Access to Federally Qualified Health Centers and HIV Outcomes in the U.S. South

INTRODUCTION

Federally Qualified Health Centers may increase access to HIV prevention, care, and treatment for at-risk populations.

METHODS

A pooled cross section of ZIP Code Tabulation Areas from cites in the U.S. South with high HIV diagnoses were used to examine Federally Qualified Health Center density and indicators of HIV epidemic control. The explanatory variable was Federally Qualified Health Center density-number of Federally Qualified Health Centers in a ZIP Code Tabulation Areas' Primary Care Service Area per low-income population-high versus medium/low (2019). Outcomes were 5-year (2015-2019 or 2014-2018) (1) number of new HIV diagnoses, (2) percentage late diagnosis, (3) percentage linked to care, and (4) percentage virally suppressed, which was assessed over 1 year (2018 or 2019). Multiple linear regression was used to examine the relationship, including ZIP Code Tabulation Area-level sociodemographic and city-level HIV funding variables, with state-fixed effects, and data analysis was completed in 2022-2023. Sensitivity analyses included (1) examining ZIP Code Tabulation Areas with fewer non-Federally Qualified Health Center primary care providers, (2) controlling for county-level primary care provider density, (3) excluding the highest HIV prevalence ZIP Code Tabulation Areas, and (4) excluding Florida ZIP Code Tabulation Areas.

RESULTS

High-density ZIP Code Tabulation Areas had a lower percentage of late diagnosis and virally suppressed, a higher percentage linked to care, and no differences in new HIV diagnoses (p<0.05). In adjusted analysis, high density was associated with a greater number of new diagnoses (number or percentage=5.65; 95% CI=2.81, 8.49), lower percentage of late diagnosis (-3.71%; 95% CI= -5.99, -1.42), higher percentage linked to care (2.13%; 95% CI=0.20, 4.06), and higher percentage virally suppressed (1.87%; 95% CI=0.53, 2.74) than medium/low density.

CONCLUSIONS

Results suggest that access to Federally Qualified Health Centers may benefit community-level HIV epidemic indicators.

The economic costs and cost-effectiveness of HIV self-testing among truck drivers in Kenya

HIV status awareness is critical for ending the HIV epidemic but remains low in high-HIV-risk and hard-to-reach sub-populations. Targeted, efficient interventions are needed to improve HIV test-uptake. We examined the incremental cost-effectiveness of offering the choice of self-administered oral HIV-testing (HIVST-Choice) compared with provider-administered testing only [standard-of-care (SOC)] among long-distance truck drivers. Effectiveness data came from a randomized-controlled trial conducted at two roadside wellness clinics in Kenya (HIVST-Choice arm, n = 150; SOC arm, n = 155). Economic cost data came from the literature, reflected a societal perspective and were reported in 2020 international dollars (I$), a hypothetical currency with equivalent purchasing power as the US dollar. Generalized Poisson and linear gamma regression models were used to estimate effectiveness and incremental costs, respectively; incremental effectiveness was reported as the number of long-distance truck drivers needing to receive HIVST-Choice for an additional HIV test-uptake. We calculated the incremental cost-effectiveness ratio (ICER) of HIVST-Choice compared with SOC and estimated 95% confidence intervals (CIs) using non-parametric bootstrapping. Uncertainty was assessed using deterministic sensitivity analysis and the cost-effectiveness acceptability curve. HIV test-uptake was 23% more likely for HIVST-Choice, with six individuals needing to be offered HIVST-Choice for an additional HIV test-uptake. The mean per-patient cost was nearly 4-fold higher in HIVST-Choice (I$39.28) versus SOC (I$10.80), with an ICER of I$174.51, 95% CI [165.72, 194.59] for each additional test-uptake. HIV self-test kit and cell phone service costs were the main drivers of the ICER, although findings were robust even at highest possible costs. The probability of cost-effectiveness approached 1 at a willingness-to-pay of I$200 for each additional HIV test-uptake. HIVST-Choice improves HIV-test-uptake among truck drivers at low willingness-to-pay thresholds, suggesting that HIV self-testing is an efficient use of resources. Policies supporting HIV self-testing in similar high risk, hard-to-reach sub-populations may expedite achievement of international targets.

Urban-rural disparities in geographic accessibility to care for people living with HIV

In the United States, people living with HIV (PLWH) in rural areas fare worse along the HIV care continuum than their urban counterparts; this may be due in part to limited geographic access to care. We estimated drive time to care for PLWH, focusing on urban-rural differences. Adult Medicaid enrollees living with HIV and their usual care clinicians were identified using administrative claims data from 14 states (Medicaid Analytic eXtract, 2009-2012). We used geographic network analysis to calculate one-way drive time from the enrollee's ZIP code tabulation area centroid to their clinician's practice address, then examined urban-rural differences using bivariate statistics. Additional analyses included altering the definition of rurality; examining subsamples based on the state of residence, services received, and clinician specialty; and adjusting for individual and county characteristics. Across n = 49,596 PLWH, median drive time to care was 12.8 min (interquartile range 26.3). Median drive time for rural enrollees (43.6 (82.0)) was nearly four times longer than for urban enrollees (11.9 (20.6) minutes, p < 0.0001), and drive times exceeded one hour for 38% of rural enrollees (versus 12% of urban, p < 0.0001). Urban-rural disparities remained in all additional analyses. Sustained efforts to circumvent limited geographic access to care are critical for rural areas.

Disparities in access to primary care, a key site for HIV prevention services, among gay and bisexual men in the United States

U.S. HIV diagnoses disproportionately affect Non-Hispanic Black (NHB) and Hispanic gay and bisexual men. Using data from the National Health Interview Survey (2013-2018), we examined race and ethnicity and primary care access, an HIV prevention resource, among gay and bisexual men. The explanatory variable was NHB, Hispanic or Non-Hispanic White (NHW). Outcomes were primary care-specific usual place of care (potential access) and saw general doctor <12 months (realized access). We used multivariable logistic regression, adjusting for individual sociodemographic characteristics, health status, and care barriers. In sensitivity analysis, we examined general access (any place/doctor) and subgroups (1) NHB (2) has usual place of care. The sample included 1,858 adult, gay and bisexual men (unweighted). Nearly one-third self-identified as NHB or Hispanic. Compared to NHW men, NHB and Hispanic men were younger, with lower household income, and more care barriers (p < 0.05). NHB and Hispanic men had lower realized access (aOR 0.7058, p = 0.030) than NHW men. Potential access was lower for NHB only (versus NHW) and, among those with any usual place of care, NHB and Hispanic men versus NHW men. Lower primary care access for NHB or Hispanic, rather than NHW, gay and bisexual men, may reduce HIV prevention access.

Economic costs and cost-effectiveness of conditional cash transfers for the uptake of services for the prevention of vertical HIV transmissions in a resource-limited setting

BACKGROUND

Prevention of mother-to-child transmission (PMTCT) is critical for halting the HIV epidemic. However, innovative approaches to improve PMTCT uptake may be resource-intensive. We examined the economic costs and cost-effectiveness of conditional cash transfers (CCTs) for the uptake of PMTCT services in the Democratic Republic of Congo.

METHODS

We leveraged data from a randomized controlled trial of CCTs (n = 216) versus standard PMTCT care alone (standard of care (SOC), n = 217). Economic cost data came from multiple sources, with costs analyzed from the societal perspective and reported in 2016 international dollars (I$). Effectiveness outcomes included PMTCT uptake (i.e., accepting all PMTCT visits and services) and retention (i.e., in HIV care at six weeks post-partum). Generalized estimating equations estimated effectiveness (relative risk) and incremental costs, with incremental effectiveness reported as the number of women needing CCTs for an additional PMTCT uptake or retention. We evaluated the cost-effectiveness of the CCTs at various levels of willingness-to-pay and assessed uncertainty using deterministic sensitivity analysis and cost-effectiveness acceptability curves.

RESULTS

Mean costs per participant were I$516 (CCTs) and I$431 (SOC), representing an incremental cost of I$85 (95% CI: 59, 111). PMTCT uptake was more likely for CCTs vs SOC (68% vs 53%, p < 0.05), with seven women needing CCTs for each additional PMTCT service uptake; twelve women needed CCTs for an additional PMTCT retention. The incremental cost-effectiveness of CCTs vs SOC was I$595 (95% CI: I$550, I$638) for PMTCT uptake and I$1028 (95% CI: I$931, I$1125) for PMTCT retention. CCTs would be an efficient use of resources if society's willingness-to-pay for an additional woman who takes up PMTCT services is at least I$640. In the worst-case scenario, the findings remained relatively robust.

CONCLUSIONS

Given the relatively low cost of the CCTs, policies supporting CCTs may decrease onward HIV transmission and expedite progress toward ending the epidemic.

Brief Report: Physician Reimbursement and Retention in HIV Care: Racial Disparities in the US South

BACKGROUND

Retention in HIV care remains a national challenge. Addressing structural barriers to care may improve retention. We examined the association between physician reimbursement and retention in HIV care, including racial differences.

METHODS

We integrated person-level administrative claims (Medicaid Analytic eXtract, 2008-2012), state Medicaid-to-Medicare physician fee ratios (Urban Institute, 2008, 2012), and county characteristics for 15 Southern states plus District of Columbia. The fee ratio is a standardized measure of physician reimbursement capturing Medicaid relative to Medicare physician reimbursement across states. Generalized estimating equations assessed the association between the fee ratio and retention (≥2 care markers ≥90 days apart in a calendar year). Stratified analyses assessed racial differences. We varied definitions of retention, subsamples, and definitions of the fee ratio, including the fee ratio at parity.

RESULTS

The sample included 55,237 adult Medicaid enrollees with HIV (179,002 enrollee years). Enrollees were retained in HIV care for 76.6% of their enrollment years, with retention lower among non-Hispanic Black (76.1%) versus non-Hispanic White enrollees (81.3%, P < 0.001). A 10-percentage point increase in physician reimbursement was associated with 4% increased odds of retention (adjusted odds ratio 1.04, 95% confidence interval: 1.01 to 1.07). In stratified analyses, the positive, significant association occurred among non-Hispanic Black (1.08, 1.05-1.12) but not non-Hispanic White enrollees (0.87, 0.74-1.02). Findings were robust across sensitivity analyses. When the fee ratio reached parity, predicted retention increased significantly overall and for non-Hispanic Black enrollees.

CONCLUSION

Higher physician reimbursement may improve retention in HIV care, particularly among non-Hispanic Black individuals, and could be a mechanism to promote health equity.

Human Immunodeficiency Virus-Experienced Clinician Workforce Capacity: Urban-Rural Disparities in the Southern United States

BACKGROUND

Human immunodeficiency virus (HIV)-experienced clinicians are critical for positive outcomes along the HIV care continuum. However, access to HIV-experienced clinicians may be limited, particularly in nonmetropolitan areas, where HIV is increasing. We examined HIV clinician workforce capacity, focusing on HIV experience and urban-rural differences, in the Southern United States.

METHODS

We used Medicaid claims and clinician characteristics (Medicaid Analytic eXtract [MAX] and MAX Provider Characteristics, 2009-2011), county-level rurality (National Center for Health Statistics, 2013), and diagnosed HIV cases (AIDSVu, 2014) to assess HIV clinician capacity in 14 states. We assumed that clinicians accepting Medicaid approximated the region's HIV workforce, since three-quarters of clinicians accept Medicaid insurance. HIV-experienced clinicians were defined as those providing care to ≥ 10 Medicaid enrollees over 3 years. We assessed HIV workforce capacity with county-level clinician-to-population ratios, using Wilcoxon-Mann-Whitney tests to compare urban-rural differences.

RESULTS

We identified 5012 clinicians providing routine HIV management, of whom 28% were HIV-experienced. HIV-experienced clinicians were more likely to specialize in infectious diseases (48% vs 6%, P < .001) and practice in urban areas (96% vs 83%, P < .001) compared to non-HIV-experienced clinicians. The median clinician-to-population ratio for all HIV clinicians was 13.3 (interquartile range, 38.0), with no significant urban-rural differences. When considering HIV experience, 81% of counties had no HIV-experienced clinicians, and rural counties generally had fewer HIV-experienced clinicians per 1000 diagnosed HIV cases (P < .001).

CONCLUSIONS

Significant urban-rural disparities exist in HIV-experienced workforce capacity for communities in the Southern United States. Policies to improve equity in access to HIV-experienced clinical care for both urban and rural communities are urgently needed.

The effects of community-based distribution of family planning services on contraceptive use: The case of a national scale-up in Malawi

RATIONALE

Although many sub-Saharan African countries have scaled-up pilot projects of community-based distribution (CBD) of family planning services, the effects of the scaled-up CBDs on contraceptive use remain unclear.

OBJECTIVE

We leveraged a national scale-up of Malawi's Learning and Innovation Population and Family Planning pilot to evaluate the effects of a scale-up of CBDs on contraceptive use. We also investigated whether education and income, two important determinants of contraceptive use behaviors, moderate the effects of the scaled-up CBDs.

METHOD

We used the 2000/2004 and 2010/2016 Malawi Demographic and Health Surveys (N = 57,978) and difference-in-differences analyses to estimate the effects of the 2005 national scale-up of CBDs on modern contraceptive use. We used rural and urban communities as the intervention and comparison groups because the national CBDs were implemented only in rural communities. Contraceptive use is defined as the current use of any modern contraceptive method (e.g., pills) and was modelled using multilevel logistic regression.

RESULTS

Prior to the implementation of the national scale CBDs (2000/2004), the probability of using contraceptives was 21.5% in rural communities and 26.3% in urban communities. After the scale-up (2010/2016), the probability of using contraceptives increased in both rural and urban communities but was greater in rural communities (44.9% vs. 42.9%). The effect attributable to the national scale CBDs was 6.8 percentage points (95% CI [3.3, 9.7]). The effects of the national CBDs were greater among uneducated and low-income women.

CONCLUSIONS

These findings suggest that national CBDs increase overall contraceptive use, particularly in rural communities, and that poor and uneducated women benefit more from family planning interventions that reduce communication and financial barriers.

Implementation of "Treat-all" at adult HIV care and treatment sites in the Global IeDEA Consortium: results from the Site Assessment Survey

INTRODUCTION

Since 2015, the World Health Organization (WHO) has recommended that all people living with HIV (PLHIV) initiate antiretroviral treatment (ART), irrespective of CD4+ count or clinical stage. National adoption of universal treatment has accelerated since WHO's 2015 "Treat All" recommendation; however, little is known about the translation of this guidance into practice. This study aimed to assess the status of Treat All implementation across regions, countries, and levels of the health care delivery system.

METHODS

Between June and December 2017, 201/221 (91%) adult HIV treatment sites that participate in the global IeDEA research consortium completed a survey on capacity and practices related to HIV care. Located in 41 countries across seven geographic regions, sites provided information on the status and timing of site-level introduction of Treat All, as well as site-level practices related to ART initiation.

RESULTS

Almost all sites (93%) reported that they had begun implementing Treat All, and there were no statistically significant differences in site-level Treat All introduction by health facility type, urban/rural location, sector (public/private) or country income level. The median time between national policy adoption and site-level introduction was one month. In countries where Treat All was not yet adopted in national guidelines, 69% of sites reported initiating all patients on ART, regardless of clinical criteria, and these sites had been implementing Treat All for a median period of seven months at the time of the survey. The majority of sites (77%) reported typically initiating patients on ART within 14 days of confirming diagnosis, with 60% to 62% of sites implementing Treat All in East, Southern and West Africa reporting same-day ART initiation for most patients.

CONCLUSIONS

By mid- to late-2017, the Treat All strategy was the standard of care at almost all IeDEA sites, including rural, primary-level health facilities in low-resource settings. While further assessments of site-level capacity to provide high-quality HIV care under Treat All and to support sustained viral suppression after ART initiation are needed, the widespread introduction of Treat All at the service delivery level is a critical step towards global targets for ending the HIV epidemic as a public health threat.

Suboptimal geographic accessibility to comprehensive HIV care in the US: regional and urban-rural differences

Achieving US state and municipal benchmarks to end the HIV epidemic and promote health equity requires access to comprehensive HIV care. However, this care may not be geographically accessible for all people living with HIV (PLHIV). We estimated county-level drive time and suboptimal geographic accessibility to HIV care across the contiguous US, assessing regional and urban-rural differences. We integrated publicly available data from four federal databases to identify and geocode sites providing comprehensive HIV care in 2015, defined as the co-located provision of core HIV medical care and support services. Leveraging street network, US Census and HIV surveillance data (2014), we used geographic analysis to estimate the fastest one-way drive time between the population-weighted county centroid and the nearest site providing HIV care for counties reporting at least five diagnosed HIV cases. We summarized HIV care sites, county-level drive time, population-weighted drive time and suboptimal geographic accessibility to HIV care, by US region and county rurality (2013). Geographic accessibility to HIV care was suboptimal if drive time was >30 min, a common threshold for primary care accessibility in the general US population. Tests of statistical significance were not performed, since the analysis is population-based. We identified 671 HIV care sites across the US, with 95% in urban counties. Nationwide, the median county-level drive time to HIV care is 69 min (interquartile range (IQR) 66 min). The median county-level drive time to HIV care for rural counties (90 min, IQR 61) is over twice that of urban counties (40 min, IQR 48), with the greatest urban-rural differences in the West. Nationally, population-weighted drive time, an approximation of individual-level drive time, is over five times longer in rural counties than in urban counties. Geographic access to HIV care is suboptimal for over 170,000 people diagnosed with HIV (19%), with over half of these individuals from the South and disproportionately the rural South. Nationally, approximately 80,000 (9%) drive over an hour to receive HIV care. Suboptimal geographic accessibility to HIV care is an important structural barrier in the US, particularly for rural residents living with HIV in the South and West. Targeted policies and interventions to address this challenge should become a priority.

Research priorities to inform "Treat All" policy implementation for people living with HIV in sub-Saharan Africa: a consensus statement from the International epidemiology Databases to Evaluate AIDS (IeDEA)

INTRODUCTION

"Treat All" - the treatment of all people with HIV, irrespective of disease stage or CD4 cell count - represents a paradigm shift in HIV care that has the potential to end AIDS as a public health threat. With accelerating implementation of Treat All in sub-Saharan Africa (SSA), there is a need for a focused agenda and research to identify and inform strategies for promoting timely uptake of HIV treatment, retention in care, and sustained viral suppression and addressing bottlenecks impeding implementation.

METHODS

The Delphi approach was used to develop consensus around research priorities for Treat All implementation in SSA. Through an iterative process (June 2017 to March 2018), a set of research priorities was collectively formulated and refined by a technical working group and shared for review, deliberation and prioritization by more than 200 researchers, implementation experts, policy/decision-makers, and HIV community representatives in East, Central, Southern and West Africa.

RESULTS AND DISCUSSION

The process resulted in a list of nine research priorities for generating evidence to guide Treat All policies, implementation strategies and monitoring efforts. These priorities highlight the need for increased focus on adolescents, men, and those with mental health and substance use disorders - groups that remain underserved in SSA and for whom more effective testing, linkage and care strategies need to be identified. The priorities also reflect consensus on the need to: (1) generate accurate national and sub-national estimates of the size of key populations and describe those who remain underserved along the HIV-care continuum; (2) characterize the timeliness of HIV care and short- and long-term HIV care continuum outcomes, as well as factors influencing timely achievement of these outcomes; (3) estimate the incidence and prevalence of HIV-drug resistance and regimen switching; and (4) identify cost-effective and affordable service delivery models and strategies to optimize uptake and minimize gaps, disparities, and losses along the HIV-care continuum, particularly among underserved populations.

CONCLUSIONS

Reflecting consensus among a broad group of experts, researchers, policy- and decision-makers, PLWH, and other stakeholders, the resulting research priorities highlight important evidence gaps that are relevant for ministries of health, funders, normative bodies and research networks.

Mathematical modelling to inform 'treat all' implementation in sub-Saharan Africa: a scoping review

OBJECTIVE

Despite widespread uptake, only half of sub-Saharan African countries have fully implemented the World Health Organization's 'treat all' policy, hindering achievement of global HIV targets. We examined literature on mathematical modelling studies that sought to inform scale-up and implementation of 'treat all' in sub-Saharan Africa.

METHODS

We conducted a scoping review, a research synthesis to assess emerging evidence and identify gaps, of peer-reviewed literature, extracting study characteristics on 'treat all' policies and assumptions, setting, key populations, outcomes and findings. Studies were narratively summarised and potential gaps characterised.

RESULTS

We identified 16 studies examining 'treat all' alone (n=12) or with expanded testing (n=7) and/or care continuum improvements (n=6). Twelve studies examined 'treat all' for Southern African countries, while none did so for Central Africa. Four included the role of resistance; one evaluated any key population. A range of health and economic outcomes were reported, although fewer studies formally assessed budget impact. Fourteen studies involved co-authors with any in-country affiliation; one study also had co-authors with local government affiliation. Overall, 'treat all' improves health outcomes and is cost-effective compared to deferred HIV treatment; 'treat all' with expanded testing or care continuum improvements may provide further health benefits. However, studies generally used optimistic assumptions about the implementation of expanded testing or care continuum improvements.

CONCLUSIONS

The modelling literature demonstrates improved health and economic benefits of 'treat all'. Using mathematical modelling to inform real-world implementation of 'treat all' requires realistic assumptions about expanded testing and care continuum interventions across a wide range of settings and populations.

Structural barriers to comprehensive, coordinated HIV care: geographic accessibility in the US South

Structural barriers to HIV care are particularly challenging in the US South, which has higher HIV diagnosis rates, poverty, uninsurance, HIV stigma, and rurality, and fewer comprehensive public health programs versus other US regions. Focusing on one structural barrier, we examined geographic accessibility to comprehensive, coordinated HIV care (HIVCCC) in the US South. We integrated publicly available data to study travel time to HIVCCC in 16 Southern states and District of Columbia. We geocoded HIVCCC service locations and estimated drive time between the population-weighted county centroid and closest HIVCCC facility. We evaluated drive time in aggregate, and by county-level HIV prevalence quintile, urbanicity, and race/ethnicity. Optimal drive time was ≤30 min, a common primary care accessibility threshold. We identified 228 service locations providing HIVCCC across 1422 Southern counties, with median drive time to care of 70 min (IQR 64 min). For 368 counties in the top HIV prevalence quintile, median drive time is 50 min (IQR 61 min), exceeding 60 min in over one-third of these counties. Among counties in the top HIV prevalence quintile, drive time to care is six-folder higher for rural versus super-urban counties. Counties in the top HIV prevalence quintiles for non-Hispanic Blacks and for Hispanics have >50% longer drive time to care versus for non-Hispanic Whites. Including another potential care source-publicly-funded health centers serving low-income populations-could double the number of high-HIV burden counties with drive time ≤30 min, representing nearly 35,000 additional people living with HIV with accessible HIVCCC. Geographic accessibility to HIVCCC is inadequate in the US South, even in high HIV burden areas, and geographic and racial/ethnic disparities exist. Structural factors, such as geographic accessibility to care, may drive disparities in health outcomes. Further research on programmatic policies, and evidence-based alternative HIV care delivery models improving access to care, is critical.

Comprehensive Ryan White Assistance and Human Immunodeficiency Virus Clinical Outcomes: Retention in Care and Viral Suppression in a Medicaid Nonexpansion State

Background

Knowledge gaps remain about how the Ryan White human immunodeficiency virus (HIV)/AIDS Program (RW) contributes to health outcomes. We examined the association between different RW service classes and retention in care (RiC) or viral suppression (VS).

Methods

We identified Virginians engaged in any HIV care between 1 January and 31 December 2014. RW beneficiaries were classified by receipt of ≥1 service from 3 classes: Core medical, Support, and insurance and/or direct medication assistance through the AIDS Drug Assistance Program (ADAP). Receipt of all RW classes was defined as comprehensive assistance. We used multivariable logistic regression to compare the odds of RiC and of VS by comprehensive assistance and by RW classes alone and in combination.

Results

Among 13104 individuals, 58% received any RW service and 17% comprehensive assistance. Comprehensive assistance is significantly associated with RiC (adjusted odds ratio [aOR], 8.8 [95% confidence interval {CI}, 7.2-10.8]) and viral suppression (aOR, 3.3 [95% CI, 2.9-3.8]). Receiving any 2 RW classes or Core alone is significantly associated with RiC and VS, with the strength of association decreasing as the number of classes decreases. Recipients of Support alone are significantly less likely to have VS (aOR, 0.75 [95% CI, .59-.96]). For ADAP recipients also receiving Core and/or Support, insurance assistance is significantly associated with VS compared to receiving direct medication only (aOR, 1.6 [95% CI, 1.3-1.9]); this relationship is not significant for those who receive ADAP alone.

Conclusions

Receiving more classes of RW-funded services is associated with improved HIV outcomes. For some populations with insurance, RW-funded services may still be required for optimal health outcomes.

Implementing parallel spreadsheet models for health policy decisions: The impact of unintentional errors on model projections

Background

Spreadsheet software is increasingly used to implement systems science models informing health policy decisions, both in academia and in practice where technical capacity may be limited. However, spreadsheet models are prone to unintentional errors that may not always be identified using standard error-checking techniques. Our objective was to illustrate, through a methodologic case study analysis, the impact of unintentional errors on model projections by implementing parallel model versions.

Methods

We leveraged a real-world need to revise an existing spreadsheet model designed to inform HIV policy. We developed three parallel versions of a previously validated spreadsheet-based model; versions differed by the spreadsheet cell-referencing approach (named single cells; column/row references; named matrices). For each version, we implemented three model revisions (re-entry into care; guideline-concordant treatment initiation; immediate treatment initiation). After standard error-checking, we identified unintentional errors by comparing model output across the three versions. Concordant model output across all versions was considered error-free. We calculated the impact of unintentional errors as the percentage difference in model projections between model versions with and without unintentional errors, using +/-5% difference to define a material error.

Results

We identified 58 original and 4,331 propagated unintentional errors across all model versions and revisions. Over 40% (24/58) of original unintentional errors occurred in the column/row reference model version; most (23/24) were due to incorrect cell references. Overall, >20% of model spreadsheet cells had material unintentional errors. When examining error impact along the HIV care continuum, the percentage difference between versions with and without unintentional errors ranged from +3% to +16% (named single cells), +26% to +76% (column/row reference), and 0% (named matrices).

Conclusions

Standard error-checking techniques may not identify all errors in spreadsheet-based models. Comparing parallel model versions can aid in identifying unintentional errors and promoting reliable model projections, particularly when resources are limited.

Clinical outcomes of HIV care delivery models in the US: a systematic review

With over 1 million people living with HIV, the US faces national challenges in HIV care delivery due to an inadequate HIV specialist workforce and the increasing role of non-communicable chronic diseases in driving morbidity and mortality in HIV-infected patients. Alternative HIV care delivery models, which include substantial roles for advanced practitioners and/or coordination between specialty and primary care settings in managing HIV-infected patients, may address these needs. We aimed to systematically review the evidence on patient-level HIV-specific and primary care health outcomes for HIV-infected adults receiving outpatient care across HIV care delivery models. We identified randomized trials and observational studies from bibliographic and other databases through March 2016. Eligible studies met pre-specified eligibility criteria including on care delivery models and patient-level health outcomes. We considered all available evidence, including non-experimental studies, and evaluated studies for risk of bias. We identified 3605 studies, of which 13 met eligibility criteria. Of the 13 eligible studies, the majority evaluated specialty-based care (9 studies). Across all studies and care delivery models, eligible studies primarily reported mortality and antiretroviral use, with specialty-based care associated with mortality reductions at the clinician and practice levels and with increased antiretroviral initiation or use at the clinician level but not the practice level. Limited and heterogeneous outcomes were reported for other patient-level HIV-specific outcomes (e.g., viral suppression) as well as for primary care health outcomes across all care delivery models. No studies addressed chronic care outcomes related to aging. Limited evidence was available across geographic settings and key populations. As re-design of care delivery in the US continues to evolve, better understanding of patient-level HIV-related and primary care health outcomes, especially across different staffing models and among different patient populations and geographic locations, is urgently needed to improve HIV disease management.

Performance of a mathematical model to forecast lives saved from HIV treatment expansion in resource-limited settings

BACKGROUND

International guidelines recommend HIV treatment expansion in resource-limited settings, but funding availability is uncertain. We evaluated the performance of a model that forecasts lives saved through continued HIV treatment expansion in Haiti.

METHODS

We developed a computer-based, mathematical model of HIV disease and used incidence density analysis of patient-level Haitian data to derive model parameters for HIV disease progression. We assessed the internal validity of model predictions and internally calibrated model inputs when model predictions did not fit the patient-level data. We then derived uncertain model inputs related to diagnosis and linkage to care, pretreatment retention, and enrollment on HIV treatment through an external calibration process that selected input values by comparing model predictions to Haitian population-level data. Model performance was measured by fit to event-free survival (patient level) and number receiving HIV treatment over time (population level).

RESULTS

For a cohort of newly HIV-infected individuals with no access to HIV treatment, the model predicts median AIDS-free survival of 9.0 years precalibration and 6.6 years postcalibration v. 5.8 years (95% confidence interval, 5.1-7.0) from the patient-level data. After internal validation and calibration, 16 of 17 event-free survival measures (94%) had a mean percentage deviation between model predictions and the empiric data of <6%. After external calibration, the percentage deviation between model predictions and population-level data on the number on HIV treatment was <1% over time.

CONCLUSIONS

Validation and calibration resulted in a good-fitting model appropriate for health policy decision making. Using local data in a policy model-building process is feasible in resource-limited settings.

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

Background

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

Methods

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

Results

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

Conclusions

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

Decision maker priorities for providing antiretroviral therapy in HIV-infected South Africans: a qualitative assessment

In resource-limited settings, successful HIV treatment scale-up has been tempered by reports of funding shortfalls. We aimed to determine the priorities, including ethical considerations, of decision makers for HIV antiretroviral programs. We conducted qualitative interviews with 12 decision makers, identified using purposive sampling. Respondents engaged in one-on-one, semi-structured interviews. We developed an interview guide to direct questions about key priorities and motivations for decision making about HIV antiretroviral programs. We evaluated textual data from the interviews to identify themes. Among 12 respondents, 10 (83%) lived and worked in South Africa. Respondents came from Western Cape, Gauteng, and KwaZulu-Natal provinces and worked primarily in urban settings. The respondents supported prioritizing individual patients based on treatment adherence, pregnancy status to prevent maternal-to-child HIV transmission and/or orphans, and severity of illness. However, priorities based on severity of illness varied, with first-come/first-serve, prioritization of the most severely ill, and prioritization of the least severely ill discussed. Respondents opposed prioritizing based on patient socioeconomic characteristics. Other priorities included the number of persons receiving treatment; how treated patients are distributed in the population (e.g., urban/rural); and treatment policy (e.g., number of antiretroviral regimens). Motivations included humanitarian concerns; personal responsibility for individual patients; and clinical outcomes (e.g., patient-level morbidity/mortality, saving lives) and/or social outcomes (e.g., restoring patients as functional family members). Decision makers have a wide range of priorities for antiretroviral provision in South Africa, and the motivations underlying these priorities suggest at times conflicting ethical considerations for providing HIV treatment when resources are limited.

Diagnostic tests in HIV management: a review of clinical and laboratory strategies to monitor HIV-infected individuals in developing countries

We conducted a systematic review on the performance of diagnostic tests for clinical and laboratory monitoring of HIV-infected adults in developing countries. Diagnostic test information collected from computerized databases, bibliographies and the Internet were categorized as clinical (non-laboratory patient information), immunologic (information from immunologic laboratory tests), or virologic (information from virologic laboratory tests). Of the 51 studies selected for the review 28 assessed immunologic tests, 12 virologic tests and seven clinical and immunologic tests. Methods of performance evaluation were primarily sensitivity and specificity for the clinical category and correlation coefficients for immunologic and virologic categories. In the clinical category, the majority of test performance measures was reported as >70% sensitive and >65% specific. In the immunologic category, correlation coefficients ranged from r=0.54 to r=0.99 for different CD4 count enumeration techniques, while correlation for CD4 and total lymphocyte counts was between r=0.23 and r=0.74. In the virologic category, correlation coefficients for different human immunodeficiency virus (HIV) ribonucleic acid (RNA) quantification techniques ranged from r=0.54 to r=0.90. Future research requires consensus on designing studies, and collecting and reporting data useful for decision-makers. We recommend classifying information into clinically relevant categories, using a consistent definition of disease across studies and providing measures of both association and accuracy.

Cost-effectiveness of enfuvirtide in treatment-experienced patients with advanced HIV disease

OBJECTIVE

Enfuvirtide (ENF) has been shown to improve short-term virologic responses when given to highly treatment-experienced patients with advanced HIV disease. Because of the high cost of ENF compared with other antiretroviral agents, our objectives were to determine the potential long-term clinical impact and cost-effectiveness of ENF in these patients.

METHODS

We used a computer simulation model of HIV disease to project life expectancy, quality-adjusted life expectancy, cost, and cost-effectiveness of ENF in treatment-experienced patients. Input data were from the T-20 versus Optimized Regimen Only (TORO) 1 and 2 trials, 2 studies comparing ENF plus an optimized background regimen (OBR) with an OBR alone.

RESULTS

ENF plus an OBR increased projected discounted quality-adjusted life expectancy from 45.4 months with an OBR alone to 54.9 months, a difference of 9.5 quality-adjusted life-months. At the current annual ENF cost of US 18,500 dollars per year (in 2001 US dollars), the incremental cost-effectiveness ratio for ENF plus an OBR was US 69,500 dollars per quality-adjusted life-year (QALY) compared with an OBR alone. When 48-week virologic suppression rates for ENF plus an OBR were varied from a 50% reduction to a 250% increase in the suppression rate attributable to ENF, gains in quality-adjusted life expectancy ranged from 4.5 to 25.9 quality-adjusted life-months compared with an OBR alone, with cost-effectiveness ratios ranging from US 97,900 dollars per QALY to US 52,300 dollars per QALY gained. If ENF is continued after the HIV RNA level returns to the pretreatment baseline, the cost-effectiveness ratio increases to US 168,200 dollars per QALY.

CONCLUSIONS

In highly treatment-experienced patients, ENF plus an OBR provides substantial gains in quality-adjusted life expectancy compared with an OBR alone. Although ENF plus an OBR is less cost-effective than other commonly used interventions in HIV disease, its use may be justified, given the poor prognosis of these patients and their otherwise limited options for antiretroviral therapy.

Routine human immunodeficiency virus testing: an economic evaluation of current guidelines

BACKGROUND

The Centers for Disease Control and Prevention guidelines recommend human immunodeficiency virus (HIV) counseling, testing, and referral for all patients in hospitals with an HIV prevalence of >or=1%. The 1% screening threshold has not been critically examined since HIV became effectively treatable in 1995. Our objective was to evaluate the clinical effect and cost-effectiveness of current guidelines and of alternate HIV prevalence thresholds.

METHODS

We performed a cost-effectiveness analysis using a computer simulation model of HIV screening and disease as applied to inpatients in U.S. hospitals.

RESULTS

At an undiagnosed inpatient HIV prevalence of 1% and an overall participation rate of 33%, HIV screening increased mean quality-adjusted life expectancy by 6.13 years per 1000 inpatients, with a cost-effectiveness ratio of 35,400 dollars per quality-adjusted life-year (QALY) gained. Expansion of screening to settings with a prevalence as low as 0.1% increased the ratio to 64,500 dollars per QALY gained. Increasing counseling and testing costs from 53 dollars to 103 dollars per person still yielded a cost-effectiveness ratio below 100,000 dollars per QALY gained at a prevalence of undiagnosed infection of 0.1%.

CONCLUSION

Routine inpatient HIV screening programs are not only cost-effective but would likely remain so at a prevalence of undiagnosed HIV infection 10 times lower than recommended thresholds. The current HIV counseling, testing, and referral guidelines should now be implemented nationwide as a way of linking infected patients to life-sustaining care.

Expanded screening for HIV in the United States--an analysis of cost-effectiveness

BACKGROUND

Although the Centers for Disease Control and Prevention (CDC) recommend routine HIV counseling, testing, and referral (HIVCTR) in settings with at least a 1 percent prevalence of HIV, roughly 280,000 Americans are unaware of their human immunodeficiency virus (HIV) infection. The effect of expanded screening for HIV is unknown in the era of effective antiretroviral therapy.

METHODS

We developed a computer simulation model of HIV screening and treatment to compare routine, voluntary HIVCTR with current practice in three target populations: "high-risk" (3.0 percent prevalence of undiagnosed HIV infection; 1.2 percent annual incidence); "CDC threshold" (1.0 percent and 0.12 percent, respectively); and "U.S. general" (0.1 percent and 0.01 percent). Input data were derived from clinical trials and observational cohorts. Outcomes included quality-adjusted survival, cost, and cost-effectiveness.

RESULTS

In the high-risk population, the addition of one-time screening for HIV antibodies with an enzyme-linked immunosorbent assay (ELISA) to current practice was associated with earlier diagnosis of HIV (mean CD4 cell count at diagnosis, 210 vs. 154 per cubic millimeter). One-time screening also improved average survival time among HIV-infected patients (quality-adjusted survival, 220.7 months vs. 219.8 months). The incremental cost-effectiveness was 36,000 dollars per quality-adjusted life-year gained. Testing every five years cost 50,000 dollars per quality-adjusted life-year gained, and testing every three years cost 63,000 dollars per quality-adjusted life-year gained. In the CDC threshold population, the cost-effectiveness ratio for one-time screening with ELISA was 38,000 dollars per quality-adjusted life-year gained, whereas testing every five years cost 71,000 dollars per quality-adjusted life-year gained, and testing every three years cost 85,000 dollars per quality-adjusted life-year gained. In the U.S. general population, one-time screening cost 113,000 dollars per quality-adjusted life-year gained.

CONCLUSIONS

In all but the lowest-risk populations, routine, voluntary screening for HIV once every three to five years is justified on both clinical and cost-effectiveness grounds. One-time screening in the general population may also be cost-effective.

Optimal Frequency of Cd4 Cell Count and HIV Rna Monitoring Prior to Initiation of Antiretroviral Therapy in HIV-Infected Patients

Context

Guidelines regarding the frequency of CD4 cell count and HIV RNA monitoring in HIV-infected patients vary, with recommended strategies ranging from every 2 to every 6 months.

Objective

To determine optimal CD4 cell count and HIV RNA monitoring frequency in HIV-infected patients prior to antiretroviral therapy initiation. Design: Cost-effectiveness (CE) analysis using an HIV simulation model incorporating CD4 cell count and HIV RNA as immunological and virological predictors of clinical outcomes.

Setting

Hypothetical clinical setting.

Patients

Simulated cohort based on initial clinical presentation of HIV-infected patients in the US.

Intervention

CD4 cell count and HIV RNA monitoring at frequencies ranging from every 2 to 24 months prior to antiretroviral initiation, as well as accelerated monitoring frequencies as CD4 cell counts approach a specified treatment threshold.

Outcome measures

Life expectancy, quality-adjusted life expectancy and costs.

Results

For patients presenting with median CD4 cell count 546/mm3 and median HIV RNA 4.8 log10 copies/ml, incremental CE ratios ranged from US$37800/quality-adjusted life year (QALY) gained for a constant testing frequency of every 18 months compared with every 24 months, to US$303300/QALY gained for a constant testing frequency of every 2 months compared with every 4 months when starting treatment at a CD4 cell count of 350/mm3. Monitoring every 12 months until a warning CD4 cell count threshold of 450/mm3 followed by every 3 months until 350/mm3 had an incremental CE ratio of US$74700/QALY gained. When starting antiretroviral therapy at CD4 cell count 200/mm3, monitoring every 12 months until 300/mm3 followed by every 2 months until treatment initiation yielded an incremental CE ratio of US$52200/QALY gained compared with the next best strategy. Increasing monitoring frequency as CD4 cell counts approached a treatment threshold yielded greater incremental clinical benefit for less cost than strategies using a constant frequency.

Conclusions

Monitoring HIV-infected patients every 12 months until 100 CD4 cells/mm3 prior to a specified treatment threshold followed by more frequent monitoring every 2 or 3 months until antiretroviral therapy initiation is both more effective and cost-effective than the current standard of care.

Optimal frequency of CD4 cell count and HIV RNA monitoring prior to initiation of antiretroviral therapy in HIV-infected patients

CONTEXT

Guidelines regarding the frequency of CD4 cell count and HIV RNA monitoring in HIV-infected patients vary, with recommended strategies ranging from every 2 to every 6 months.

OBJECTIVE

To determine optimal CD4 cell count and HIV RNA monitoring frequency in HIV-infected patients prior to antiretroviral therapy initiation.

DESIGN

Cost-effectiveness (CE) analysis using an HIV simulation model incorporating CD4 cell count and HIV RNA as immunological and virological predictors of clinical outcomes.

SETTING

Hypothetical clinical setting.

PATIENTS

Simulated cohort based on initial clinical presentation of HIV-infected patients in the US.

INTERVENTION

CD4 cell count and HIV RNA monitoring at frequencies ranging from every 2 to 24 months prior to antiretroviral initiation, as well as accelerated monitoring frequencies as CD4 cell counts approach a specified treatment threshold.

OUTCOME MEASURES

Life expectancy, quality-adjusted life expectancy and costs.

RESULTS

For patients presenting with median CD4 cell count 546/mm3 and median HIV RNA 4.8 log10 copies/ml, incremental CE ratios ranged from US$37800/quality-adjusted life year (QALY) gained for a constant testing frequency of every 18 months compared with every 24 months, to US$303300/QALY gained for a constant testing frequency of every 2 months compared with every 4 months when starting treatment at a CD4 cell count of 350/mm3. Monitoring every 12 months until a warning CD4 cell count threshold of 450/mm3 followed by every 3 months until 350/mm3 had an incremental CE ratio of US$74700/QALY gained. When starting antiretroviral therapy at CD4 cell count 200/mm3, monitoring every 12 months until 300/mm3 followed by every 2 months until treatment initiation yielded an incremental CE ratio of US$52200/QALY gained compared with the next best strategy. Increasing monitoring frequency as CD4 cell counts approached a treatment threshold yielded greater incremental clinical benefit for less cost than strategies using a constant frequency.

CONCLUSIONS

Monitoring HIV-infected patients every 12 months until 100 CD4 cells/mm3 prior to a specified treatment threshold followed by more frequent monitoring every 2 or 3 months until antiretroviral therapy initiation is both more effective and cost-effective than the current standard of care.

Projecting the cost-effectiveness of adherence interventions in persons with human immunodeficiency virus infection

PURPOSE

To explore the cost-effectiveness of interventions to improve adherence to combination antiretroviral therapy in patients with human immunodeficiency virus (HIV) infection.

METHODS

A simulation model of HIV infection, incorporating CD4 cell count and HIV ribonucleic acid levels as predictors of disease progression, was used to estimate the lifetime costs and quality-adjusted life expectancy associated with clinical interventions to improve adherence to antiretroviral therapy (e.g., directly observed therapy, automatic medication dispensers, beepers, portable alarms) in a clinical trial cohort with early disease (mean CD4 count, 350 cells/microL), a clinical trial cohort with advanced disease (mean CD4 count, 87 cells/microL), and an urban cohort (mean CD4 count, 217 cells/microL). Data were from clinical trials, national databases, and published literature.

RESULTS

For relatively healthy patients with early disease, interventions that reduced virologic failure rates by 10% increased quality-adjusted life expectancy by 3.2 months, whereas those that reduced failure by 80% increased quality-adjusted life expectancy by 34.8 months, as compared with standard care. The cost-effectiveness ratio was below 50000 US dollars per quality-adjusted life-year (QALY) for interventions costing 100 US dollars per month provided that failure rates were reduced by at least 10%, and for those costing 500 US dollars per month provided that failure rates were reduced by more than 50%. For both patients with advanced disease and those from an urban cohort, adherence interventions costing about 500 US dollars per month (e.g., directly observed therapy) had to reduce failure by about 25% to have cost-effectiveness ratios below 50000 US dollars per QALY.

CONCLUSION

In patients with lower baseline levels of adherence or advanced disease, even very expensive, moderately effective adherence interventions are likely to confer cost-effectiveness benefits that compare favorably with other interventions.

Prevention of human immunodeficiency virus-related opportunistic infections in France: a cost-effectiveness analysis

A simulation model of human immunodeficiency virus (HIV) disease, which incorporated French data on the progression of HIV disease in the absence of antiretroviral therapy and on cost, was used to determine the clinical impact and cost-effectiveness of different strategies for the prevention of opportunistic infections in French patients who receive highly active antiretroviral therapy (HAART). Compared with use of no prophylaxis, use of trimethoprim-sulfamethoxazole (TMP-SMZ) increased per-person lifetime costs from euro 185,600 to euro 187,900 and quality-adjusted life expectancy from 112.2 to 113.7 months, for an incremental cost-effectiveness ratio of euro 18,700 per quality-adjusted life-year (euro/QALY) gained. Compared with use of TMP-SMZ alone, use of TMP-SMZ plus azithromycin cost euro 23,900/QALY gained; adding fluconazole cost an additional euro 54,500/QALY gained. All strategies that included oral ganciclovir had cost-effectiveness ratios that exceeded euro 100,000/QALY gained. In the era of HAART, on the basis of French data, prophylaxis against Pneumocystis carinii pneumonia, toxoplasmic encephalitis, and Mycobacterium avium complex bacteremia is cost-effective. Prophylaxis against fungal and cytomegalovirus infections is less cost-effective than are other therapeutic options for HIV disease and should remain of lower priority.

Lifetime cost of HIV care in France during the era of highly active antiretroviral therapy

OBJECTIVE

To estimate the treatment and health care costs of HIV infection or AIDS in France during the era of highly active antiretroviral therapy (HAART).

DESIGN

We used a clinical database of HIV-infected patients to calculate the resource use and cost of care for different stages of HIV infection. Costs were incorporated into a computer-based, probabilistic simulation model of the natural history and treatment of HIV infection to estimate the lifetime cost of treating patients with HIV disease.

SETTING

A northern France HIV clinical cohort.

PARTICIPANTS

1232 HIV-infected patients followed from January 1994 through July 1998.

RESULTS

In the absence of an AIDS-defining event, the average total cost of care ranged from 670 euros (1 euro=US $1.19) per person-month in the highest CD4 stratum (>500/microl) to 1060 euros per person-month in the lowest CD4 stratum (< or = 50/microl). The mean cost of care was estimated at 3370 euros per person-month during the initial months around the occurrence of an AIDS-defining event; at 1750 euros per person-month during the period spanning from 2 months after the diagnosis of specific AIDS-defining event to 1 month prior to death; and at 13010 euros per person-month in the final month prior to death. If clinical management of HIV infection began at a CD4 cell count of 378/microl, as in this cohort, the discounted lifetime cost of treating an HIV-infected French patient was estimated at 214000 euros. The undiscounted costs were 309000 euros over a projected life expectancy of 16.4 years.

CONCLUSION

The cost of HIV disease varies widely depending upon the stage of illness. These estimates of stage-specific and lifetime costs of HIV care will assist health policy planners in assessing the burden of disease in the era of HAART and projecting future resource requirements.

Treatment for primary HIV infection: projecting outcomes of immediate, interrupted, or delayed therapy

With limited data available on the optimal treatment of primary HIV infection, disease modeling can be used to project clinical outcomes and inform decision makers. The authors developed a simulation model to evaluate the clinical outcomes and life expectancy projections for three primary HIV infection treatment strategies: 1) continuous antiretroviral therapy (ART) initiated at CD4 count <350 cells/mm(3); 2) continuous ART initiated immediately on diagnosis of primary HIV infection; and 3) ART initiated on diagnosis followed by structured treatment interruption. Projected life expectancies for the three strategies were 23.92, 24.46, and 26.07 years, respectively. The impact of key variables was assessed in sensitivity analysis, with the structured treatment interruption strategy remaining the most effective over a broad range of inputs. The immunologic benefit associated with immediate therapy and the potential for antiretroviral resistance due to structured treatment interruption have the most important impact on the optimal strategy. Based on current data, immediate treatment on diagnosis of primary HIV infection followed by structured treatment interruption will likely yield the best outcome. These results can assist decision makers and those planning clinical trials in defining evidence-based performance measures for primary HIV infection treatment and future trials.

The relationship of preventable opportunistic infections, HIV-1 RNA, and CD4 Cell counts to chronic mortality

BACKGROUND

Both HIV-1 RNA and absolute CD4 cell counts have been identified as important predictors of HIV-1 disease progression and mortality. The independent impact of opportunistic infections on the risk of chronic mortality, defined as death beyond 30 days of an opportunistic infection, has not been studied when controlling for HIV-1 RNA. Our objective was to determine the relationship between a history of any of five preventable opportunistic infections (Pneumocystis carinii pneumonia, Mycobacterium avium complex, toxoplasmosis, cytomegalovirus, and candida esophagitis) and chronic mortality.

METHODS

Using the Multicenter AIDS Cohort Study (MACS) public use data set of 2193 HIV-infected men in four U.S. cities, we employed a Cox regression model to estimate the impact of a history of preventable opportunistic infection on chronic mortality while controlling for maximum HIV-1 RNA, CD4 cell count, use of antiretroviral drugs, and age.

FINDINGS

The chronic mortality rate among individuals with a history of preventable opportunistic infection was 66.7 per 100 person-years compared with 2.3 per 100 person-years for those without a history of preventable opportunistic infection (RR = 28.4, 95% CI: 24.7-32.8). In the adjusted analysis, the relative hazard of death for those with a history of preventable opportunistic infections was 7.0 (5.8-8.3), whereas antiretroviral therapy was associated with a decreased risk of death (0.37 [0.30-0.44]). We found no association between maximum HIV-1 RNA and chronic mortality. There was statistically significant effect modification between preventable opportunistic infections and CD4 cell count (p <.0001).

INTERPRETATION

Preventable opportunistic infections cause not only short-term mortality in HIV-1 disease but appear to have a major impact on chronic mortality.

Lifetime Cost of HIV Care in France during the Era of Highly Active Antiretroviral Therapy

Objective

To estimate the treatment and health care costs of HIV infection or AIDS in France during the era of highly active antiretroviral therapy (HAART).

Design

We used a clinical database of HIV-infected patients to calculate the resource use and cost of care for different stages of HIV infection. Costs were incorporated into a computer-based, probabilistic simulation model of the natural history and treatment of HIV infection to estimate the lifetime cost of treating patients with HIV disease.

Setting

A northern France HIV clinical cohort.

Participants

1232 HIV-infected patients followed from January 1994 through July 1998.

Results

In the absence of an AIDS-defining event, the average total cost of care ranged from 670 euros (1 euro=US $1.19) per person-month in the highest CD4 stratum (>500/μl) to 1060 euros per person-month in the lowest CD4 stratum (≤50/μl). The mean cost of care was estimated at 3370 euros per person-month during the initial months around the occurrence of an AIDS-defining event; at 1750 euros per person-month during the period spanning from 2 months after the diagnosis of specific AIDS-defining event to 1 month prior to death; and at 13 010 euros per person-month in the final month prior to death. If clinical management of HIV infection began at a CD4 cell count of 378/μl, as in this cohort, the discounted lifetime cost of treating an HIV-infected French patient was estimated at 214 000 euros. The undiscounted costs were 309 000 euros over a projected life expectancy of 16.4 years.

Conclusion

The cost of HIV disease varies widely depending upon the stage of illness. These estimates of stage-specific and lifetime costs of HIV care will assist health policy planners in assessing the burden of disease in the era of HAART and projecting future resource requirements.

Prophylaxis for human immunodeficiency virus-related Pneumocystis carinii pneumonia: using simulation modeling to inform clinical guidelines

BACKGROUND

Human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) have experienced a dramatic decrease in Pneumocystis carinii pneumonia (PCP), necessitating reassessment of clinical guidelines for prophylaxis.

METHODS

A simulation model of HIV infection was used to estimate the lifetime costs and quality-adjusted life expectancy (QALE) for alternative CD4 cell count criteria for stopping primary PCP prophylaxis in patients with CD4 cell count increases receiving HAART and alternative agents for second-line PCP prophylaxis in those intolerant of trimethoprim-sulfamethoxazole (TMP/SMX). The target population was a cohort of HIV-infected patients in the United States with initial CD4 cell counts of 350/microL who began PCP prophylaxis after their first measured CD4 lymphocyte count less than 200/microL. Data were from randomized controlled trials and other published literature.

RESULTS

For patients with CD4 cell count increases during HAART, waiting to stop prophylaxis until the first observed CD4 cell count was greater than 300/microL prevented 9 additional cases per 1000 patients and cost $9400 per quality-adjusted life year (QALY) gained compared with stopping prophylaxis at 200/microL. For patients intolerant of TMP/SMX, using dapsone increased QALE by 2.7 months and cost $4500 per QALY compared with no prophylaxis. Using atovaquone rather than dapsone provided only 3 days of additional QALE and cost more than $1.5 million per QALY.

CONCLUSIONS

Delaying discontinuation of PCP prophylaxis until the first observed CD4 cell count greater than 300/microL is cost-effective and provides an explicit "PCP prophylaxis stopping criterion." In TMP/SMX-intolerant patients, dapsone is more cost-effective than atovaquone.

Use of genotypic resistance testing to guide hiv therapy: clinical impact and cost-effectiveness

BACKGROUND

Genotypic sequencing for drug-resistant strains of HIV can guide the choice of antiretroviral therapy.

OBJECTIVE

To assess the cost-effectiveness of genotypic resistance testing for patients acquiring drug resistance through failed treatment (secondary resistance) and those infected with resistant virus (primary resistance).

DESIGN

Cost-effectiveness analysis with an HIV simulation model incorporating CD4 cell count and HIV RNA level as predictors of disease progression.

DATA SOURCES

Published randomized trials and data from the Multicenter AIDS Cohort Study, the national AIDS Cost and Services Utilization Survey, the Red Book, and an institutional cost-accounting system.

TARGET POPULATION

HIV-infected patients in the United States with baseline CD4 counts of 0.250 x 10(9) cells/L.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

Genotypic resistance testing and clinical judgment, compared with clinical judgment alone, in two contexts: after initial treatment failure (secondary resistance testing) and before initiation of antiretroviral therapy (primary resistance testing).

OUTCOME MEASURES

Life expectancy, quality-adjusted life expectancy, and cost-effectiveness in dollars per quality-adjusted life-year (QALY) gained.

RESULTS OF BASE-CASE ANALYSIS

Secondary resistance testing increased life expectancy by 3 months, at a cost of $17 900 per QALY gained. The cost-effectiveness of primary resistance testing was $22 300 per QALY gained with a 20% prevalence of primary resistance but increased to $69 000 per QALY gained with 4% prevalence.

RESULTS OF SENSITIVITY ANALYSIS

The cost-effectiveness ratio for secondary resistance testing remained under $25 000 per QALY gained, even when effectiveness and cost of testing and antiretroviral therapy, quality-of-life weights, and discount rate were varied.

CONCLUSIONS

Genotypic antiretroviral resistance testing following antiretroviral failure is cost-effective. Primary resistance testing also seems to be reasonably cost-effective and will become more so as the prevalence of primary resistance increases.

The cost effectiveness of combination antiretroviral therapy for HIV disease

BACKGROUND

Combination antiretroviral therapy with a combination of three or more drugs has become the standard of care for patients with human immunodeficiency virus (HIV) infection in the United States. We estimated the clinical benefits and cost effectiveness of three-drug antiretroviral regimens.

METHODS

We developed a mathematical simulation model of HIV disease, using the CD4 cell count and HIV RNA level as predictors of the progression of disease. Outcome measures included life expectancy, life expectancy adjusted for the quality of life, lifetime direct medical costs, and cost effectiveness in dollars per quality-adjusted year of life gained. Clinical data were derived from major clinical trials, including the AIDS Clinical Trials Group 320 Study. Data on costs were based on the national AIDS Cost and Services Utilization Survey, with drug costs obtained from the Red Book.

RESULTS

For patients similar to those in the AIDS Clinical Trials Group 320 Study (mean CD4 cell count, 87 per cubic millimeter), life expectancy adjusted for the quality of life increased from 1.53 to 2.91 years, and per-person lifetime costs increased from $45,460 to $77,300 with three-drug therapy as compared with no therapy. The incremental cost per quality-adjusted year of life gained, as compared with no therapy, was $23,000. On the basis of additional data from other major studies, the cost-effectiveness ratio for three-drug therapy ranged from $13,000 to $23,000 per quality-adjusted year of life gained. The initial CD4 cell count and drug costs were the most important determinants of costs, clinical benefits, and cost effectiveness.

CONCLUSIONS

Treatment of HIV infection with a combination of three antiretroviral drugs is a cost-effective use of resources.

Preevaluation of clinical trial data: the case of preemptive cytomegalovirus therapy in patients with human immunodeficiency virus

We developed a mathematical simulation model to anticipate outcomes from an upcoming trial of targeted, preemptive cytomegalovirus (CMV) therapy in high-risk, human immunodeficiency virus (HIV)-infected patients identified by means of CMV polymerase chain reaction screening. We estimated the costs and consequences of CMV prophylaxis in patients with CD4(+) counts < or =100 cells/microL under various assumptions regarding disease progression, complication rates, drug effects, and costs. Without CMV preemptive therapy, lifetime costs average $44,600 with expected duration of survival of 19.16 quality-adjusted life-months and 213 CMV cases per 1000 patients. Targeted preemptive therapy with orally administered valganciclovir increases costs and duration of survival to $46,900 and 19.63 quality-adjusted life-months, respectively. CMV cases decrease to 174 per 1000 patients. The cost per quality-adjusted life-year gained is $59,000. This result compares favorably with other strategies in end-stage HIV disease but hinges on valganciclovir cost and efficacy assumptions and the absence of minimally effective salvage antiretroviral therapy for HIV. The upcoming trial should resolve the clinical uncertainty surrounding some of these assumptions.