cell count and HIV RNA level--in decisions about when to initiate and switch antiretroviral therapy may offer substantial clinical benefit, but their economic value remains controversial. Cost-effectiveness analysis can be used to evaluate the value for money of strategies for HIV care, including alternative approaches to laboratory monitoring. Five published cost-effectiveness analyses address the question of CD4 cell count and HIV RNA level monitoring for HIV-infected patients in Africa, with differing conclusions. We describe the use of cost-effectiveness analysis in resource-limited settings and review the cost-effectiveness literature with regard to monitoring the CD4 cell count and HIV RNA level in Africa, highlighting some of the most critical issues in this debate.

Pooled nucleic acid testing to identify antiretroviral treatment failure during HIV infection

BACKGROUND

Pooling strategies have been used to reduce the costs of polymerase chain reaction-based screening for acute HIV infection in populations in which the prevalence of acute infection is low (less than 1%). Only limited research has been done for conditions in which the prevalence of screening positivity is higher (greater than 1%).

METHODS AND RESULTS

We present data on a variety of pooling strategies that incorporate the use of polymerase chain reaction-based quantitative measures to monitor for virologic failure among HIV-infected patients receiving antiretroviral therapy. For a prevalence of virologic failure between 1% and 25%, we demonstrate relative efficiency and accuracy of various strategies. These results could be used to choose the best strategy based on the requirements of individual laboratory and clinical settings such as required turnaround time of results and availability of resources.

CONCLUSIONS

Virologic monitoring during antiretroviral therapy is not currently being performed in many resource-constrained settings largely because of costs. The presented pooling strategies may be used to significantly reduce the cost compared with individual testing, make such monitoring feasible, and limit the development and transmission of HIV drug resistance in resource-constrained settings. They may also be used to design efficient pooling strategies for other settings with quantitative screening measures.

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.

Can we spend our way out of the AIDS epidemic? A world halting AIDS model

Background

There has been a sudden increase in the amount of money donors are willing to spend on the worldwide HIV/AIDS epidemic. Present plans are to hold most of the money in reserve and spend it slowly. However, rapid spending may be the best strategy for halting this disease.

Methods

We develop a mathematical model that predicts eradication or persistence of HIV/AIDS on a world scale. Dividing the world into regions (continents, countries etc), we develop a linear differential equation model of infectives which has the same eradication properties as more complex models.

Results

We show that, even if HIV/AIDS can be eradicated in each region independently, travel/immigration of infectives could still sustain the epidemic. We use a continent-level example to demonstrate that eradication is possible if preventive intervention methods (such as condoms or education) reduced the infection rate to two fifths of what it is currently. We show that, for HIV/AIDS to be eradicated within five years, the total cost would be ≈ $63 billion, which is within the existing $60 billion (plus interest) amount raised by the donor community. However, if this action is spread over a twenty year period, as currently planned, then eradication is no longer possible, due to population growth, and the costs would exceed $90 billion.

Conclusion

Eradication of AIDS is feasible, using the tools that we have currently to hand, but action needs to occur immediately. If not, then HIV/AIDS will race beyond our ability to afford it.

Adult combination antiretroviral therapy in sub-Saharan Africa: lessons from Botswana and future challenges

Numerous national public initiatives offering first-line combination antiretroviral therapy (cART) for HIV infection have commenced in sub-Saharan Africa since 2002. Presently, 2.1 million of an estimated seven million Africans in need of cART are receiving treatment. Analyses from the region report favorable clinical/treatment outcomes and impressive declines in AIDS-related mortality among HIV-1-infected adults and children receiving cART. While immunologic recovery, virologic suppression and cART adherence rates are on par with resource-rich settings, loss to follow-up and high mortality rates, especially within the first 6 months of treatment, remain a significant problem. Over the next decade, cART coverage rates are expected to improve across the region, with attendant increases in healthcare utilization for HIV- and non-HIV-related complications and the need for expanded laboratory and clinical services. Planned and in-progress trials will evaluate the use of cART to prevent primary HIV-1 infection with so-called 'test and treat' expansions of coverage and treatment. Education and training programs as well as patient-retention strategies will need to be strengthened as national cART programs are expanded and more people require lifelong monitoring and care.

Monitoring virologic responses to antiretroviral therapy in HIV-infected adults in Kenya: evaluation of a low-cost viral load assay

Background

A key advantage of monitoring HIV viral load (VL) in persons receiving antiretroviral therapy (ART) is the ability to detect virologic failure before clinical deterioration or resistance occurs. Detection of virologic failure will help clarify the need for enhanced adherence counseling or a change to second- line therapy. Low-cost, locally performable alternates to expensive VL assays are needed where resources are limited.

Methodology/Principal Findings

We monitored the response to 48-week ART in 100 treatment-naïve Kenyan adults using a low-cost VL measurement, the Cavidi reverse transcriptase (RT) assay and gold-standard assays, Roche RNA PCR and Bayer Versant HIV-1 RNA (bDNA) assays. In Altman-Bland plots, the mean difference in viral loads between the three assays was small (<0.5 log₁₀ copies/mL). However, the limits of agreement between the methods exceeded the biologically relevant change of 0.5 log copies/ml. Therefore, the RT assay cannot be used interchangeably with the other assays to monitor individual patients. The RT assay was 100% sensitive in detecting viral loads of ≥400 copies/ml compared to gold-standard assays. After 24 weeks of treatment, viral load measured by the RT assay was undetectable in 95% of 65 patients with undetectable RNA PCR VL (<400 copies/ml), 90% of 67 patients with undetectable bDNA VL, and 96% of 57 patients with undetectable VL in both RNA PCR and bDNA assays. The negative predictive value of the RT assay was 100% compared to either assay; the positive predictive value was 86% compared to RNA PCR and 70% compared to bDNA.

Conclusion

The RT assay compared well with gold standard assays. Our study highlights the importance of not interchanging viral load assays when monitoring an individual patient. Furthermore, the RT assay may be limited by low positive predictive values when used in populations with low prevalence of virologic failure.

Clinical prognostic value of RNA viral load and CD4 cell counts during untreated HIV-1 infection--a quantitative review

Background

The prognostic value of CD4 counts and RNA viral load for identifying treatment need in HIV-infected individuals depends on (a) variation within and among individuals, and (b) relative risks of clinical progression per unit CD4 or RNA difference.

Methodology/Principal Findings

We reviewed these measurements across (a) 30 studies, and (b) 16 cohorts of untreated seropositive adults. Median within-population interquartile ranges were 74,000 copies/mL for RNA with no significant change during the course of infection; and 330 cells/µL for CD4, with a slight proportional increase over infection. Applying measurement and physiological fluctuations observed on chronically infected patients, we estimate that 45% of population-level variation in RNA, and 25% of variation in CD4, were due to within-patient fluctuations. Comparing a patient with RNA at upper 75^th centile with a patient at median RNA, 5-year relative risks were 1.4 (95% CI 1.2–1.7) for AIDS and 1.5 (1.3–1.9) for death, without change over the course of infection. In contrast, for a patient with CD4 count at the lower 75^th centile, relative risks increased from 1.0 at seroconversion to maxima of 6.3 (4.4–8.9) for AIDS and 5.5 (2.7–10.1) for death by year 6, when the population median had fallen to 300 cells/µL. Below 300 cells/µL, prognostic power did not increase, due to a narrower CD4 range.

Conclusions

Findings support the current WHO recommendation (used with clinical criteria) to start antiretroviral treatment in low-income settings at CD4 thresholds of 200–350 cells/µL, without pre-treatment RNA monitoring – while not precluding earlier treatment based on clinical, socio-demographic or public health criteria.

Cost effectiveness of high-risk HPV DNA testing for cervical cancer screening in South Africa

OBJECTIVE

To determine the cost effectiveness of several cervical cancer screening strategies utilizing HPV testing in South Africa.

METHODS

We developed a lifetime Markov model of the costs, quality of life, and survival associated with screening and treating cervical cancer and its precursors. Screening strategies evaluated included: 1) conventional cytology, 2) cytology followed by HPV testing for triage of equivocal cytology, 3) HPV testing, 4) HPV testing followed by cytology for triage of HPV-positive women, and 5) co-screening with cytology and HPV testing. Primary outcome measures included quality-adjusted life-years saved (QALYs), incremental cost-effectiveness ratios, and lifetime risk of cervical cancer. Costs are in 2006 South African Rand (R).

RESULTS

In a cohort of 100,000 women, starting at age 30 and screening once every 10 years reduced the lifetime risk of cervical cancer by 13-52% depending on the screening strategy used, at an incremental cost of R13,000-R42,000 per QALY. When strategies were compared incrementally, cytology with HPV triage was less expensive and more effective than screening using cytology alone. HPV testing with the use of cytology triage was a more effective strategy and costs an additional R42,121 per QALY. HPV testing with colposcopy for HPV-positive women was the next most effective option at an incremental cost of R1541 per QALY. Simultaneous HPV testing and cytology co-screening was the most effective strategy and had an incremental cost of R25,414 per QALY.

CONCLUSIONS

In our model, HPV testing to screen for cervical cancer and its precursors is a cost-effective strategy in South Africa.

Outcomes from monitoring of patients on antiretroviral therapy in resource-limited settings with viral load, CD4 cell count, or clinical observation alone: a computer simulation model

BACKGROUND

In lower-income countries, WHO recommends a population-based approach to antiretroviral treatment with standardised regimens and clinical decision making based on clinical status and, where available CD4 cell count, rather than viral load. Our aim was to study the potential consequences of such monitoring strategies, especially in terms of survival and resistance development.

METHODS

A validated computer simulation model of HIV infection and the effect of antiretroviral therapy was used to compare survival, use of second-line regimens, and development of resistance that result from different strategies-based on viral load, CD4 cell count, or clinical observation alone-for determining when to switch people starting antiretroviral treatment with the WHO-recommended first-line regimen of stavudine, lamivudine, and nevirapine to second-line antiretroviral treatment.

FINDINGS

Over 5 years, the predicted proportion of potential life-years survived was 83% with viral load monitoring (switch when viral load >500 copies per mL), 82% with CD4 cell count monitoring (switch at 50% drop from peak), and 82% with clinical monitoring (switch when two new WHO stage 3 events or a WHO stage 4 event occur). Corresponding values over 20 years were 67%, 64%, and 64%. Findings were robust to variations in model specification in extensive univariable and multivariable sensitivity analyses. Although survival was slightly longer with viral load monitoring, this strategy was not the most cost effective.

INTERPRETATION

For patients on the first-line regimen of stavudine, lamivudine, and nevirapine the benefits of viral load or CD4 cell count monitoring over clinical monitoring alone are modest. Development of cheap and robust versions of these assays is important, but widening access to antiretrovirals-with or without laboratory monitoring-is currently the highest priority.