Amplification-free detection of SARS-CoV-2 with CRISPR-Cas13a and mobile phone microscopy

The December 2019 outbreak of a novel respiratory virus, SARS-CoV-2, has become an ongoing global pandemic due in part to the challenge of identifying symptomatic, asymptomatic, and pre-symptomatic carriers of the virus. CRISPR diagnostics can augment gold-standard PCR-based testing if they can be made rapid, portable, and accurate. Here, we report the development of an amplification-free CRISPR-Cas13a assay for direct detection of SARS-CoV-2 from nasal swab RNA that can be read with a mobile phone microscope. The assay achieved ∼100 copies/μL sensitivity in under 30 min of measurement time and accurately detected pre-extracted RNA from a set of positive clinical samples in under 5 min. We combined crRNAs targeting SARS-CoV-2 RNA to improve sensitivity and specificity and directly quantified viral load using enzyme kinetics. Integrated with a reader device based on a mobile phone, this assay has the potential to enable rapid, low-cost, point-of-care screening for SARS-CoV-2.

Point-of-care HIV viral load in pregnant women without prenatal care: a cost-effectiveness analysis

BACKGROUND

Routine cesarean delivery has been shown to decrease mother-to-child-transmission of HIV in women with high viral load greater than 1000 copies/mL; however, women presenting late in pregnancy may not have viral load results before delivery.

OBJECTIVE

Our study investigated the costs and outcomes of using a point-of-care HIV RNA viral load test to guide delivery compared with routine cesarean delivery for all in the setting of unknown viral load.

STUDY DESIGN

A decision-analytic model was constructed using TreeAge software to compare HIV RNA viral load testing vs routine cesarean delivery for all in a theoretical cohort of 1275 HIV-positive women without prenatal care who presented at term for delivery, the estimated population of HIV-positive women without prenatal care in the United States annually. TreeAge Pro software is used to build decision trees modeling clinical problems and perform cost-effectiveness, sensitivity, and simulation analysis to identify the optimal outcome. The average cost per test was $15.22. To examine the downstream impact of a cesarean delivery and because most childbearing women in the United States will deliver 2 children, we incorporated a second pregnancy and delivery in the model. Primary outcomes were mother-to-child transmission, delivery mode, cesarean delivery-related complications, cost, and quality-adjusted life years. Model inputs were derived from the literature and varied in sensitivity analyses. The cost-effectiveness threshold was $100,000/quality-adjusted life year.

RESULTS

Measuring viral load resulted in more HIV-infected neonates than routine cesarean delivery for all due to viral exposure during more frequent vaginal births in this strategy. There were no observed maternal deaths or differences in cesarean delivery-related complications. Quantifying viral load increased cost by $3,883,371 and decreased quality-adjusted life years by 63 compared with routine cesarean delivery for all. With the threshold set at $100,000/quality-adjusted life year, the viral load test is cost-effective only when the vertical transmission rate in women with high viral load was below 0.68% (baseline: 16.8%) and when the odds ratio of vertical transmission with routine cesarean delivery for all compared with vaginal delivery was above 0.885 (baseline: 0.3).

CONCLUSIONS

For HIV-infected pregnant women without prenatal care, quantifying viral load to guide mode of delivery using a point-of-care test resulted in increased costs and decreased effectiveness when compared with routine cesarean delivery for all, even after including downstream complications of cesarean delivery.

Monitoring viral load for the last mile: what will it cost?

INTRODUCTION

Routine viral load testing is the WHO-recommended method for monitoring HIV-infected patients on ART, and many countries are rapidly scaling up testing capacity at centralized laboratories. Providing testing access to the most remote populations and facilities (the "last mile") is especially challenging. Using a geospatial optimization model, we estimated the incremental costs of accessing the most remote 20% of patients in Zambia by expanding the transportation network required to bring blood samples from ART clinics to centralized laboratories and return results to clinics.

METHODS

The model first optimized a sample transportation network (STN) that can transport 80% of anticipated sample volumes to centralized viral load testing laboratories on a daily or weekly basis, in line with Zambia's 2020 targets. Data incorporated into the model included the location and infrastructure of all health facilities providing ART, location of laboratories, measured distances and drive times between the two, expected future viral load demand by health facility, and local cost estimates. We then continued to expand the modelled STN in 5% increments until 100% of all samples could be collected.

RESULTS AND DISCUSSION

The cost per viral load test when reaching 80% patient volumes using centralized viral load testing was a median of $18.99. With an expanded STN, the incremental cost per test rose to $20.29 for 80% to 85% and $20.52 for 85% to 90%. Above 90% coverage, the incremental cost per test increased substantially to $31.57 for 90% to 95% and $51.95 for 95% to 100%. The high numbers of kilometres driven per sample transported and large number of vehicles needed increase costs dramatically for reaching the clinics that serve the last 5% of patients.

CONCLUSIONS

Providing sample transport services to the most remote clinics in low- and middle-income countries is likely to be cost-prohibitive. Other strategies are needed to reduce the cost and increase the feasibility of making viral load monitoring available to the last 10% of patients. The cost of alternative methods, such as optimal point-of-care viral load equipment placement and usage, dried blood/plasma spot specimen utilization, or use of drones in geographically remote facilities, should be evaluated.

Optimizing viral load testing access for the last mile: Geospatial cost model for point of care instrument placement

INTRODUCTION

Viral load (VL) monitoring programs have been scaled up rapidly, but are now facing the challenge of providing access to the most remote facilities (the "last mile"). For the hardest-to-reach facilities in Zambia, we compared the cost of placing point of care (POC) viral load instruments at or near facilities to the cost of an expanded sample transportation network (STN) to deliver samples to centralized laboratories.

METHODS

We extended a previously described geospatial model for Zambia that first optimized a STN for centralized laboratories for 90% of estimated viral load volumes. Amongst the remaining 10% of volumes, facilities were identified as candidates for POC placement, and then instrument placement was optimized such that access and instrument utilization is maximized. We evaluated the full cost per test under three scenarios: 1) POC placement at all facilities identified for POC; 2)an optimized combination of both on-site POC placement and placement at facilities acting as POC hubs; and 3) integration into the centralized STN to allow use of centralized laboratories.

RESULTS

For the hardest-to-reach facilities, optimal POC placement covered a quarter of HIV-treating facilities. Scenario 2 resulted in a cost per test of $39.58, 6% less than the cost per test of scenario 1, $41.81. This is due to increased POC instrument utilization in scenario 2 where facilities can act as POC hubs. Scenario 3 was the most costly at $53.40 per test, due to high transport costs under the centralized model ($36 per test compared to $12 per test in scenario 2).

CONCLUSIONS

POC VL testing may reduce the costs of expanding access to the hardest-to-reach populations, despite the cost of equipment and low patient volumes. An optimal combination of both on-site placement and the use of POC hubs can reduce the cost per test by 6-35% by reducing transport costs and increasing instrument utilization.

Impact of a borderless sample transport network for scaling up viral load monitoring: results of a geospatial optimization model for Zambia

INTRODUCTION

The World Health Organization recommends viral load (VL) monitoring at six and twelve months and then annually after initiating antiretroviral treatment for HIV. In many African countries, expansion of VL testing has been slow due to a lack of efficient blood sample transportation networks (STN). To assist Zambia in scaling up testing capacity, we modelled an optimal STN to minimize the cost of a national VL STN.

METHODS

The model optimizes a STN in Zambia for the anticipated 1.5 million VL tests that will be needed in 2020, taking into account geography, district political boundaries, and road, laboratory and facility infrastructure. We evaluated all-inclusive STN costs of two alternative scenarios: (1) optimized status quo: each district provides its own weekly or daily sample transport; and (2) optimized borderless STN: ignores district boundaries, provides weekly or daily sample transport, and reaches all Scenario 1 facilities.

RESULTS

Under both scenarios, VL testing coverage would increase to from 10% in 2016 to 91% in 2020. The mean transport cost per VL in Scenario 2 was $2.11 per test (SD $0.28), 52% less than the mean cost/test in Scenario 1, $4.37 (SD $0.69), comprising 10% and 19% of the cost of a VL respectively.

CONCLUSIONS

An efficient STN that optimizes sample transport on the basis of geography and test volume, rather than political boundaries, can cut the cost of sample transport by more than half, providing a cost savings opportunity for countries that face significant resource constraints.

Does Economic Strengthening Improve Viral Suppression Among Adolescents Living with HIV? Results From a Cluster Randomized Trial in Uganda

To assess the effect of a savings-led economic empowerment intervention on viral suppression among adolescents living with HIV. Using data from Suubi + Adherence, a longitudinal, cluster randomized trial in southern Uganda (2012-2017), we examine the effect of the intervention on HIV RNA viral load, dichotomized between undetectable (< 40 copies/ml) and detectable (≥ 40 copies/ml). Cluster-adjusted comparisons of means and proportions were used to descriptively analyze changes in viral load between study arms while multi-level modelling was used to estimate treatment efficacy after adjusting for fixed and random effects. At 24-months post intervention initiation, the proportion of virally suppressed participants in the intervention cohort increased tenfold (Δ_T2-T0 = + 10.0, p = 0.001) relative to the control group (Δ_T2-T0 = + 1.1, p = 0.733). In adjusted mixed models, simple main effects tests identified significantly lower odds of intervention adolescents having a detectable viral load at both 12- and 24-months. Interventions addressing economic insecurity have the potential to bolster health outcomes, such as HIV viral suppression, by improving ART adherence among vulnerable adolescents living in low-resource environments. Further research and policy dialogue on the intersections of financial security and HIV treatment are warranted.

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.

The case for viral load testing in adolescents in resource-limited settings

INTRODUCTION

The success of HIV treatment programmes globally has resulted in children with perinatally acquired HIV reaching adolescence in large numbers. The number of adolescents living with HIV is growing further due to persisting high HIV incidence rates among adolescents in low- and middle-income settings, particularly in sub-Saharan Africa. Although expanding access to HIV viral load monitoring is necessary to achieve the 90-90-90 targets across the HIV care continuum, implementation is incomplete. We discuss the rationale for prioritizing viral load monitoring among adolescents and the associated challenges.

DISCUSSION

Adolescents with HIV are a complex group to treat successfully due to extensive exposure to antiretroviral therapy for those with perinatally acquired HIV and the challenges in sustained medication adherence in this age group. Given the high risk of treatment failure among adolescents and the limited drug regimens available in limited resource settings, HIV viral load monitoring in adolescents could prevent unnecessary and costly switches to second-line therapy in virologically suppressed adolescents. Because adolescents living with HIV may be heavily treatment experienced, have suboptimal treatment adherence, or may be on second or even third-line therapy, viral load testing would allow clinicians to make informed decisions about increased counselling and support for adolescents together with the need to maintain or switch therapeutic regimens.

CONCLUSIONS

Given scarce resources, prioritization of viral load testing among groups with a high risk of virological failure may be required. Adolescents have disproportionately high rates of virological failure, and targeting this age group for viral load monitoring may provide valuable lessons to inform broader scale-up.

Scale-up of Routine Viral Load Testing in Resource-Poor Settings: Current and Future Implementation Challenges

Despite immense progress in antiretroviral therapy (ART) scale-up, many people still lack access to basic standards of care, with our ability to meet the Joint United Nations Programme on HIV/AIDS 90-90-90 treatment targets for HIV/AIDS dependent on dramatic improvements in diagnostics. The World Health Organization recommends routine monitoring of ART effectiveness using viral load (VL) testing at 6 months and every 12 months, to monitor treatment adherence and minimize failure, and will publish its VL toolkit later this year. However, the cost and complexity of VL is preventing scale-up beyond developed countries and there is a lack of awareness among clinicians as to the long-term patient benefits and its role in prolonging the longevity of treatment programs. With developments in this diagnostic field rapidly evolving-including the recent improvements for accurately using dried blood spots and the imminent appearance to the market of point-of-care technologies offering decentralized diagnosis-we describe current barriers to VL testing in resource-limited settings. Effective scale-up can be achieved through health system and laboratory system strengthening and test price reductions, as well as tackling multiple programmatic and funding challenges.

Cost-effectiveness of testing hepatitis B-positive pregnant women for hepatitis B e antigen or viral load

OBJECTIVE

To estimate the cost-effectiveness of testing pregnant women with hepatitis B (hepatitis B surface antigen [HBsAg]-positive) for hepatitis B e antigen (HBeAg) or hepatitis B virus (HBV) DNA, and administering maternal antiviral prophylaxis if indicated, to decrease breakthrough perinatal HBV transmission from the U.S. health care perspective.

METHODS

A Markov decision model was constructed for a 2010 birth cohort of 4 million neonates to estimate the cost-effectiveness of two strategies: testing HBsAg-positive pregnant women for 1) HBeAg or 2) HBV load. Maternal antiviral prophylaxis is given from 28 weeks of gestation through 4 weeks postpartum when HBeAg is positive or HBV load is high (10 copies/mL or greater). These strategies were compared with the current recommendation. All neonates born to HBsAg-positive women received recommended active-passive immunoprophylaxis. Effects were measured in quality-adjusted life-years (QALYs) and all costs were in 2010 U.S. dollars.

RESULTS

The HBeAg testing strategy saved $3.3 million and 3,080 QALYs and prevented 486 chronic HBV infections compared with the current recommendation. The HBV load testing strategy cost $3 million more than current recommendation, saved 2,080 QALYs, and prevented 324 chronic infections with an incremental cost-effectiveness ratio of $1,583 per QALY saved compared with the current recommendations. The results remained robust over a wide range of assumptions.

CONCLUSION

Testing HBsAg-positive pregnant women for HBeAg or HBV load followed by maternal antiviral prophylaxis if HBeAg-positive or high viral load to reduce perinatal hepatitis B transmission in the United States is cost-effective.

Effect of management strategies and clinical status on costs of care for advanced HIV

OBJECTIVES

To determine the association between preexisting characteristics and current health and the cost of different types of advanced human immunodeficiency virus (HIV) care.

METHODS

Treatment-experienced patients failing highly active antiretroviral treatment (ART) in the United States, Canada, and the United Kingdom were factorial randomized to an antiretroviral-free period and ART intensification. Cost was estimated by multiplying patient-reported utilization by a unit cost.

RESULTS

A total of 367 participants were followed for a mean of 15.3 quarters (range 1-26). Medication accounted for most (61.8%) of the $26,832 annual cost. Cost averaged $4147 per quarter for ART, $1981 for inpatient care, $580 for outpatient care, and $346 for other medications. Cost for inpatient stays, outpatient visits, and other medications was 171% higher (P <.01) and cost of ART was 32% lower (P <.01) when cluster of differentiation 4 (CD4) count was <50 cells/μL compared with periods when CD4 count was >200 cells/μL. Some baseline characteristics, including low CD4 count, high viral load, and HIV from injection drug use with hepatitis C coinfection, had a sustained effect on cost.

CONCLUSIONS

The association between health status and cost depended on the type of care. Indicators of poor health were associated with higher inpatient and concomitant medication costs and lower cost for ART medication. Although ART has supplanted hospitalization as the most important cost in HIV care, some patients continue to incur high hospitalization costs in periods when they are using less ART. The cost of interventions to improve the use of ART might be offset by the reduction of other costs.

How do different eligibility guidelines for antiretroviral therapy affect the cost-effectiveness of routine viral load testing in sub-Saharan Africa?

BACKGROUND

Increased eligibility guidelines of antiretroviral therapy (ART) may lead to greater routine viral load monitoring. However, in resource-constrained settings, the additional resources required by greater routine viral load monitoring may impair ability to comply with expanded eligibility guidelines for ART.

OBJECTIVE

We use a published validated computer simulation of the HIV epidemic in East African countries (expanded to include transmission as well as disease progression) to evaluate the cost-effectiveness of routine viral load monitoring.

METHODS

We explored alternative scenarios regarding cost, frequency, and switching threshold of routine viral load monitoring (including every 6 or every 12 months; and switching thresholds of 1000, or 10 000 copies/ml), as well as alternative scenarios regarding ART initiation (200, 350, 500  cells/μl, and no CD4 cell threshold). For each ART initiation strategy, we sought to identify the viral load monitoring strategy at which the incremental cost-effectiveness ratio (ICER) of more frequent routine viral load testing became more favorable than the ICER of more expansive ART eligibility. Cost inputs were based on data provided by the Academic Model Providing Access to Healthcare (AMPATH), and disease progression inputs were based on prior published work. We used a discount rate of 3%, a time horizon of 20 years, and a payer perspective.

RESULTS

Across a wide range of scenarios, and even when considering the beneficial effect of virological monitoring at reducing HIV transmission, earlier ART initiation conferred far greater health benefits for resources spent than routine virological testing, with ICERs of approximately $1000 to $2000 for earlier ART initiation, versus ICERs of approximately $5000 to $25 000 for routine virological monitoring. ICERs of viral load testing were insensitive to the cost of the viral load test, because most of the costs originated from the downstream higher costs of later regimens. ICERs of viral load testing were very sensitive to the relative cost of second-line compared with first-line regimens, assuming favorable value when the costs of these regimens were equal.

CONCLUSION

If all HIV patients are not yet treated with ART starting at 500  cells/μl and costs of second regimens remain substantially more expensive than first-line regimens, resources would buy more population health if they are spent on earlier ART rather than being spent on routine virological testing.

A study of financial incentives to reduce plasma HIV RNA among patients in care

The role of financial incentives in HIV care is not well studied. We conducted a single-site study of monetary incentives for viral load suppression, using each patient as his own control. The incentive size ($100/quarter) was designed to be cost-neutral, offsetting estimated downstream costs averted through reduced HIV transmission. Feasibility outcomes were clinic workflow, patient acceptability, and patient comprehension. Although the study was not powered for effectiveness, we also analyzed viral load suppression. Of 80 eligible patients, 77 consented, and 69 had 12 month follow-up. Feasibility outcomes showed minimal impact on patient workflow, near-unanimous patient acceptability, and satisfactory patient comprehension. Among individuals with detectable viral loads pre-intervention, the proportion of undetectable viral load tests increased from 57 to 69 % before versus after the intervention. It is feasible to use financial incentives to reward ART adherence, and to specify the incentive by requiring cost-neutrality and targeting biological outcomes.

A one step real-time RT-PCR assay for the quantitation of Wheat yellow mosaic virus (WYMV)

BACKGROUND

Wheat yellow mosaic virus (WYMV) is an important pathogen in China and other countries. It is the member of the genus Bymovirus and transmitted primarily by Polymyxa graminis. The incidence of wheat infections in endemic areas has risen in recent years. Prompt and dependable identification of WYMV is a critical component of response to suspect cases.

METHODS

In this study, a one step real-time RT-PCR, followed by standard curve analysis for the detection and identification of WYMV, was developed. Two reference genes, 18s RNA and β-actin were selected in order to adjust the veracity of the real-time RT-PCR assay.

RESULTS

We developed a one-step Taqman-based real-time quantitative RT-PCR (RT-qPCR) assay targeting the conserved region of the 879 bp long full-length WYMV coat protein gene. The accuracy of normalized data was analyzed along with appropriate internal control genes: β-actin and 18s rRNA which were included in detecting of WYMV-infected wheat leaf tissues. The detectable end point sensitivity in RT-qPCR assay was reaching the minimum limit of the quantitative assay and the measurable copy numbers were about 30 at 10⁶-fold dilution of total RNA. This value was close to 10⁴-fold more sensitive than that of indirect enzyme-linked immunosorbent assay. More positive samples were detected by RT-qPCR assay than gel-based RT-PCR when detecting the suspected samples collected from 8 regions of China. Based on presented results, RT-qPCR will provide a valuable method for the quantitative detection of WYMV.

CONCLUSIONS

The Taqman-based RT-qPCR assay is a faster, simpler, more sensitive and less expensive procedure for detection and quantification of WYMV than other currently used methods.

Low-cost assays for monitoring HIV infected individuals in resource-limited settings

Use of a combination of CD4 counts and HIV viral load testing in the management of antiretroviral therapy (ART) provides higher prognostic estimation of the risk of disease progression than does the use of either test alone. The standard methods to monitor HIV infection are flow cytometry based for CD4+ T cell count and molecular assays to quantify plasma viral load of HIV. Commercial assays have been routinely used in developed countries to monitor ART. However, these assays require expensive equipment and reagents, well trained operators, and established laboratory infrastructure. These requirements restrict their use in resource-limited settings where people are most afflicted with the HIV-1 epidemic. With the advent of low-cost and/or low-tech alternatives, the possibility of implementing CD4 count and viral load testing in the management of ART in resource-limited settings is increasing. However, an appropriate validation should have been done before putting them to use for patient testing.

CD4 cell count and viral load monitoring in patients undergoing antiretroviral therapy in Uganda: cost effectiveness study

OBJECTIVE

To examine the cost and cost effectiveness of quarterly CD4 cell count and viral load monitoring among patients taking antiretroviral therapy (ART).

DESIGN

Cost effectiveness study.

SETTING

A randomised trial in a home based ART programme in Tororo, Uganda.

PARTICIPANTS

People with HIV who were members of the AIDS Support Organisation and had CD4 cell counts <250 × 10(6) cells/L or World Health Organization stage 3 or 4 disease.

MAIN OUTCOME MEASURES

Outcomes calculated for the study period and projected 15 years into the future included costs, disability adjusted life years (DALYs), and incremental cost effectiveness ratios (ICER; $ per DALY averted). Cost inputs were based on the trial and other sources. Clinical inputs derived from the trial; in the base case, we assumed that point estimates reflected true differences even if non-significant. We conducted univariate and multivariate sensitivity analyses.

INTERVENTIONS

Three monitoring strategies: clinical monitoring with quarterly CD4 cell counts and viral load measurement (clinical/CD4/viral load); clinical monitoring and quarterly CD4 counts (clinical/CD4); and clinical monitoring alone.

RESULTS

With the intention to treat (ITT) results per 100 individuals starting ART, we found that clinical/CD4 monitoring compared with clinical monitoring alone increases costs by $20,458 (£12,780, €14,707) and averts 117.3 DALYs (ICER = $174 per DALY). Clinical/CD4/viral load monitoring compared with clinical/CD4 monitoring adds $142,458, and averts 27.5 DALYs ($5181 per DALY). The superior ICER for clinical/CD4 monitoring is robust to uncertainties in input values, and that strategy is dominant (less expensive and more effective) compared with clinical/CD4/viral load monitoring in one quarter of simulations. If clinical inputs are based on the as treated analysis starting at 90 days (after laboratory monitoring was initiated), then clinical/CD4/viral load monitoring is dominated by other strategies.

CONCLUSIONS

Based on this trial, compared with clinical monitoring alone, monitoring of routine CD4 cell count is considerably more cost effective than additionally including routine viral load testing in the monitoring strategy and is more cost effective than ART.

Measures of site resourcing predict virologic suppression, immunologic response and HIV disease progression following highly active antiretroviral therapy (HAART) in the TREAT Asia HIV Observational Database (TAHOD)

OBJECTIVES

Surrogate markers of HIV disease progression are HIV RNA in plasma viral load (VL) and CD4 cell count (immune function). Despite improved international access to antiretrovirals, surrogate marker diagnostics are not routinely available in resource-limited settings. Therefore, the objective was to assess effects of economic and diagnostic resourcing on patient treatment outcomes.

METHODS

Analyses were based on 2333 patients initiating highly active antiretroviral therapy (HAART) from 2000 onwards. Sites were categorized by World Bank country income criteria (high/low) and annual frequency of VL (> or = 3, 1-2 or <1) or CD4 (> or = 3 or <3) testing. Endpoints were time to AIDS/death and change in CD4 cell count and VL suppression (<400 HIV-1 RNA copies/mL) at 12 months. Demographics, Centers for Disease Control and Prevention (CDC) classification, baseline VL/CD4 cell counts, hepatitis B/C coinfections and HAART regimen were covariates. Time to AIDS/death was analysed by proportional hazards models. CD4 and VL endpoints were analysed using linear and logistic regression, respectively.

RESULTS

Increased disease progression was associated with site-reported VL testing less than once per year [hazard ratio (HR)=1.4; P=0.032], severely symptomatic HIV infection (HR=1.4; P=0.003) and hepatitis C virus coinfection (HR=1.8; P=0.011). A total of 1120 patients (48.2%) had change in CD4 cell count data. Smaller increases were associated with older age (P<0.001) and 'Other' HIV source exposures, including injecting drug use and blood products (P=0.043). A total of 785 patients (33.7%) contributed to the VL suppression analyses. Patients from sites with VL testing less than once per year [odds ratio (OR)=0.30; P<0.001] and reporting 'Other' HIV exposures experienced reduced suppression (OR=0.28; P<0.001).

CONCLUSION

Low measures of site resourcing were associated with less favourable patient outcomes, including a 35% increase in disease progression in patients from sites with VL testing less than once per year.

The impact of disease stage on direct medical costs of HIV management: a review of the international literature

The global prevalence of HIV infection continues to grow, as a result of increasing incidence in some countries and improved survival where highly active antiretroviral therapy (HAART) is available. Growing healthcare expenditure and shifts in the types of medical resources used have created a greater need for accurate information on the costs of treatment. The objectives of this review were to compare published estimates of direct medical costs for treating HIV and to determine the impact of disease stage on such costs, based on CD4 cell count and plasma viral load. A literature review was conducted to identify studies meeting prespecified criteria for information content, including an original estimate of the direct medical costs of treating an HIV-infected individual, stratified based on markers of disease progression. Three unpublished cost-of-care studies were also included, which were applied in the economic analyses published in this supplement. A two-step procedure was used to convert costs into a common price year (2004) using country-specific health expenditure inflators and, to account for differences in currency, using health-specific purchasing power parities to express all cost estimates in US dollars. In all nine studies meeting the eligibility criteria, infected individuals were followed longitudinally and a 'bottom-up' approach was used to estimate costs. The same patterns were observed in all studies: the lowest CD4 categories had the highest cost; there was a sharp decrease in costs as CD4 cell counts rose towards 100 cells/mm³; and there was a more gradual decline in costs as CD4 cell counts rose above 100 cells/mm³. In the single study reporting cost according to viral load, it was shown that higher plasma viral load level (> 100,000 HIV-RNA copies/mL) was associated with higher costs of care. The results demonstrate that the cost of treating HIV disease increases with disease progression, particularly at CD4 cell counts below 100 cells/mm³. The suggestion that costs increase as the plasma viral load rises needs independent verification. This review of the literature further suggests that publicly available information on the cost of HAART by disease stage is inadequate. To address the information gap, multiple stakeholders (governments, pharmaceutical industry, private insurers and non-governmental organizations) have begun to establish and support an independent, high quality and standardized multicountry data collection for evaluating the cost of HIV management. An accurate, representative and relevant cost-estimate data resource would provide a valuable asset to healthcare planners that may lead to improved policy and decision-making in managing the HIV epidemic.

Modelling the budget impact of darunavir in the treatment of highly treatment-experienced, HIV-infected adults in France

BACKGROUND

A key element for payers in the assessment of the economic profile of a medication is its anticipated impact on the evolution of healthcare budgets.

OBJECTIVES

To forecast the impact of the use of darunavir with low-dose ritonavir 600/100 mg twice a day (bid) in highly treatment-experienced, HIV-infected adults who have failed one or more protease inhibitor (PI)-containing regimen on the budget of the French Sickness Fund (French healthcare system) over a 3-year time horizon.

METHODS

A transition state model based on disease severity was developed that compared the evolution of antiretroviral and non-antiretroviral-related direct costs of care in the target population over 3 years (2007-2009) under two scenarios: (1) darunavir enters the French market in year 1; (2) darunavir is not available to the target population during 2007-2009. Model inputs were derived from a targeted analysis of the French hospital database in HIV, the darunavir POWER 1 and 2 trials and other relevant clinical studies.

RESULTS

In the scenario where darunavir was available from year 1, the proportion of patients in the lower, more costly CD4 cell count strata (≤ 100 cells per mm³) was consistently lower than in the scenario without darunavir in each year of the model (17.0% vs 19.2%, 13.9% vs 18.3% and 10.8% vs 16.8% for years 1, 2 and 3, respectively). As a result, over the entire 3-year period, the net increase of antiretroviral drug costs (+ 5.6 million Euros; €), resulting from the substitution of older, cheaper PIs by darunavir, is expected to be fully compensated by savings in hospitalization costs (€-9.7 million) and expenditures for other HIV-related (non-antiretroviral) medications (€-7.3 million), leading to a net saving of €11.4 million or 2.9% of the total budget in the scenario without darunavir. Various sensitivity analyses confirmed these projected savings.

CONCLUSION

The use of darunavir/ritonavir (DRV/r) 600/100 mg bid, in combination with other antiretroviral agents, in highly pre-treated, HIV-infected adults who have failed one or more PI-containing highly active antiretroviral therapy regimen is not expected to increase the budget of the French healthcare system, in comparison with a scenario without darunavir. Further research is needed to estimate the budget impact of the use of DRV/r in less treatment-experienced, HIV-infected individuals in France.

Costs to achieve undetectable HIV RNA with darunavir-containing highly active antiretroviral therapy in highly pretreated patients: the POWER experience

BACKGROUND

Very few studies have evaluated the cost of highly active antiretroviral therapy (HAART) per successful treatment in HIV-infected patients.

OBJECTIVES

To evaluate the cost of achieving undetectable plasma HIV-RNA levels in highly treatment-experienced, HIV-1-infected adults receiving darunavir/ritonavir (DRV/r 600 mg/100 mg twice a day) or control protease inhibitor (PI)-based HAART.

METHODS

The mean annual per-patient cost of DRV/r and control PI-based HAART was determined from the proportional use of antiretroviral agents in the DRV/r and control PI arms of the pooled POWER 1 and 2 trials, applying drug acquisition costs for 13 healthcare settings. The mean annual cost per patient of achieving undetectable plasma HIV-RNA levels (<50 copies/mL) was calculated by dividing the cost of each treatment by the proportion of patients with undetectable plasma HIV-RNA levels after 48 weeks in the DRV/r (45%) and control PI (10%) arms of the POWER trials.

RESULTS

Whereas absolute costs of treatment were 1-19% higher with DRV/r versus control PI-based HAART depending on the healthcare setting, the mean annual per-patient cost of achieving undetectable plasma HIV-RNA levels was 73-78% lower. These cost savings were maintained in the sensitivity analyses, adjusting for control PI and enfuvirtide use, and the number of active drugs in the background regimen. The incremental annual cost per additional patient achieving undetectable plasma HIV-RNA levels with DRV/r versus control PI-based HAART in POWER 1 and 2 (£4148) compared favourably with that determined for enfuvirtide (£137, 740; TORO trials) and tipranavir/ritonavir (£32,176; RESIST) versus control therapy.

CONCLUSIONS

DRV/r-based HAART provided consistent reductions in the cost of achieving undetectable plasma HIV-RNA levels compared with control PI-based therapy in highly treatment-experienced patients across various healthcare settings. The incremental cost per additional patient achieving undetectable plasma HIV-RNA levels with DRV/r versus control PI-based HAART was also lower than that calculated for other treatment options in this population. These results suggest that DRV/r is an economically viable option for highly treatment-experienced patients.

US cost effectiveness of darunavir/ritonavir 600/100 mg bid in treatment-experienced, HIV-infected adults with evidence of protease inhibitor resistance included in the TITAN Trial

INTRODUCTION

The phase III TITAN trial evaluated the use of darunavir with low-dose ritonavir (DRV/r) 600/100 mg twice daily (bid) compared with lopinavir with low-dose ritonavir (LPV/r) in treatment-experienced, lopinavir-naive patients. This study estimates the cost effectiveness of DRV/r from a US societal perspective when compared with LPV/r in treatment-experienced patients with a profile similar to those TITAN patients who had one or more International AIDS Society - USA (IAS-USA) primary protease inhibitor (PI) resistance-associated mutations (RAMs) at baseline. This population had less advanced HIV disease and a broader range of previous PI exposure/failure (0 - ≥ 2 PIs) at enrollment than those in the darunavir phase IIb POWER trials.

METHODS

An existing Markov model containing six health states defined by CD4 cell count range (>500, 351-500, 201-350, 101-200, 51-100 and 0-50 cells/mm³) and an absorbing state of death was adapted. Baseline demographics, CD4 cell count distribution and antiretroviral drug usage, virological response (at week 24), and immunological response estimates and matching transition probabilities were based on data collected directly from the one or more IAS-USA PI mutation subpopulation during the first 48 weeks of the TITAN trial, as well as from published literature. Patients were assumed to switch to a regimen containing tipranavir plus an optimized background regimen after treatment failure. For each CD4 cell count range or health state, the utility values, HIV and non-HIV-related mortality rates, and non-antiretroviral-related cost of HIV care estimates were derived from published literature. Unit costs were derived from official local sources. A lifetime horizon was taken in the base-case analysis.

RESULTS

The base-case analysis predicted discounted quality-adjusted survival gains of 0.493 quality-adjusted life-years (QALYs) for DRV/r compared with LPV/r, resulting in an incremental cost-effectiveness ratio (ICER) of US$23,057 per QALY gained over a lifetime horizon. Probabilistic sensitivity analysis indicated a 0.754 probability of an ICER below the threshold of US$50,000 per QALY gained. DRV/r remained cost effective over all parameter ranges tested in extensive one-way sensitivity analyses and variability analyses, which examined the impact of input parameter uncertainty and changes in model assumptions and treatment patterns, respectively. Shortening the model time horizon had the largest impact on the ICER, reducing it most notably to US$4919 with a 10-year time horizon.

CONCLUSION

From a US societal perspective and based on an analysis of the patients with primary IAS-USA PI RAMs enrolled in the darunavir phase III TITAN trial, a highly active antiretroviral therapy (HAART) regimen containing DRV/r 600/100 mg bid is estimated to be a cost-effective therapy when compared with a HAART regimen containing LPV/r, for the management of treatment-experienced, PI-resistant, HIV-infected adults with a broad range of previous PI use/failure.

Cost effectiveness of darunavir/ritonavir 600/100 mg bid in treatment-experienced, lopinavir-naive, protease inhibitor-resistant, HIV-infected adults in Belgium, Italy, Sweden and the UK

BACKGROUND

Using data from the phase IIb POWER trials, darunavir boosted with low-dose ritonavir (DRV/r; 600/100 mg twice daily; bid)-based highly active antiretroviral therapy (HAART) was shown to be significantly more efficacious and cost effective than other protease inhibitor (PI)-based therapy in highly treatment-experienced, HIV-1-infected adults. Furthermore, in the phase III TITAN trial (TMC114-C214), DRV/r 600/100 mg bid-based HAART generated a superior 48-week virological response rate compared with standard-of-care lopinavir/ritonavir (LPV/r; 400/100 mg bid)-based therapy in treatment-experienced, lopinavir-naive patients, and in particular those with one or more International AIDS Society - USA (IAS-USA) primary PI resistance-associated mutations at baseline. These patients had a broader degree of previous PI use/failure (0 - ≥ 2) than the POWER patients.

OBJECTIVES

To determine whether DRV/r 600/100 mg bid-based HAART is cost effective compared with LPV/r-based therapy, from the perspective of Belgian, Italian, Swedish and UK reimbursement authorities, when used in treatment-experienced patients similar to TITAN patients with one or more IAS-USA primary PI mutations at baseline.

METHODS

An existing Markov model containing health states defined by CD4 cell count ranges (>500, 351-500, 201-350, 101-200, 51-100 and 0-50 cells/mm³) and an absorbing state of death was adapted for use in the above-mentioned healthcare settings. Baseline demographics, CD4 cell count distribution, antiretroviral drug usage, virological/immunological response rates and matching transition probabilities were based on data collected during the first 48 weeks of therapy in the modelled subgroup of TITAN patients and the published literature. After treatment failure, patients were assumed to switch to a follow-on combination regimen. For each health state, utility values and mortality rates were obtained from the published literature. Data from local observational studies (Belgium, Sweden and Italy) or the published literature (UK) were used to determine resource-use patterns and costs associated with each CD4 cell count range. Unit costs were derived from official local sources; a lifetime horizon was taken and discount rates were chosen based on local guidelines.

RESULTS

The base-case analysis predicted quality-adjusted life year (QALY) gains of 0.785 in Belgium, 0.608 in Italy, 0.584 in Sweden and 0.550 in the UK when DRV/r-based therapy was used instead of LPV/r-based treatment. The estimated base-case incremental cost-effectiveness ratios (ICERs) were €6964/QALY gained in Belgium, €9277/QALY gained in Italy, €6868 (SEK69,687)/QALY gained in Sweden and €14,778 (£12 612)/QALY gained in the UK. Assuming a threshold of €30,000/QALY gained, DRV/r-based therapy remained cost effective over most parameter ranges tested in extensive one-way sensitivity analyses. The variation of immunological response rates and the time horizon were identified as important drivers of cost effectiveness. Probabilistic sensitivity analysis revealed a greater than 70% probability of achieving an ICER below this threshold in all four healthcare settings.

CONCLUSION

From the perspective of Belgian, Italian, Swedish and UK payers, DRV/r 600/100 mg bid-based HAART is predicted to be cost effective compared with LPV/r 400/100 mg bid-based therapy, when used to manage treatment experienced, lopinavir-naive, PI-resistant, HIV-infected adults with a broad range of previous PI use/failure.

A reverse transcriptase assay for early diagnosis of infant HIV infection in resource-limited settings

Early diagnosis of pediatric HIV infection is confounded by persistence of maternal antibodies until 18 months, necessitating the use of expensive assays such as HIV-1 DNA PCR, an untenable option in resource-limited settings. This is the first report of a low-cost, commercial, reverse transcriptase (RT) assay for the diagnosis of HIV-1 infection in infants. RT assays were performed on 42 samples from 30 HIV-exposed Kenyan infants under 15 months of age. When correlated with serologic testing conducted after 18 months, the sensitivity, specificity, positive and negative predictive values of the RT assay were 92%, 93%, 87% and 96%. A low-cost assay for infant HIV diagnosis is urgently needed, and these results merit further evaluation.

Evaluation of two commercially available alternatives for HIV-1 viral load testing in resource-limited settings

There is an urgent need for low-cost assays for HIV-1 quantitation to ensure adequate follow-up of HIV-infected patients on antiretroviral therapy (ART) in resource-limited countries. Two low-cost viral load assays are evaluated, a reverse transcriptase activity assay (ExavirLoad v2, Cavidi) and a real-time reverse transcriptase PCR assay (Generic HIV viral load, Biocentric). Both tests were compared with the ultrasensitive HIV Amplicor Monitor assay. Samples were collected in Mombasa, Kenya, from 20 HIV-1 seronegative and 150 HIV-1 seropositive individuals of whom 50 received antiretroviral treatment (ART). The ExavirLoad and the Generic HIV viral load assay were performed in a local laboratory in Mombasa, the Amplicor Monitor assay (version 1.5, Roche Diagnostics) was performed in Ghent, Belgium. ExavirLoad and Generic HIV viral load reached a sensitivity of 98.3% and 100% and a specificity of 80.0% and 90.0%, respectively. Linear regression analyses revealed good correlations between the Amplicor Monitor and the Generic HIV viral load (r=0.935, p<0.001) with high accuracy (100.1%), good precision (5.5%) and a low percent similarity coefficient of variation (5.4%). Bland-Altman analysis found 95% of the samples within clinically acceptable limits of agreement (-1.19 to 0.87logcopies/ml). Although, the ExavirLoad also showed a good linear correlation with the Amplicor Monitor (r=0.901, p<0.001), a problem with false positive results was more significant. The cost per test remains relatively high (US$ 30 for ExavirLoad and US$ 20 for the Generic HIV viral load). Hence, false positive results and the need for an expensive PCR instrument for the Generic HIV viral load assays still limit the implementation of these tests in less equipped, less experienced laboratories.

Cost to achieve an undetectable viral load using recommended antiretroviral regimens

PURPOSE

The April 2005 Guidelines for the Use of Antiretroviral Agents in HIV-Infected Adults and Adolescents recommended 9 regimens to be combined with 2 nucleoside reverse transcriptase inhibitors (NRTIs). These regimens are effective in lowering viral load but are expensive. This study aimed to determine the cost for each regimen to achieve an undetectable viral load.

METHOD

52 clinical trials were reviewed. The outcome measure was cost per undetectable patient, C/PU, where C = cost of a drug, and PU = percent of patients with undetectable viral loads.

RESULTS

For 30 weeks, cost per undetectable (<400 copies/mL) ranged from 4,416 dollars (efavirenz) to 23,110 dollars (nelfinavir); for 42 weeks, the range was 5,729 dollars (efavirenz) to 24,071 dollars (indinavir/ritonavir); for 60 weeks, it ranged from 9,535 dollars (efavirenz) to 26,829 dollars (fosamprenavir); and for 84 weeks, it ranged from 12,203 dollars (efavirenz) to 22,960 dollars (nelfinavir). For <50 copies/mL, at 30 weeks the range was from 7,140 dollars (efavirenz) to 17,548 dollars (atazanavir); for 42 weeks, it ranged from 9,849 dollars (lopinavir/ritonavir) to 13,181 dollars (nelfinavir); for 60 weeks, it ranged from 8,702 dollars (nevirapine) to 36,034 dollars (atazanavir); and for 84 weeks, it ranged from 15,660 dollars (efavirenz) to 29,177 dollars (indinavir/ritonavir).

CONCLUSION

Efavirenz's low price and high effectiveness make it the least expensive means of achieving an undetectable viral load.

The measurement of HIV-1 viral load in resource-limited settings: how and where?

There is an urgent need for low-cost, simple, and accurate human immunodeficiency virus type 1 (HIV-1) viral load monitoring technologies in resource-limited settings, particularly at the time of the scaling-up of first and second-line highly active antiretroviral therapies. This review describes the main characteristics and advantages/ disadvantages of three alternative HIV-1 viral load methods currently evaluated and used in developing countries, i.e., the Ultra p24 antigen assay, the ExaVir Load reverse transcriptase activity test, and 'home-made' real-time PCR HIV-1 RNA techniques. This review discusses clinical results obtained with these three technologies in terms of correlation with commercial HIV-1 RNA assays, the impact of HIV-1 genetic diversity on quantification, as well as their usefulness for both the early diagnosis of pediatric HIV-1 infection and monitoring of highly active antiretroviral therapy efficiency. In addition, different strategies for HIV-1 viral load monitoring are discussed according to laboratory facilities in resource-constrained settings.

Evaluation of a low cost reverse transcriptase assay for plasma HIV-1 viral load monitoring

We evaluated a low cost manual reverse transcriptase assay (ExaVir Load V.1 and V.2; Cavidi Tech AB) against commercially available HIV RNA assays that quantify viral load to assess its suitability for use in resource-constrained settings. Frozen plasma samples previously tested for RNA by RT-PCR (Roche Diagnostics) and bDNA (Bayer Diagnostics) were retested for RT activity. Text sequence obtained from HIV genotype analysis was submitted to the Stanford HIV Resistance Database V.3.9 and were examined for resistant virus. Detectable RT was present in 98% of samples (V.1; n=127) and in 95% of samples (V.2; n=69) with RNA >10,000 and >1,000 copies/ml respectively. Positive association was found between the log10 RNA copies/ml and log10 RT copies/ml equivalents variables using Pearson's correlation (V.1: r=0.89, n=189; V.2: r=0.89, n=85). The RT activity over time closely followed the trend for RNA levels in samples from 10 HIV seropositive patients with progressive disease. A strong association between RT and RNA was also found with paired samples from 19 patients taken at initiation or change of antiretroviral therapy and again within 2 months. Current (n=40) or no (n=119) exposure to efavirenz therapy had no effect on RT assay performance despite efavirenz binding tightly to the RT enzyme. Samples that demonstrated resistance to the non-nucleoside RT inhibitors (n=112) had a decrease in RT of 0.20 log10 indicating a possible decrease in RT fitness. The RT assay showed good association with current molecular assays, and V.2 is sufficiently sensitive for monitoring HIV viral load in resource-constrained settings.

Health care industries' perspective of viral load assays: the VERSANT HIV-1 RNA 3.0 assay

This article will compare the VERSANT HIV-1 RNA 3.0 (bDNA 3.0) assay with other HIV-1 viral load assays, particularly the AMPLICOR HIV-1 MONITOR (Amplicor 1.5), the industry standard. The discussion will cover the history of viral load assay development and challenges to the field. It will finish with a description of the evolving markets for viral load assays in the developing world and the impact of variations in the different assays on their ability to reach those markets and patient populations.