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RESEARCH |
At the time of the study Bruce R. Schackman was, and Sue J. Goldie, Milton C. Weinstein, and Kenneth A. Freedberg are now, with the Center for Risk Analysis, Department of Health Policy and Management, Harvard School of Public Health, Boston, Mass. Elena Losina and Dr. Freedberg are with the Department of Epidemiology and Biostatistics, Boston University School of Public Health, Boston. Dr. Losina, Hong Zhang, and Dr. Freedberg are with the Division of General Medicine and Partners AIDS Research Center, Massachusetts General Hospital and Harvard Medical School, Boston.
Correspondence: Requests for reprints should be sent to Bruce R. Schackman, PhD, Department of Public Health, Weill Medical College of Cornell University, 411 East 69th St, New York, NY 10021 (e-mail: brs2006{at}med.cornell.edu).
| ABSTRACT |
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Objectives. This study was designed to examine the societal cost-effectiveness and the impact on government payers of earlier initiation of antiretroviral therapy for uninsured HIV-infected adults.
Methods. A state-transition simulation model of HIV disease was used. Data were derived from the Multicenter AIDS Cohort Study, published randomized trials, and medical care cost estimates for all government payers and for Massachusetts, New York, and Florida.
Results. Quality-adjusted life expectancy increased from 7.64 years with therapy initiated at 200 CD4 cells/µL to 8.21 years with therapy initiated at 500 CD4 cells/µL. Initiating therapy at 500 CD4/µL was a more efficient use of resources than initiating therapy at 200 CD4/µL and had an incremental cost-effectiveness ratio of $17 300 per quality-adjusted life-year gained, compared with no therapy. Costs to state payers in the first 5 years ranged from $5500 to $24 900 because of differences among the states in the availability of federal funds for AIDS drug assistance programs.
Conclusions. Antiretroviral therapy initiated at 500 CD4 cells/µL is cost-effective from a societal perspective compared with therapy initiated later. States should consider Medicaid waivers to expand access to early therapy.
| INTRODUCTION |
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For uninsured, asymptomatic HIV-infected individuals in the United States, the primary sources of payment for antiretroviral therapy have been state-level AIDS Drug Assistance Programs (ADAPs) funded by the federal Ryan White Comprehensive AIDS Resources Emergency (CARE) Act. ADAPs usually do not cover nondrug services such as HIV RNA (viral load) testing and physician office visits. Moreover, because ADAPs rely on annual appropriations from Congress and state legislatures, coverage varies substantially over time and from state to state. In fiscal year 1998, roughly half of all ADAPs reported budget shortages or program limitations, and approximately 2500 eligible individuals were on waiting lists to enter ADAPs.7
In 1997 a proposal to revise federal Medicaid eligibility rules to include asymptomatic HIV-infected individuals was rejected because it was not budget neutral (i.e., it was projected to increase costs to the federal Medicaid budget over 5 years).8,9 Individual states can still apply to expand Medicaid coverage under a Section 1115 waiver, which requires federal Medicaid budget neutrality, or as a demonstration project under the Ticket to Work and Work Incentives Improvement Act of 1999.5,10,11
We used a computer-based simulation model of HIV disease to estimate the costeffectiveness from a societal perspective and the financial impact on government payers of providing early versus deferred antiretroviral therapy to uninsured HIV-infected individuals who present for medical care with 500 CD4 cells/µL. We also used this model to determine the budgetary implications of these treatment strategies for 3 US states with different levels of federal support for ADAPs.
| METHODS |
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We also evaluated the financial costs of the 3 treatment strategies from the perspective of all government payers, including federal, state, and county governments. We adjusted medication costs to reflect discounts provided by pharmaceutical manufacturers to Medicaid and ADAPs, and we adjusted patient care costs to reflect estimated national average payments by Medicaid and other government payers. We then compared the financial costs of the 3 treatment strategies for state and county government payers in 3 US states with different levels of federal ADAP support: Massachusetts, New York, and Florida. To determine the impact on the state and county payers'; budgets, we used state-specific estimated Medicaid payments and excluded federal contributions to Medicaid and ADAPs. We did not discount future costs in these analyses.
The Model
We used a computer-based state-transition simulation model of the progression of HIV disease.13 The model is programmed in C and compiled in C++ (Microsoft, Seattle, Wash). A hypothetical cohort of 1 million HIV-infected individuals with CD4 cell counts of 500/µL enters the model a person at a time, and each person is followed until death. Live health states are categorized as chronic or acute and are stratified by CD4 cell count and HIV RNA. Patients move from chronic to acute health states when they develop opportunistic infections. Deaths can occur from opportunistic infections, be HIV-related in the chronic health state, or be nonHIV-related.14
The efficacy of an antiretroviral regimen is represented by HIV RNA suppression, which results in an increased CD4 cell count.15 Antiretroviral treatment is considered to have failed when a 0.5 log increase in HIV RNA is observed for 2 consecutive months while the patient is on antiretroviral therapy. Once failure occurs, and after a 6-month delay, patients'; CD4 cell counts begin to decline at a rate based on their original HIV RNA setpoint. The cost and QALY impact of drugspecific toxicities observed in published clinical trials are incorporated into the model.
We assumed that patients were aware of their HIV infection, had never received antiretroviral treatment, lacked private insurance, met financial eligibility requirements for ADAPs and Medicaid, and would remain enrolled in all government programs when they became eligible. Except in the case of a Medicaid waiver, we assumed that all patients initially were enrolled in an ADAP and became eligible for Medicaid on the basis of disability when their CD4 cell count fell below 200/µL (although in fact the determination of eligibility in most states is based on the presence of clinical symptoms).5 We did not take Medicare enrollment into account, because the analysis of the impact on state and county budgets was limited to the first 5 years in a population with early-stage HIV disease.
We evaluated a hypothetical cohort with a mean age of 36 years, based on the age distribution of uninsured patients in the HIV Cost and Services Utilization Study.16 We assumed that the cohort was 80% male, based on the sex distribution of ADAP participants nationally.7
Data
Clinical data.
We derived the HIV RNA setpoint distribution, the average monthly rate of CD4 decline without antiretroviral therapy, and the monthly risks of (1) opportunistic infections, (2) acute mortality, and (3) chronic AIDS mortality from the Multicenter AIDS Cohort Study data set.1720 Although the Multicenter AIDS Cohort Study included mainly White homosexual men, the natural history of HIV infection predicted by the model was consistent with observations among women, nonwhites, and injection drug users.21 Patients received standard opportunistic infection prophylaxis, and their HIV RNA and CD4 cell counts were measured every 3 months.1,22
For the efficacy of initial antiretroviral therapy, we used data from the 3-drug therapy arm of the AIDS Clinical Trials Group Protocol 320, which included indinavir, zidovudine, and lamivudine.23 We modeled efficacy by calibrating monthly HIV RNA levels transition probabilities to the trial';s efficacy results (60% of patients in the 3-drug arm with no detectable HIV RNA below 500 copies/mL at 24 weeks). The efficacy of subsequent 3-drug antiretroviral therapy in patients who experienced treatment failure in their initial regimen was based on data from the Community Programs for Clinical Research on AIDS Protocol 046.24 We used the same modeling approach with efficacy data from the control arm of this study, which included no resistance testing and a variety of second-line regimens selected by treating physicians (22% of patients with no detectable HIV RNA below 500 copies/mL at 12 weeks).24 We assumed that the first- and second-line regimens were each efficacious for 2 years for patients who had not experienced treatment failure in the interim.25 We assumed that all antiretroviral therapy was discontinued at the time of second-line treatment failure. We considered alternative efficacy assumptions, including first-line regimens with better efficacy and additional salvage therapies, in sensitivity analyses.
Costs and quality of life.
Cost input data are summarized in Table 1
. Patient care costs were derived from the AIDS Costs and Services Utilization Survey and were adjusted to include HIV RNA monitoring every 3 months.1,26 For analyses conducted from the societal perspective, we converted charges to estimates of cost by using a national cost-to-charge ratio.13 For analyses conducted from the all-government payer perspective and the state and county budget perspective, we assumed that charges reported in the AIDS Costs and Services Utilization Survey were representative of charges to private payers. We reduced these charges on the basis of published comparisons between physician fee levels or hospital payments by state Medicaid programs and payments by Medicare and by private payers, except in New York (where we used an HIV-specific Medicaid fee schedule for physician services).2729 We converted all patient care costs to 1998 dollars by using the medical care component of the Consumer Price Index.14
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| RESULTS |
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All-Government Payer Perspective
We also explored the financial costs paid by federal, state, and county payers in an analysis from the all-government payer perspective. Over the first 5 years, the undiscounted total direct medical costs per patient to these payers were $29 100 for deferred therapy and $40 600 for early therapy. The undiscounted antiretroviral and prophylaxis medication costs for the first 5 years were $3300 for deferred therapy and $21 500 for early therapy. Thus, in the first 5 years, although drug costs were $18 200 higher for early therapy vs deferred therapy, total costs were only $11 500 higher because of savings from averted HIV-related morbidity (Figure 2
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State and County Payer Budget Impact
We estimated the impact on state and county budgets per enrollee over 5 years for each of the 3 treatment strategies in 3 different states: Massachusetts, New York, and Florida. For each of these states we projected the budget impact under 2 scenarios: (1) all patients were enrolled in a state ADAP program and then were transferred to Medicaid when their CD4 cell counts reached 200/µL (No Medicaid Waiver scenario), and (2) all patients in the cohort were enrolled in Medicaid with CD4 cell counts of 500/µL (Medicaid Waiver scenario).
Table 3
describes the state or county share of government costs incurred under the No Medicaid Waiver and Medicaid Waiver scenarios in each of the 3 states. The No Medicaid Waiver scenario reflects the fact that 2 of the states have established programs that cover nondrug direct medical costs for uninsured HIV-infected individuals. State officials reported to us that ACT NOW in Massachusetts was 100% supported with state funds, and ADAP Plus in New York was 100% supported with federal Ryan White CARE Act funds. In Florida, nondrug expenses for uninsured HIV-infected patients were assumed to be paid for as indigent care at the county level.36 In 1998 the state share of ADAP drug costs was 41% for Massachusetts, 13% for New York, and 8% for Florida.7 For patients enrolled in Medicaid in either scenario, the state share of all costs in 1998 was 50% in Massachusetts and New York and 44% in Florida.37
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In the No Medicaid Waiver scenario in Florida, the 5-year state and county budgetary cost per patient was $20 900 for deferred antiretroviral therapy and $17 400 for early antiretroviral therapy. Early antiretroviral therapy resulted in lower costs per enrollee than deferred therapy because Florida receives a high proportion of drug costs from federal ADAP funds but lacks a specific program to pay for nondrug direct medical costs for ADAP enrollees. In the presence of a Medicaid waiver, the 5-year state and county budgetary cost of early antiretroviral therapy is projected to have been $17 500 per enrollee$100 higher than without a Medicaid waiverbecause Florida pays for a higher proportion of drug costs under Medicaid than it does under ADAP.
| DISCUSSION |
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Differences in federalstate cost-sharing formulas led to substantially different impacts of early and deferred therapy on state and county budgets in the absence of a Medicaid waiver. The cost-sharing formulas also resulted in different impacts of a Medicaid waiver on each state';s budget. In Massachusetts, enrollment of early-stage HIV patients in Medicaid under a waiver would have reduced costs to the state budget and increased costs to the federal Medicaid budget. To achieve federal Medicaid budget neutrality, the state would have to provide additional budget allocations, identify other Medicaid savings, or reduce costs through patient premiums, copayments, or deductibles.
There are several limitations to this analysis. Our assumptions about the efficacy of initial 3-drug combination antiretroviral therapy were based on a clinical trial conducted among patients who had been treated previously with less-effective antiretroviral therapy, which may have resulted in an underestimate of efficacy in a treatment-naive population. On the other hand, the efficacy of antiretroviral therapy reported for a Maryland population with a high proportion of Medicaid participants was substantially lower than that reported in the clinical trial.38 We also assumed that the efficacy of each antiretroviral regimen in achieving viral suppression would not extend beyond 2 years and would not differ between those starting at 500 CD4/µL and those starting at 200 CD4 cells/µL.
The analysis was limited to patients who were financially eligible for both ADAPs and Medicaid, although income eligibility varies by state, and some states (including Florida) periodically have limited access to ADAPs for eligible new enrollees because of budgetary constraints.7 We assumed that all patients became eligible for Medicaid as soon as they had an observed CD4 cell count below 200/µL, although actual eligibility for Medicaid depends on clinical symptoms. This assumption may have led to projections of average Medicaid enrollment at an earlier stage of disease than actually occurs. We also assumed that patients remained in the ADAPs and Medicaid. Even though disenrollment does occur, few HIV-infected patients regain private insurance once they have begun receiving benefits from government programs.39
We assumed that Medicaid cost-to-charge ratios and statefederal cost-sharing ratios for ADAPs would remain consistent over 5 years in the state and county budgetary analysis. From 1997 to 1998, however, the state share of the ADAP budget fell 19% in Massachusetts, fell less than 1% in New York, and increased 3% in Florida.7 Future ADAP budget increases may be allocated in ways that significantly alter these ratios. We assumed that nondrug costs for ADAP enrollees were covered only by supplementary ADAPs or indigent care, although some of these services also are provided by other programs supported by Ryan White Act Title I and non-ADAP Title II federal funds.
The analysis was restricted to a cohort of patients at the same early stage of disease. We did not simulate a population of patients with a distribution of CD4 values that would match patients who currently are eligible for state assistance or those who are newly diagnosed. We also did not estimate the impact on state budgets of expanding coverage to a population of patients who are not currently in treatment. Any expansion of services to early-stage HIV-infected individuals who are not currently in treatment will result in added expenses for state budgets in the short term. Because the focus of this analysis was on financial cost per patient, the analysis also did not take into account the greater potential financial security to beneficiaries of transferring their insurance coverage to an entitlement program, nor did it capture potential savings deriving from the possibility that patients receiving antiretroviral therapy would be less likely to infect others.
Using the cost-effectiveness framework, we found that early antiretroviral therapy for uninsured HIV-infected adults with CD4 cell counts of 500/µL had a cost-effectiveness ratio that was between those reported for Pneumocystis carinii pneumonia prophylaxis ($2500 per QALY in 1998 US dollars) and Mycobacterium avium complex prophylaxis ($38 400 per QALY in 1998 US dollars), both of which are considered "standard of care" in HIV treatment.13 The cost-effectiveness ratio also was below the median published cost-effectiveness ratio for all medical interventions ($22 800 in 1998 US dollars).40 Thus, early antiretroviral therapy appears to offer good value for resources spent. Some states should consider programs to expand access to early antiretroviral therapy in accordance with current treatment guidelines through Medicaid waivers or other Medicaid demonstration projects. The budgetary impact of these programs will vary substantially by state, however, and states will need to carefully assess their attractiveness in the context of future statefederal cost-sharing plans.
| Acknowledgments |
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| Footnotes |
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Accepted for publication October 6, 2000.
| References |
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