The cost-effectiveness of preventing AIDS-related opportunistic infections

Virological, serological and clinical outcomes in chronic hepatitis B virus infection: development and validation of the HEPA-B simulation model

OBJECTIVES

Detailed simulation models are needed to assess strategies for prevention and treatment of hepatitis B virus (HBV) infection, the world's leading cause of liver disease. We sought to develop and validate a simulation model of chronic HBV that incorporates virological, serological and clinical outcomes.

METHODS

We developed a novel Monte Carlo simulation model (the HEPA-B Model) detailing the natural history of chronic HBV. We parameterised the model with epidemiological data from the Western Pacific and sub-Saharan Africa. We simulated the evolution of HBV DNA, 'e' antigen (HBeAg) and surface antigen (HBsAg). We projected incidence of HBeAg loss, HBsAg loss, cirrhosis, hepatocellular carcinoma (HCC) and death over 10-year and lifetime horizons. We stratified outcomes by five HBV DNA categories at the time of HBeAg loss, ranging from HBV DNA<300 copies/mL to >106 copies/mL. We tested goodness of fit using intraclass coefficients (ICC).

RESULTS

Model-projected incidence of HBeAg loss was 5.18% per year over lifetime (ICC, 0.969 (95% CI: 0.728 to 0.990)). For people in HBeAg-negative phases of infection, model-projected HBsAg loss ranged from 0.78% to 3.34% per year depending on HBV DNA level (ICC, 0.889 (95% CI: 0.542 to 0.959)). Model-projected incidence of cirrhosis was 0.29-2.09% per year (ICC, 0.965 (95% CI: 0.942 to 0.979)) and HCC incidence was 0.06-1.65% per year (ICC, 0.977 (95% CI: 0.962 to 0.986)). Over a lifetime simulation of HBV disease, mortality rates were higher for people with older age, higher HBV DNA level and liver-related complications, consistent with observational studies.

CONCLUSIONS

We simulated HBV DNA-stratified clinical outcomes with the novel HEPA-B Model and validated them to observational data. This model can be used to examine strategies of HBV prevention and management.

Prophylaxis for Pneumocystis carinii pneumonia in non-Hodgkin's lymphoma undergoing R-CHOP21 in China: a meta-analysis and cost-effectiveness analysis

OBJECTIVE

Rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone, once every 3 weeks (R-CHOP21) is commonly used in non-Hodgkin's lymphoma (NHL), but accompanied by Pneumocystis carinii pneumonia (PCP) as a fatal treatment complication. This study aims to estimate the specific effectiveness and cost-effectiveness of PCP prophylaxis in NHL undergoing R-CHOP21.

DESIGN

A two-part decision analytical model was developed. Prevention effects were determined by systemic review of PubMed, Embase, Cochrane Library and Web of Science from inception to December 2022. Studies reporting results of PCP prophylaxis were included. Enrolled studies were quality assessed with Newcastle-Ottawa Scale. Costs were derived from the Chinese official websites, and clinical outcomes and utilities were obtained from published literature. Uncertainty was evaluated through deterministic and probabilistic sensitivity analyses (DSA and PSA). Willingness-to-pay (WTP) threshold was set as US$31 315.23/quality-adjusted life year (QALY) (threefold the 2021 per capita Chinese gross domestic product).

SETTING

Chinese healthcare system perspective.

PARTICIPANTS

NHL receiving R-CHOP21.

INTERVENTIONS

PCP prophylaxis versus no prophylaxis.

MAIN OUTCOME MEASURES

Prevention effects were pooled as relative risk (RR) with 95% CI. QALYs and incremental cost-effectiveness ratio (ICER) were calculated.

RESULTS

A total of four retrospective cohort studies with 1796 participants were included. PCP risk was inversely associated with prophylaxis in NHL receiving R-CHOP21 (RR 0.17; 95% CI 0.04 to 0.67; p=0.01). Compared with no prophylaxis, PCP prophylaxis would incur an additional cost of US$527.61, and 0.57 QALYs gained, which yielded an ICER of US$929.25/QALY. DSA indicated that model results were most sensitive to the risk of PCP and preventive effectiveness. In PSA, the probability that prophylaxis was cost-effective at the WTP threshold was 100%.

CONCLUSION

Prophylaxis for PCP in NHL receiving R-CHOP21 is highly effective from retrospective studies, and routine chemoprophylaxis against PCP is overwhelmingly cost-effective from Chinese healthcare system perspective. Large sample size and prospective controlled studies are warranted.

Health Utility Estimates and Their Application to HIV Prevention in the United States: Implications for Cost-Effectiveness Modeling and Future Research Needs

Objectives. Health utility estimates from the current era of HIV treatment, critical for cost-effectiveness analyses (CEA) informing HIV health policy, are limited. We examined peer-reviewed literature to assess the appropriateness of commonly referenced utilities, present previously unreported quality-of-life data from two studies, and discuss future implications for HIV-related CEA. Methods. We searched a database of cost-effectiveness analyses specific to HIV prevention efforts from 1999 to 2016 to identify the most commonly referenced sources for health utilities and to examine practices around using and reporting health utility data. Additionally, we present new utility estimates from the Centers of Disease Control and Prevention’s Medical Monitoring Project (MMP) and the INSIGHT Strategies for Management of Anti-Retroviral Therapy (SMART) trial. We compare data collection time frames, sample characteristics, assessment methods, and key estimates. Results. Data collection for the most frequently cited utility estimates ranged from 1985 to 1997, predating modern HIV treatment. Reporting practices around utility weights are poor and lack details on participant characteristics, which may be important stratifying factors for CEA. More recent utility estimates derived from MMP and SMART were similar across CD4+ count strata and had a narrower range than pre–antiretroviral therapy (ART) utilities. Conclusions. Despite the widespread use of ART, cost-effectiveness analysis of HIV prevention interventions frequently apply pre-ART health utility weights. Use of utility weights reflecting the current state of the US epidemic are needed to best inform HIV research and public policy decisions. Improved practices around the selection, application, and reporting of health utility data used in HIV prevention CEA are needed to improve transparency.

Comparative analyses of published cost effectiveness models highlight critical considerations which are useful to inform development of new models

Background: Comparative analyses of published cost effectiveness models provide useful insights into critical issues to inform the development of new cost effectiveness models in the same disease area.Objective: The purpose of this study was to describe a comparative analysis of cost-effectiveness models and highlight the importance of such work in informing development of new models. This research uses genotypic antiretroviral resistance testing after first line treatment failure for Human Immunodeficiency Virus (HIV) as an example.Method: A literature search was performed, and published cost effectiveness models were selected according to predetermined eligibility criteria. A comprehensive comparative analysis was undertaken for all aspects of the models.Results: Five published models were compared, and several critical issues were identified for consideration when developing a new model. These include the comparator, time horizon and scope of the model. In addition, the composite effect of drug resistance prevalence, antiretroviral therapy efficacy, test performance and the proportion of patients switching to second-line ART potentially have a measurable effect on model results. When considering CD4 count and viral load, dichotomizing patients according to higher cost and lower quality of life (AIDS) versus lower cost and higher quality of life (non-AIDS) status will potentially capture differences between resistance testing and other strategies, which could be confirmed by cross-validation/convergent validation. A quality adjusted life year is an essential outcome which should be explicitly explored in probabilistic sensitivity analysis, where possible.Conclusions: Using an example of GART for HIV, this study demonstrates comparative analysis of previously published cost effectiveness models yields critical information which can be used to inform the structure and specifications of new models.

Economic evaluation studies in the field of HIV/AIDS: bibliometric analysis on research development and scopes (GAPRESEARCH)

Background

The rapid decrease in international funding for HIV/AIDS has been challenging for many nations to effectively mobilize and allocate their limited resources for HIV/AIDS programs. Economic evaluations can help inform decisions and strategic planning. This study aims to examine the trends and patterns in economic evaluation studies in the field of HIV/AIDS and determine their research landscapes.

Methods

Using the Web of Science databases, we synthesized the number of papers and citations on HIV/AIDS and economic evaluation from 1990 to 2017. Collaborations between authors and countries, networks of keywords and research topics were visualized using frequency of co-occurrence and Jaccards’ similarity index. A Latent Dirichlet Allocation (LDA) analysis to categorize papers into different topics/themes.

Results

A total of 372 economic evaluation papers were selected, including 351 cost-effectiveness analyses (CEA), 11 cost-utility analyses (CUA), 12 cost-benefit analyses (CBA). The growth of publications, their citations and usages have increased remarkably over the years. Major research topics in economic evaluation studies consisted of antiretroviral therapy (ART) initiation and treatment; drug use prevention interventions and prevention of mother-to-child transmission interventions. Moreover, lack of contextualized evidence was found in specific settings with high burden HIV epidemics, as well as emerging most-at-risk populations such as trans-genders or migrants.

Conclusion

This study highlights the knowledge and geographical discrepancies in HIV/AIDS economic evaluation literature. Future research directions are also informed for advancing economic evaluation in HIV/AIDS research.

Model-Based Methods to Translate Adolescent Medicine Trials Network for HIV/AIDS Interventions Findings Into Policy Recommendations: Rationale and Protocol for a Modeling Core (ATN 161)

Background

The United States Centers for Disease Control and Prevention estimates that approximately 60,000 US youth are living with HIV. US youth living with HIV (YLWH) have poorer outcomes compared with adults, including lower rates of diagnosis, engagement, retention, and virologic suppression. With Adolescent Medicine Trials Network for HIV/AIDS Interventions (ATN) support, new trials of youth-centered interventions to improve retention in care and medication adherence among YLWH are underway.

Objective

This study aimed to use a computer simulation model, the Cost-Effectiveness of Preventing AIDS Complications (CEPAC)-Adolescent Model, to evaluate selected ongoing and forthcoming ATN interventions to improve viral load suppression among YLWH and to define the benchmarks for uptake, effectiveness, durability of effect, and cost that will make these interventions clinically beneficial and cost-effective.

Methods

This protocol, ATN 161, establishes the ATN Modeling Core. The Modeling Core leverages extensive data—already collected by successfully completed National Institutes of Health–supported studies—to develop novel approaches for modeling critical components of HIV disease and care in YLWH. As new data emerge from ongoing ATN trials during the award period about the effectiveness of novel interventions, the CEPAC-Adolescent simulation model will serve as a flexible tool to project their long-term clinical impact and cost-effectiveness. The Modeling Core will derive model input parameters and create a model structure that reflects key aspects of HIV acquisition, progression, and treatment in YLWH. The ATN Modeling Core Steering Committee, with guidance from ATN leadership and scientific experts, will select and prioritize specific model-based analyses as well as provide feedback on derivation of model input parameters and model assumptions. Project-specific teams will help frame research questions for model-based analyses as well as provide feedback regarding project-specific inputs, results, sensitivity analyses, and policy conclusions.

Results

This project was funded as of September 2017.

Conclusions

The ATN Modeling Core will provide critical information to guide the scale-up of ATN interventions and the translation of ATN data into policy recommendations for YLWH in the United States.

High burden and low awareness of toxoplasmosis in the United States

Toxoplasmosis, a disease with diverse clinical manifestations, caused by infection with the Apicomplexan parasite, Toxoplasma gondii (T. gondii), is a major source of morbidity and mortality in the United States. Although toxoplasmosis prevalence and mortality have declined over the past two decades, the CDC considers this disease a neglected parasitic infection requiring public health action. Here, we overview the literature to bring attention to the prevalence of the disease in the United States, and high economic burden associated with the disease. The conclusions to be drawn are clear: there is low awareness and underestimation of the disease burden amongst healthcare professionals; a high economic burden associated with the disease; relapse rates to treatment represent additional mortality and morbidity and further costs for the healthcare system; and better treatments are necessary to combat this public health threat.

Using Observational Data to Calibrate Simulation Models

BACKGROUND

Individual-level simulation models are valuable tools for comparing the impact of clinical or public health interventions on population health and cost outcomes over time. However, a key challenge is ensuring that outcome estimates correctly reflect real-world impacts. Calibration to targets obtained from randomized trials may be insufficient if trials do not exist for populations, time periods, or interventions of interest. Observational data can provide a wider range of calibration targets but requires methods to adjust for treatment-confounder feedback. We propose the use of the parametric g-formula to estimate calibration targets and present a case-study to demonstrate its application.

METHODS

We used the parametric g-formula applied to data from the HIV-CAUSAL Collaboration to estimate calibration targets for 7-y risks of AIDS and/or death (AIDS/death), as defined by the Center for Disease Control and Prevention under 3 treatment initiation strategies. We compared these targets to projections from the Cost-effectiveness of Preventing AIDS Complications (CEPAC) model for treatment-naïve individuals presenting to care in the following year ranges: 1996 to 1999, 2000 to 2002, or 2003 onwards.

RESULTS

The parametric g-formula estimated a decreased risk of AIDS/death over time and with earlier treatment. The uncalibrated CEPAC model successfully reproduced targets obtained via the g-formula for baseline 1996 to 1999, but over-estimated calibration targets in contemporary populations and failed to reproduce time trends in AIDS/death risk. Calibration to g-formula targets improved CEPAC model fit for contemporary populations.

CONCLUSION

Individual-level simulation models are developed based on best available information about disease processes in one or more populations of interest, but these processes can change over time or between populations. The parametric g-formula provides a method for using observational data to obtain valid calibration targets and enables updating of simulation model inputs when randomized trials are not available.

Cost-utility and budget impact of methylene blue-treated plasma compared to quarantine plasma

BACKGROUND

Methylene blue and visible light treatment and quarantine are two methods used to reduce adverse events, mostly infections, associated with the transfusion of fresh-frozen plasma. The objective of this study was to estimate and compare the budget impact and cost-utility of these two methods from a payer's perspective.

MATERIALS AND METHODS

A budget impact and cost-utility model simulating the risks of hepatitis B virus, hepatitis C virus, cytomegalovirus, a West Nile virus-like infection, allergic reactions and febrile non-haemolytic transfusion reactions achieved using plasma treated with methylene blue and visible light (MBP) and quarantine plasma (QP) was constructed for Spain. QP costs were estimated using data from one blood centre in Spain and published literature. The costs of producing fresh-frozen plasma from whole blood, apheresis plasma, and multicomponent apheresis, and separately for passive and active methods of donor recall for QP were included. Costs and outcomes over a 5-year and lifetime time horizon were estimated.

RESULTS

Compared to passive QP, MBP led to a net increase of € 850,352, and compared to active QP, MBP led to a net saving of € 5,890,425 over a 5-year period. Compared to passive QP, MBP increased the cost of fresh-frozen plasma per patient by € 7.21 and had an incremental cost-utility ratio of € 705,126 per quality-adjusted life-year. Compared to active QP, MBP reduced cost by € 50.46 per patient and was more effective.

DISCUSSION

Plasma collection method and quarantine approach had the strongest influence on the budget impact and cost-utility of MBP. If QP relies on plasma from whole blood collection and passive quarantine, it is less costly than MBP. However, MPB was estimated to be more effective than QP in all analyses.

Autoimmunity and dysmetabolism of human acquired immunodeficiency syndrome

Acquired immunodeficiency syndrome (AIDS) remains ill-defined by lists of symptoms, infections, tumors, and disorders in metabolism and immunity. Low CD4 cell count, severe loss of body weight, pneumocystis pneumonia, and Kaposi's sarcoma are the major disease indicators. Lines of evidence indicate that patients living with AIDS have both immunodeficiency and autoimmunity. Immunodeficiency is attributed to deficits in the skin- and mucosa-defined innate immunity, CD4 T cells and regulatory T cells, presumably relating human immunodeficiency virus (HIV) infection. The autoimmunity in AIDS is evident by: (1) overproduction of autoantibodies, (2) impaired response of CD4 cells and CD8 cells, (3) failure of clinical trials of HIV vaccines, and (4) therapeutic benefits of immunosuppression following solid organ transplantation and bone marrow transplantation in patients at risk of AIDS. Autoantibodies are generated in response to antigens such as debris and molecules de novo released from dead cells, infectious agents, and catabolic events. Disturbances in metabolic homeostasis occur at the interface of immunodeficiency and autoimmunity in the development of AIDS. Optimal treatments favor therapeutics targeting on the regulation of metabolism to restore immune homeostasis.

Betting on the fastest horse: Using computer simulation to design a combination HIV intervention for future projects in Maharashtra, India

Objective

To inform the design of a combination intervention strategy targeting HIV-infected unhealthy alcohol users in Maharashtra, India, that could be tested in future randomized control trials.

Methods

Using probabilistic compartmental simulation modeling we compared intervention strategies targeting HIV-infected unhealthy alcohol users on antiretroviral therapy (ART) in Maharashtra, India. We tested interventions targeting four behaviors (unhealthy alcohol consumption, risky sexual behavior, depression and antiretroviral adherence), in three formats (individual, group based, community) and two durations (shorter versus longer). A total of 5,386 possible intervention combinations were tested across the population for a 20-year time horizon and intervention bundles were narrowed down based on incremental cost-effectiveness analysis using a two-step probabilistic uncertainty analysis approach.

Results

Taking into account uncertainty in transmission variables and intervention cost and effectiveness values, we were able to reduce the number of possible intervention combinations to be used in a randomized control trial from over 5,000 to less than 5. The most robust intervention bundle identified was a combination of three interventions: long individual alcohol counseling; weekly Short Message Service (SMS) adherence counseling; and brief sex risk group counseling.

Conclusions

In addition to guiding policy design, simulation modeling of HIV transmission can be used as a preparatory step to trial design, offering a method for intervention pre-selection at a reduced cost.

Economic evaluation of mobile phone text message interventions to improve adherence to HIV therapy in Kenya

BACKGROUND

A surge in mobile phone availability has fueled low cost short messaging service (SMS) adherence interventions. Multiple systematic reviews have concluded that some SMS-based interventions are effective at improving antiretroviral therapy (ART) adherence, and they are hypothesized to improve retention in care. The objective of this study was to evaluate the cost-effectiveness of SMS-based adherence interventions and explore the added value of retention benefits.

METHODS

We evaluated the cost-effectiveness of weekly SMS interventions compared to standard care among HIV+ individuals initiating ART for the first time in Kenya. We used an individual level micro-simulation model populated with data from two SMS-intervention trials, an East-African HIV+ cohort and published literature. We estimated average quality adjusted life years (QALY) and lifetime HIV-related costs from a healthcare perspective. We explored a wide range of scenarios and assumptions in one-way and multivariate sensitivity analyses.

RESULTS

We found that SMS-based adherence interventions were cost-effective by WHO standards, with an incremental cost-effectiveness ratio (ICER) of $1,037/QALY. In the secondary analysis, potential retention benefits improved the cost-effectiveness of SMS intervention (ICER = $864/QALY). In multivariate sensitivity analyses, the interventions remained cost-effective in most analyses, but the ICER was highly sensitive to intervention costs, effectiveness and average cohort CD4 count at ART initiation. SMS interventions remained cost-effective in a test and treat scenario where individuals were assumed to initiate ART upon HIV detection.

CONCLUSIONS

Effective SMS interventions would likely increase the efficiency of ART programs by improving HIV treatment outcomes at relatively low costs, and they could facilitate achievement of the UNAIDS goal of 90% viral suppression among those on ART by 2020.

A Bayesian Approach to Net Health Benefits: An Illustration and Application to Modeling HIV Prevention

Purpose. To conduct a cost-effectiveness analysis of HIV prevention when costs and effects cannot be measured directly. To quantify the total estimation of uncertainty due to sampling variability as well as inexact knowledge of HIV transmission parameters. Methods. The authors focus on estimating the incremental net health benefit (INHB) in a randomized trial of HIV prevention with intervention and control conditions. Using a Bernoulli model of HIV transmission, changes in the participants’ risk behaviors are converted into the number of HIV infections averted. A sampling model is used to account for variation in the behavior measurements. Bayes’s theorem and Monte Carlo methods are used to attain the stated objectives. Results. The authors obtained a positive mean INHB of 0.0008, indicating that advocacy training is just slightly favored over the control condition for men, assuming a $50,000 per quality-adjusted life year (QALY) threshold. To be confident of a positive INHB, the decision maker would need to spend more than $100,000 per QALY.

Cost-Effectiveness of Interventions to Reduce Vertical HIV Transmission from Pregnant Women Who Have Not Received Prenatal Care

To evaluate the cost-effectiveness of rapid HIV testing followed by treatmentwith zidovudine, nevirapine, or combination therapy for women presenting in the United States in active labor without prenatal care, the authors developed a decision analytic model from a societal perspective comparing 2 basic strategies: 1) not testing for HIV and 2) offering rapid HIV testing and treatment to women testing positive. HIV transmission rates, test characteristics, and costs were derived from the literature and local sources. Outcomes included number of infected infants, costs, and incremental cost-effectiveness in dollars per quality-adjusted life year saved. The authors found that offering rapid HIV testing and administering zidovudine treatment to women testing positive would prevent 27 cases of HIV each year and save $3,000,000/year compared with no intervention. If more expensive treatments were used (e.g., zidovudine rather than nevirapine, or combination therapy rather than monotherapy), the relative risk reduction in HIV transmission for the more expensive strategies would need to be only slightly better to make the more expensive strategies relatively costeffective in comparison with the less expensive strategies. In an analysis including empiric nevirapine prophylaxis, the authors found that empiric therapy would prevent 32 HIV cases and save $2.1million per year compared with no intervention. In conclusion, rapid HIV testing and treatment for women presenting in labor without prior prenatal care would prevent HIV infections and save costs. At sites where rapid HIV testing is not possible, empiric treatment would also prevent HIV infection and saves costs and is thus preferred to a strategy of neither testing nor treating. Effectiveness in reducing transmission drives the cost-effectiveness ratio much more so than drug cost and should be the basis on which a particular prophylactic regimen is selected.

Utilities Derived from Visual Analog Scale Scores in Patients with HIV/AIDS

Background. Visual analog scale (VAS) scores are used as global quality-of-life indicators and, unlike true utilities (which assess the desirability of health states v. an external metric), are often collected in HIV-related clinical trials. The purpose of this study was to derive and evaluate transformations relating aggregate VAS scores to utilities for current health in patients with HIV/AIDS. Methods. HIV-specific transformations were developed using linear and nonlinear regression to attain models that best fit mean VAS and standard gamble (SG) utility values directly derived from 299 patients with HIV/AIDS participating in a multicenter study of health values. The authors evaluated the transformations using VAS and SG utility values derived directly from patients in other HIV/AIDS studies. Derived transformations were also compared with published transformations. Results. A simple linear transformation was derived (u = 0.44v + 0.49), as was the exponent for a curvilinear model (u = 1-[1- v ]1.6 ), where u = the sample mean utility and v the sample mean VAS score. The curvilinear transformation predicted values within 0.10 of the actual SG utility in 5 of 8 estimates and within 0.05 in 3 of 8 estimates (absolute error ranged from -0.01 to +0.21). The linear transformation performed some-what better, predicting within 0.10 of the actual SG value in 6 of 8 cases and within 0.05 in 5 of 8 estimates (absolute error ranged from -0.05 to +0.13). An alternative linear model (u =v + 0.018) derived from the literature performed similarly to our linear model (7 of 8 predictions within 0.10, 1 of 8 estimates within 0.05, and absolute error ranging from -0.15 to +0.10), whereas an alternative published curvilinear model (u = 1 - [1 - v ]2.3 ) performed the least well (2 of 8 estimates within 0.10 of the actual values and no estimates within 0.05). Conclusions. Predicted utilities are a reasonable alter-native for use in HIV/AIDS decision analyses and costeffectiveness analyses. Linear transformations performed better than curvilinear transformations in this context and can be used to convert aggregate VAS scores to aggregate SG values in large HIV/AIDS studies that collect VAS data but not utilities.

Cost-effectiveness of CYP2B6 genotyping to optimize efavirenz dosing in HIV clinical practice

AIMS

To assess the cost-effectiveness of CYP2B6 genotyping to guide efavirenz dosing for initial HIV therapy in the USA.

METHODS

We used the Cost-Effectiveness of Preventing AIDS Complications (CEPAC) microsimulation model to project quality-adjusted life expectancy and lifetime costs (2014 US dollars) for efavirenz-based HIV therapy with or without CYP2B6 genotyping. We assumed that with genotyping 60% of patients would be eligible to receive lower doses.

RESULTS

Current care without CYP2B6 genotyping has an incremental cost-effectiveness ratio >$100,000/QALY compared with genotype-guided dosing, even if lower dosing reduces efficacy. When we assumed generic efavirenz availability, conclusions were similar unless lower dosing reduces efficacy by 6% or more.

CONCLUSION

CYP2B6 genotyping can inform efavirenz dosing and decrease HIV therapy cost.

Cost-effectiveness analysis along the continuum of HIV care: how can we optimize the effect of HIV treatment as prevention programs?

The cascade of HIV care has been proposed as a useful tool to monitor health system performance across the key stages of HIV care delivery to reduce morbidity, mortality, and HIV transmission, the focal points of HIV Treatment as Prevention campaigns. Interventions to improve the cascade at its various stages may vary substantially in their ability to deliver health value per amount expended. In order to meet global antiretroviral treatment access targets, there is an urgent need to maximize the value of health spending by prioritizing cost-effective interventions. We executed a literature review on economic evaluations of interventions to improve specific stages of the cascade of HIV care. In total, 33 articles met the criteria for inclusion in the review, 22 (67 %) of which were published within the last 5 years. Nonetheless, substantial gaps in our knowledge remain, particularly for interventions to improve linkage and retention in HIV care in developed and developing-world settings and generalized and concentrated epidemics. We make the case here that the attention of scientists and policymakers needs to turn to the development, implementation, and rigorous evaluation of interventions to improve the various stages of the cascade of HIV care.

Cost-effectiveness of population-level expansion of highly active antiretroviral treatment for HIV in British Columbia, Canada: a modelling study

BACKGROUND

Widespread HIV screening and access to highly active antiretroviral treatment (ART) were cost effective in mathematical models, but population-level implementation has led to questions about cost, value, and feasibility. In 1996, British Columbia, Canada, introduced universal coverage of drug and other health-care costs for people with HIV/AIDS and and began extensive scale-up in access to ART. We aimed to assess the cost-effectiveness of ART scale-up in British Columbia compared with hypothetical scenarios of constrained treatment access.

METHODS

Using comprehensive linked population-level data, we populated a dynamic, compartmental transmission model to simulate the HIV/AIDS epidemic in British Columbia from 1997 to 2010. We estimated HIV incidence, prevalence, mortality, costs (in 2010 CAN$), and quality-adjusted life-years (QALYs) for the study period, which was 1997-2010. We calculated incremental cost-effectiveness ratios from societal and third-party-payer perspectives to compare actual practice (true numbers of individuals accessing ART) to scenarios of constrained expansion (75% and 50% probability of accessing ART). We also investigated structural and parameter uncertainty.

FINDINGS

Actual practice resulted in 263 averted incident cases compared with 75% of observed access and 676 averted cases compared with 50% of observed access to ART. From a third-party-payer perspective, actual practice resulted in incremental cost-effectiveness ratios of $23 679 per QALY versus 75% access and $24 250 per QALY versus 50% access. From a societal perspective, actual practice was cost saving within the study period. When the model was extended to 2035, current observed access resulted in cumulative savings of $25·1 million compared with the 75% access scenario and $65·5 million compared with the 50% access scenario.

INTERPRETATION

ART scale-up in British Columbia has decreased HIV-related morbidity, mortality, and transmission. Resulting incremental cost-effectiveness ratios for actual practice, derived within a limited timeframe, were within established cost-effectiveness thresholds and were cost saving from a societal perspective.

FUNDING

BC Ministry of Health, National Institute of Drug Abuse at the US National Institutes of Health.

Cost-effectiveness of genotype testing for primary resistance in Brazil

Supplemental Digital Content is Available in the Text.

Objective:

HIV genotype-resistance testing can help identify more effective antiretroviral treatment (ART) regimens for patients, substantially increasing the likelihood of viral suppression and immune recovery. We sought to evaluate the cost-effectiveness of genotype-resistance testing before first-line ART initiation in Brazil.

Design:

We used a previously published microsimulation model of HIV disease (CEPAC-International) and data from Brazil to compare the clinical impact, costs, and cost-effectiveness of initial genotype testing (Genotype) with no initial genotype testing (No genotype).

Methods:

Model parameters were derived from the HIV Clinical Cohort at the Evandro Chagas Clinical Research Institute and from published data, using Brazilian sources whenever possible. Baseline patient characteristics included 69% male, mean age of 36 years (SD, 10 years), mean CD4 count of 347 per microliter (SD, 300/µL) at ART initiation, annual ART costs from 2012 US $1400 to US $13,400, genotype test cost of US $230, and primary resistance prevalence of 4.4%. Life expectancy and costs were discounted 3% per year. Genotype was defined as “cost-effective” compared with No Genotype if its incremental cost-effectiveness ratio was less than 3 times the 2012 Brazilian per capita GDP of US $12,300.

Results:

Compared with No genotype, Genotype increased life expectancy from 18.45 to 18.47 years and reduced lifetime cost from US $45,000 to $44,770; thus, in the base case, Genotype was cost saving. Genotype was cost-effective at primary resistance prevalence as low as 1.4% and remained cost-effective when subsequent-line ART costs decreased to 30% of baseline value. Cost-inefficient results were observed only when simultaneously holding multiple parameters to extremes of their plausible ranges.

Conclusions:

Genotype-resistance testing in ART-naive individuals in Brazil will improve survival and decrease costs and should be incorporated into HIV treatment guidelines in Brazil.

Cost-Effectiveness of Enfuvirtide for Treatment-Experienced Patients with HIV in Italy

BACKGROUND

Enfuvirtide (ENF) plus an optimized background (OB) antiretroviral regimen delays virological failure (VF), reduces HIV-1 viral load, and increases CD4 count compared with OB only in pretreated patients.

PURPOSE

To forecast long-term outcomes, costs, and cost-effectiveness of ENF+OB vs. OB in the Italian health care system.

METHOD

A Markov model was developed and clinical trial results on viral suppression and CD4 count were linked with data from HAART-era studies of the risk of AIDS-defining events (ADEs) and death. Resource data were obtained from Italian sources on direct medical costs. Cost-effectiveness was computed as the incremental cost per quality-adjusted life year (QALY) saved.

RESULTS

Patients receiving ENF+OB were projected to experience a mean time to virological failure of 1.0 years vs. 0.5 years for OB and mean time to immunological failure of 3.1 years vs. 1.3 years for OB. Life expectancy and QALYs were greater for ENF+OB than OB by 1.8 and 1.5 years, respectively. Total lifetime medical cost was euro 126,487 for ENF+OB and euro 84,416 for OB, a difference of euro 42,071 due to the cost of ENF itself (euro 18,400) and the medical costs associated with additional life expectancy (euro 23,671). The incremental cost-effectiveness of ENF+OB was euro 23,721 per life year (euro 28,669 per QALY).

CONCLUSION

ENF+OB is predicted to increase life expectancy at a cost per life year that is comparable to many well-accepted therapies in Europe.

Cost-effectiveness of community vegetable gardens for people living with HIV in Zimbabwe

BACKGROUND

There is little evidence to date of the potential impact of vegetable gardens on people living with HIV (PLHIV), who often suffer from social and economic losses due to the disease. From 2008 through 2011, Action Contre la Faim France (ACF) implemented a project in Chipinge District, eastern Zimbabwe, providing low-input vegetable gardens (LIGs) to households of PLHIV. Program partners included Médecins du Monde, which provided medical support, and Zimbabwe's Agricultural Extension Service, which supported vegetable cultivation. A survey conducted at the end of the program found LIG participants to have higher Food Consumption Scores (FCS) and Household Dietary Diversity Scores (HDDS) relative to comparator households of PLHIV receiving other support programs. This study assessed the incremental cost-effectiveness of LIGs to improve FCS and HDDS of PLHIV compared to other support programs.

METHODS

This analysis used an activity-based cost model, and combined ACF accounting data with estimates of partner and beneficiary costs derived using an ingredients approach to build an estimate of total program resource use. A societal perspective was adopted to encompass costs to beneficiary households, including their opportunity costs and an estimate of their income earned from vegetable sales. Qualitative methods were used to assess program benefits to beneficiary households. Effectiveness data was taken from a previously-conducted survey.

RESULTS

Providing LIGs to PLHIV cost an additional 8,299 EUR per household with adequate FCS and 12,456 EUR per household with HDDS in the upper tertile, relative to comparator households of PLHIV receiving other support programs. Beneficiaries cited multiple tangible and intangible benefits from LIGs, and over 80% of gardens observed were still functioning more than one year after the program had finished.

CONCLUSIONS

Cost outcomes were 20-30 times Zimbabwe's per capita GDP, and unlikely to be affordable within government services. This analysis concludes that LIGs are not cost-effective or affordable relative to other interventions for improving health and nutrition status of PLHIV. Nonetheless, given the myriad benefits acquired by participant households, such programs hold important potential to improve quality of life and reduce stigma against PLHIV.

Optimal control of a two-strain tuberculosis-HIV/AIDS co-infection model

Tuberculosis is a bacterial disease caused by Mycobacterium tuberculosis (TB). The risk for TB infection greatly increases with HIV infection; TB disease occurs in 7-10% of patients with HIV infection each year, increasing the potential for transmission of drug-resistant Mycobacterium tuberculosis strains. In this paper a deterministic model is presented and studied for the transmission of TB-HIV/AIDS co-infection. Optimal control theory is then applied to investigate optimal strategies for controlling the spread of the disease using treatment of infected individuals with TB as the system control variables. Various combination strategies were examined so as to investigate the impact of the controls on the spread of the disease. And incremental cost-effectiveness ratio (ICER) was used to investigate the cost effectiveness of all the control strategies. Our results show that the implementation of the combination strategy involving the prevention of treatment failure in drug-sensitive TB infectious individuals and the treatment of individuals with drug-resistant TB is the most cost-effective control strategy. Similar results were obtained with different objective functionals involving the minimization of the number of individuals with drug-sensitive TB-only and drug-resistant TB-only with the efforts involved in applying the control.

A cost-effectiveness analysis of HIV preexposure prophylaxis for men who have sex with men in Australia

BACKGROUND

Antiretroviral therapy (ART) used as preexposure prophylaxis (PrEP) by human immunodeficiency virus (HIV)-seronegative individuals reduces the risk of acquiring HIV. However, the population-level impact and cost-effectiveness of using PrEP as a public health intervention remains debated.

METHODS

We used a stochastic agent-based model of HIV transmission and progression to simulate the clinical and cost outcomes of different strategies of providing PrEP to men who have sex with men (MSM) in New South Wales (NSW), Australia. Model outcomes were reported as incremental cost-effectiveness ratios (ICERs) in 2013 Australian dollars per quality-adjusted life-year gained (QALYG).

RESULTS

The use of PrEP in 10%-30% of the entire NSW MSM population was projected to cost an additional $316-$952 million over the course of 10 years, and cost >$400 000 per QALYG compared with the status quo. Targeting MSM with sexual partners ranging between >10 to >50 partners within 6 months cost an additional $31-$331 million dollars, and cost >$110 000 per QALYG compared with the status quo. We found that preexposure prophylaxis is most cost-effective when targeted for HIV-negative MSM in a discordant regular partnership. The ICERs ranged between $8399 and $11 575, for coverage ranging between 15% and 30%, respectively.

CONCLUSIONS

Targeting HIV-negative MSM in a discordant regular partnership is a cost-effective intervention. However, this highly targeted strategy would not have large population-level impact. Other scenarios are unlikely to be cost-effective.

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.

Cost effectiveness of cryptococcal antigen screening as a strategy to prevent HIV-associated cryptococcal meningitis in South Africa

Objectives

Cryptococcal meningitis (CM)-related mortality may be prevented by screening patients for sub-clinical cryptococcal antigenaemia (CRAG) at antiretroviral-therapy (ART) initiation and pre-emptively treating those testing positive. Prior to programmatic implementation in South Africa we performed a cost-effectiveness analysis of alternative preventive strategies for CM.

Design

Cost-effectiveness analysis.

Methods

Using South African data we modelled the cost-effectiveness of four strategies for patients with CD4 cell-counts <100 cells/µl starting ART 1) no screening or prophylaxis (standard of care), 2) universal primary fluconazole prophylaxis, 3) CRAG screening with fluconazole treatment if antigen-positive, 4) CRAG screening with lumbar puncture if antigen-positive and either amphotericin-B for those with CNS disease or fluconazole for those without. Analysis was limited to the first year of ART.

Results

The least costly strategy was CRAG screening followed by high-dose fluconazole treatment of all CRAG-positive individuals. This strategy dominated the standard of care at CRAG prevalence ≥0.6%. Although CRAG screening followed by lumbar puncture in all antigen-positive individuals was the most effective strategy clinically, the incremental benefit of LPs and amphotericin therapy for those with CNS disease was small and additional costs were large (US$158 versus US$51per person year; incremental cost effectiveness ratio(ICER) US$889,267 per life year gained). Both CRAG screening strategies are less costly and more clinically effective than current practice. Primary prophylaxis is more effective than current practice, but relatively cost-ineffective (ICER US$20,495).

Conclusions

CRAG screening would be a cost-effective strategy to prevent CM-related mortality among patients initiating ART in South Africa. These findings provide further justification for programmatic implementation of CRAG screening.

Optimal isolation control strategies and cost-effectiveness analysis of a two-strain avian influenza model

The most important and effective measures against disease outbreaks in the absence of valid medicines or vaccine are quarantine and isolation strategies. In this paper optimal control theory is applied to a system of ordinary differential equation describing a two-strain avian influenza transmission via the Pontryagin's Maximum Principle. To this end, a pair of control variables representing the isolation strategies for individuals with avian and mutant strains were incorporated into the transmission model. The infection averted ratio (IAR) and the incremental cost-effectiveness ratio (ICER) were calculated to investigate the cost-effectiveness of all possible combinations of the control strategies. The simulation results show that the implementation of the combination strategy during the epidemic is the most cost-effective strategy for avian influenza transmission. This is followed by the control strategy involving isolation of individuals with the mutant strain. Also observed was the fact that low mutating and more virulent virus results in an increased control effort of isolating individuals with the avian strain; and high mutating with more virulent virus results in increased efforts in isolating individuals with the mutant strain.

State-space size considerations for disease-progression models

Markov models of disease progression are widely used to model transitions in patients' health state over time. Usually, patients' health status may be classified according to a set of ordered health states. Modelers lump together similar health states into a finite and usually small, number of health states that form the basis of a Markov chain disease-progression model. This increases the number of observations used to estimate each parameter in the transition probability matrix. However, lumping together observably distinct health states also obscures distinctions among them and may reduce the predictive power of the model. Moreover, as we demonstrate, precision in estimating the model parameters does not necessarily improve as the number of states in the model declines. This paper explores the tradeoff between lumping error introduced by grouping distinct health states and sampling error that arises when there are insufficient patient data to precisely estimate the transition probability matrix.

Cost-effectiveness of surveillance strategies after treatment for high-grade anal dysplasia in high-risk patients

BACKGROUND

Anal cancer is one of the most common cancers affecting human immunodeficiency virus (HIV)-infected male patients. Currently, there is no consensus on posttreatment surveillance of HIV-infected men who have sex with men (MSM) who have been treated for high-grade intraepithelial neoplasia (HGAIN), the likely precursor to anal cancer.

OBJECTIVE

The aim of this study was to assess the cost-effectiveness of a range of strategies for anal cancer surveillance in HIV-infected MSM previously treated for HGAIN.

METHODS

We developed a Markov model to project quality-adjusted life expectancy, lifetime costs, and the incremental cost-effectiveness ratios of 5 strategies using high-resolution anoscopy (HRA) and/or anal cytology testing after treatment.

RESULTS

Performing HRA alone at 6- and 12-month visits was associated with a cost-effectiveness ratio of $4446 per quality-adjusted life year gained. In comparison, combined HRA and anal cytology at both visits provided greater health benefit at a cost of $17,373 per quality-adjusted life year gained. Our results were robust over a number of scenarios and assumptions including patients' level of immunosuppression. Results were most sensitive to test characteristics and cost, as well as progression rates of normal to HGAIN and HGAIN to cancer.

CONCLUSIONS

Our results suggest that combined HRA and anal cytology at 6 and 12 months may be a cost-effective surveillance strategy after treatment of HGAIN in HIV-infected MSM.

Cost-utility analysis of lopinavir/ritonavir versus atazanavir + ritonavir administered as first-line therapy for the treatment of HIV infection in Italy: from randomised trial to real world

Objective

To estimate the lifetime cost utility of two antiretroviral regimens (once-daily atazanavir plus ritonavir [ATV+r] versus twice-daily lopinavir/ritonavir [LPV/r]) in Italian human immunodeficiency virus (HIV)-infected patients naïve to treatment.

Design

With this observational retrospective study we collected the clinical data of a cohort of HIV-infected patients receiving first-line treatment with LPV/r or ATV+r.

Methodology

A Markov microsimulation model including direct costs and health outcomes of first- and second-line highly active retroviral therapy was developed from a third-party (Italian National Healthcare Service) payer’s perspective. Health and monetary outcomes associated with the long-term use of ATV+r and LPV/r regimens were evaluated on the basis of eight health states, incidence of diarrhoea and hyperbilirubinemia, AIDS events, opportunistic infections, coronary heart disease events and, for the first time in an economic evaluation, chronic kidney disease (CKD) events. In order to account for possible deviations between real-life data and randomised controlled trial results, a second control arm (ATV+r 2) was created with differential transition probabilities taken from the literature.

Results

The average survival was 24.061 years for patients receiving LPV/r, 24.081 and 24.084 for those receiving ATV+r 1 and 2 respectively. The mean quality-adjusted life-years (QALYs) were higher for the patients receiving LPV/r than those receiving ATV+r (13.322 vs. 13.060 and 13.261 for ATV+r 1 and 2). The cost-utility values were 15,310.56 for LPV/r, 15,902.99 and 15,524.85 for ATV+r 1 and 2.

Conclusions

Using real-life data, the model produced significantly different results compared with other studies. With the innovative addition of an evaluation of CKD events, the model showed a cost-utility value advantage for twice-daily LPV/r over once-daily ATV+r, thus providing evidence for its continued use in the treatment of HIV.

The potential cost and benefits of raltegravir in simplified second-line therapy among HIV infected patients in Nigeria and South Africa

BACKGROUND

There is an urgent need to improve the evidence base for provision of second-line antiretroviral therapy (ART) following first-line virological failure. This is particularly the case in Sub-Saharan Africa where 70% of all people living with HIV/AIDS (PHA) reside. The aim of this study was to simulate the potential risks and benefits of treatment simplification in second-line therapy compared to the current standard of care (SOC) in a lower-middle income and an upper-middle income country in Sub-Saharan Africa.

METHODS

We developed a microsimulation model to compare outcomes associated with reducing treatment discontinuations between current SOC for second-line therapy in South Africa and Nigeria and an alternative regimen: ritonavir-boosted lopinavir (LPV/r) combined with raltegravir (RAL). We used published studies and collaborating sites to estimate efficacy, adverse effect and cost. Model outcomes were reported as incremental cost effectiveness ratios (ICERs) in 2011 USD per quality adjusted life year ($/QALY) gained.

RESULTS

Reducing treatment discontinuations with LPV/r+RAL resulted in an additional 0.4 discounted QALYs and increased the undiscounted life expectancy by 0.8 years per person compared to the current SOC. The average incremental cost was $6,525 per treated patient in Nigeria and $4,409 per treated patient in South Africa. The cost-effectiveness ratios were $16,302/QALY gained and $11,085/QALY gained for Nigeria and South Africa, respectively. Our results were sensitive to the probability of ART discontinuation and the unit cost for RAL.

CONCLUSIONS

The combination of raltegravir and ritonavir-boosted lopinavir was projected to be cost-effective in South Africa. However, at its current price, it is unlikely to be cost-effective in Nigeria.

Conceptualizing a model: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force-2

The appropriate development of a model begins with understanding the problem that is being represented. The aim of this article is to provide a series of consensus-based best practices regarding the process of model conceptualization. For the purpose of this series of papers, the authors consider the development of models whose purpose is to inform medical decisions and health-related resource allocation questions. They specifically divide the conceptualization process into two distinct components: the conceptualization of the problem, which converts knowledge of the health care process or decision into a representation of the problem, followed by the conceptualization of the model itself, which matches the attributes and characteristics of a particular modeling type to the needs of the problem being represented. Recommendations are made regarding the structure of the modeling team, agreement on the statement of the problem, the structure, perspective and target population of the model, and the interventions and outcomes represented. Best practices relating to the specific characteristics of model structure, and which characteristics of the problem might be most easily represented in a specific modeling method, are presented. Each section contains a number of recommendations that were iterated among the authors, as well as the wider modeling taskforce, jointly set up by the International Society for Pharmacoeconomics and Outcomes Research and the Society for Medical Decision Making.

Cost-effectiveness analysis of UGT1A1 genetic testing to inform antiretroviral prescribing in HIV disease

BACKGROUND

Homozygosity for UGT1A1*28/*28 has been reported to be associated with atazanavir-associated hyperbilirubinaemia and premature atazanavir discontinuation. We assessed the potential cost-effectiveness of UGT1A1 testing to inform the choice of an initial protease-inhibitor-containing regimen in antiretroviral therapy (ART)-naive individuals.

METHODS

We used the Cost-Effectiveness of Preventing AIDS Complications computer simulation model to project quality-adjusted life years (QALYs) and lifetime costs (2009 USD) for atazanavir-based ART with or without UGT1A1 testing, using darunavir rather than atazanavir when indicated. We assumed the UGT1A1-associated atazanavir discontinuation rate reported in the Swiss HIV Cohort Study (a *28/*28 frequency of 14.9%), equal efficacy and cost of atazanavir and darunavir and a genetic assay cost of $107. These parameters, as well as the effect of hyperbilirubinaemia on quality of life and loss to follow up, were varied in sensitivity analyses. Costs and QALYs were discounted at 3% annually.

RESULTS

Initiating atazanavir-based ART at CD4(+) T-cell counts <500 cells/μl without UGT1A1 testing had an average discounted life expectancy of 16.02 QALYs and $475,800 discounted lifetime cost. Testing for UGT1A1 increased QALYs by 0.49 per 10,000 patients tested and was not cost-effective (>$100,000/QALY). Testing for UGT1A1 was cost-effective (<$100,000/QALY) if assay cost decreased to $10, or if avoiding hyperbilirubinaemia by UGT1A1 testing reduced loss to follow-up by 5%. If atazanavir and darunavir differed in cost or efficacy, testing for UGT1A1 was not cost-effective under any scenario.

CONCLUSIONS

Testing for UGT1A1 may be cost-effective if assay cost is low and if testing improves retention in care, but only if the comparator ART regimens have the same drug cost and efficacy.

The determinants of HIV treatment costs in resource limited settings

BACKGROUND

Governments and international donors have partnered to provide free HIV treatment to over 6 million individuals in low and middle-income countries. Understanding the determinants of HIV treatment costs will help improve efficiency and provide greater certainty about future resource needs.

METHODS AND FINDINGS

We collected data on HIV treatment costs from 54 clinical sites in Botswana, Ethiopia, Mozambique, Nigeria, Uganda, and Vietnam. Sites provided free HIV treatment funded by the U.S. President's Emergency Plan for AIDS Relief (PEPFAR), national governments, and other partners. Service delivery costs were categorized into successive six-month periods from the date when each site began HIV treatment scale-up. A generalized linear mixed model was used to investigate relationships between site characteristics and per-patient costs, excluding ARV expenses. With predictors at their mean values, average annual per-patient costs were $177 (95% CI: 127-235) for pre-ART patients, $353 (255-468) for adult patients in the first 6 months of ART, and $222 (161-296) for adult patients on ART for >6 months (excludes ARV costs). Patient volume (no. patients receiving treatment) and site maturity (months since clinic began providing treatment services) were both strong independent predictors of per-patient costs. Controlling for other factors, costs declined by 43% (18-63) as patient volume increased from 500 to 5,000 patients, and by 28% (6-47) from 5,000 to 10,000 patients. For site maturity, costs dropped 41% (28-52) between months 0-12 and 25% (15-35) between months 12-24. Price levels (proxied by per-capita GDP) were also influential, with costs increasing by 22% (4-41) for each doubling in per-capita GDP. Additionally, the frequency of clinical follow-up, frequency of laboratory monitoring, and clinician-patient ratio were significant independent predictors of per-patient costs.

CONCLUSIONS

Substantial reductions in per-patient service delivery costs occur as sites mature and patient cohorts increase in size. Other predictors suggest possible strategies to reduce per-patient costs.

Modeling asthma exacerbations through lung function in children

BACKGROUND

Formal economic evaluation using a model-based approach is playing an increasingly important role in health care decision making.

OBJECTIVE

To develop a model by using an objective measure of lung function-- prebronchodilator FEV(1) as a percent of predicted (FEV(1)% predicted)--as the primary independent factor to predict the frequency of adverse events related to the exacerbation of asthma on a population level.

METHODS

We developed a Markov simulation model of childhood asthma by using data from the Childhood Asthma Management Program. The primary outcomes were the result of asthma exacerbations defined as hospitalizations, emergency department (ED) visits, and the need for oral corticosteroid therapy. Predicted monthly frequencies for each acute event were based on negative binomial regression equations estimated from the placebo arm of the Childhood Asthma Management Program with covariates of age, prebronchodilator FEV(1)% predicted, time in study, prior hospitalizations, and prior nocturnal awakenings.

RESULTS

Simulated versus observed mean number of acute events were similar within the placebo and treatment groups. While the trial demonstrated treatment effects of 48% reduction in hospitalizations, 46% reduction in ED visits, and 44% reduction in the need for oral corticosteroid therapy at 48 months, the model simulated similar reductions of 49% in hospitalizations, 41% in ED visits, and 46% in the need for oral corticosteroid therapy.

CONCLUSIONS

Our findings suggest that longitudinal intervention effects may be modeled through FEV(1)% predicted to estimate hospitalizations, ED visits, and need for oral corticosteroid therapy in childhood asthma for planning and evaluation purposes.

State-Transition Modeling

State-transition modeling (STM) is an intuitive, flexible, and transparent approach of computer-based decision-analytic modeling, including both Markov model cohort simulation as well as individual-based (first-order Monte Carlo) microsimulation. Conceptualizing a decision problem in terms of a set of (health) states and transitions among these states, STM is one of the most widespread modeling techniques in clinical decision analysis, health technology assessment, and health-economic evaluation. STMs have been used in many different populations and diseases, and their applications range from personalized health care strategies to public health programs. Most frequently, state-transition models are used in the evaluation of risk factor interventions, screening, diagnostic procedures, treatment strategies, and disease management programs.

State-transition modeling: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force--3

State-transition modeling is an intuitive, flexible, and transparent approach of computer-based decision-analytic modeling including both Markov model cohort simulation and individual-based (first-order Monte Carlo) microsimulation. Conceptualizing a decision problem in terms of a set of (health) states and transitions among these states, state-transition modeling is one of the most widespread modeling techniques in clinical decision analysis, health technology assessment, and health-economic evaluation. State-transition models have been used in many different populations and diseases, and their applications range from personalized health care strategies to public health programs. Most frequently, state-transition models are used in the evaluation of risk factor interventions, screening, diagnostic procedures, treatment strategies, and disease management programs. The goal of this article was to provide consensus-based guidelines for the application of state-transition models in the context of health care. We structured the best practice recommendations in the following sections: choice of model type (cohort vs. individual-level model), model structure, model parameters, analysis, reporting, and communication. In each of these sections, we give a brief description, address the issues that are of particular relevance to the application of state-transition models, give specific examples from the literature, and provide best practice recommendations for state-transition modeling. These recommendations are directed both to modelers and to users of modeling results such as clinicians, clinical guideline developers, manufacturers, or policymakers.

Conceptualizing a model: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force--2

The appropriate development of a model begins with understanding the problem that is being represented. The aim of this article was to provide a series of consensus-based best practices regarding the process of model conceptualization. For the purpose of this series of articles, we consider the development of models whose purpose is to inform medical decisions and health-related resource allocation questions. We specifically divide the conceptualization process into two distinct components: the conceptualization of the problem, which converts knowledge of the health care process or decision into a representation of the problem, followed by the conceptualization of the model itself, which matches the attributes and characteristics of a particular modeling type with the needs of the problem being represented. Recommendations are made regarding the structure of the modeling team, agreement on the statement of the problem, the structure, perspective, and target population of the model, and the interventions and outcomes represented. Best practices relating to the specific characteristics of model structure and which characteristics of the problem might be most easily represented in a specific modeling method are presented. Each section contains a number of recommendations that were iterated among the authors, as well as among the wider modeling taskforce, jointly set up by the International Society for Pharmacoeconomics and Outcomes Research and the Society for Medical Decision Making.

The effects of HIV medications on the quality of life of older adults in New York City

A three-equation model is used to estimate the multiple effects of antiretroviral medications (ARVs) on the quality of life (QoL) of the elderly with HIV in New York City. The transmission mechanism involves the ARVs having a direct effect on QoL via the side effects of the medications and two other effects (one indirect and one reverse) both working through feelings of depression. On a scale of 0 to 100, ARVs raise the QoL by 1 percentage point. This was because there was a large positive indirect effect of ARVs on QoL of 28 percentage points via the reduction in depression, which offsets both the 24 percentage-point reduction due to the direct effect and the 3 percentage-point decline from the reverse effect. Now, QoL effects can be applied to the additional life years generated by ARVs to form the quality adjusted life years outcome measure for use in economic evaluations of ARVs.

Cost-effectiveness of raltegravir in HIV/AIDS

Raltegravir is a first-in-class HIV-1 integrase inhibitor with established antiviral efficacy in treatment-naive and treatment-experienced patients with multidrug-resistant HIV-1 infection. In this article, we summarize pharmacoeconomic evaluations of raltegravir-based treatment regimens, compared with alternative therapies, in the treatment of patients with HIV infection and/or AIDS. Cost-effectiveness evaluations of raltegravir in treatment-experienced patients conducted using a continuous-time, state-transition Markov cohort model suggest that raltegravir, combined with optimized background therapy, falls within the range that would generally be considered cost effective compared with optimized therapy alone in Spanish, Swiss and UK health systems. In treatment-naive populations, raltegravir was evaluated using a three-stage continuous-time state-transition cohort model. Raltegravir-based initiation treatment strategies (first-line raltegravir) were compared with protease inhibitor and non-nucleoside reverse-transcriptase inhibitor initiation strategies, in which raltegravir was retained for salvage therapy. First-line raltegravir was cost-effective versus retaining raltegravir for salvage therapy in several European populations. A separate economic model was used to evaluate first-line raltegravir against two alternative initiation regimens representing standard clinical practice in Australia; raltegravir proved to be cost effective in both scenarios. In all studies examined, results were sensitive to factors including treatment duration, mortality rate, analytic time horizon, health utility weights, cost of raltegravir and optimized therapy, incidence of opportunistic infection and discount rates. Nonetheless, raltegravir remained cost effective under most scenarios.

The cost-effectiveness of screening for anal cancer in men who have sex with men: a systematic review

Anal cancer is a relatively rare neoplasm, related to human papillomavirus (HPV), with an incidence that does not warrant general screening. However, as many cases occur in identifiable high-risk populations, targeting these groups may be cost-effective. Screening for anal cancer in men who have sex with men (MSM) may be appropriate, given their elevated risk of anal cancer. Examining existing cost-effectiveness analyses can help inform the design and conduct of future clinical and economic studies. A review of the literature was performed using three databases to identify studies that assessed the cost-effectiveness of anal cancer screening in MSM. Five analyses were identified: four modelled the cost-effectiveness of cytological screening over a patient’s lifetime, and estimated final health outcomes as survival or quality adjusted survival. The fifth presented a decision analysis with intermediate health outcomes only and did not extrapolate to longer-term health outcomes. Several factors influenced the incremental cost-effectiveness ratios. These factors were related to a paucity of primary data and included: availability of longer-term epidemiological and natural history data; availability of utility-based quality of life data from an appropriate respondent population; appropriate resource use information; and availability of information on screening adherence. There is considerable uncertainty in model results: analyses from the United States suggest screening is almost always cost-effective; analyses from the United Kingdom suggest that screening is unlikely to be cost-effective. Uncertainty is primarily driven by data paucity; by summarising key uncertainties in existing models, this review can inform the design and conduct of future studies.

Resource utilization and cost-effectiveness of counselor- vs. provider-based rapid point-of-care HIV screening in the emergency department

Background

Routine HIV screening in emergency department (ED) settings may require dedicated personnel. We evaluated the outcomes, costs and cost-effectiveness of HIV screening when offered by either a member of the ED staff or by an HIV counselor.

Methods

We employed a mathematical model to extend data obtained from a randomized clinical trial of provider- vs. counselor-based HIV screening in the ED. We compared the downstream survival, costs, and cost-effectiveness of three HIV screening modalities: 1) no screening program; 2) an ED provider-based program; and 3) an HIV counselor-based program. Trial arm-specific data were used for test offer and acceptance rates (provider offer 36%, acceptance 75%; counselor offer 80%, acceptance 71%). Undiagnosed HIV prevalence (0.4%) and linkage to care rates (80%) were assumed to be equal between the screening modalities. Personnel costs were derived from trial-based resource utilization data. We examined the generalizability of results by conducting sensitivity analyses on offer and acceptance rates, undetected HIV prevalence, and costs.

Results

Estimated HIV screening costs in the provider and counselor arms averaged $8.10 and $31.00 per result received. The Provider strategy (compared to no screening) had an incremental cost-effectiveness ratio of $58,700/quality-adjusted life year (QALY) and the Counselor strategy (compared to the Provider strategy) had an incremental cost-effectiveness ratio of $64,500/QALY. Results were sensitive to the relative offer and acceptance rates by strategy and the capacity of providers to target-screen, but were robust to changes in undiagnosed HIV prevalence and programmatic costs.

Conclusions

The cost-effectiveness of provider-based HIV screening in an emergency department setting compares favorably to other US screening programs. Despite its additional cost, counselor-based screening delivers just as much return on investment as provider based-screening. Investment in dedicated HIV screening personnel is justified in situations where ED staff resources may be insufficient to provide comprehensive, sustainable screening services.

The Direct Medical Costs of Late Presentation (<350/mm) of HIV Infection over a 15-Year Period

We describe the immediate- and longer-term direct medical costs of care for individuals diagnosed with HIV at CD4 counts <350/mm(3) ("late presenters"). We collected and stratified by initial CD4 count all inpatient, outpatient, and drug costs for all newly diagnosed patients accessing HIV care within Southern Alberta from 1/1/1995 to 1/1/2010. 59% of new patients were late presenters. We found significantly higher costs for late presenters, especially inpatient costs, during the first year after accessing care. Direct medical costs remained almost twice as high for late presenters in subsequent years compared to patients presenting with CD4 counts >350/mm(3) despite significantly their improved CD4 counts. The sustained high cost for late presenters has implications for recent recommendations for wider routine HIV testing and the earlier initiation of cART. Earlier diagnosis and treatment, while increasing the immediate expenditures within a population, may produce both direct and indirect cost savings in the longer term.