Combination antiretroviral therapy in HIV infection. An economic perspective

HIV Patients in the HCUP Database: A Study of Hospital Utilization and Costs

This study examines the utilization of hospital care by HIV patients in all hospitals in eight states (California, Colorado, Florida, Kansas, New Jersey, New York, Pennsylvania, and South Carolina), and examines the cost of hospital care for HIV patients in six of these states (California, Colorado, Kansas, New Jersey, New York, and South Carolina). The eight states in the sample account for more than 52% of all persons living with AIDS in the United States; the six states account for 39%. The unit of observation in both studies is a hospital admission by a patient with HIV. Hospital data were obtained from the Healthcare Cost and Utilization Project (HCUP), State Inpatient Database (SID), which is maintained by the Agency for Healthcare Research and Quality (AHRQ). The HCUP contains hospital discharge data and is a federal/state/industry partnership to build a multistate health care data system. Using multivariate analytic techniques and data from 2000, results indicate that cost and length of a hospital stay vary significantly across states after accounting for a patient's gender, insurance type, race, age, and number of diagnoses, as well as the teaching status and ownership category of the hospital.

Impact of Protease Inhibitors on Drug Use and Cost for Hospital Patients with HIV

Objective:

To evaluate the impact of protease inhibitors on drug cost and frequency of admission-defining events for HIV-infected patients in the infectious diseases unit of F Houphouët Boigny Hospital in Marseilles, France, which provides conventional hospitalization and outpatient care.

Methods:

Data from a prospective eight-year study conducted from January 1, 1990, to December 31, 1997, were used. Data from nurse records were collected daily by a pharmacy resident. Statistical analyses were performed to compare 1997 data with previous years, since protease inhibitors were not available in France until March 1996.

Results:

A total of 1,558 inpatients, accounting for 2,717 admissions, participated in the study. From 1995 to 1997, we observed a decrease in the percentage of hospitalized patients compared with the total number of patients (48.8%). We also noticed a reduction in number of stays (52%) and mean duration of stays (from 16.06 ± 1.81 to 11.08 ± 1.80 d). Total drug cost in the inpatient care unit dropped by one-half (based on 100 patients/y). The number of hospital admissions and mean drug cost per stay also decreased for some opportunistic infections described as late complications of AIDS; at the same time, drug costs in the outpatient unit rose sharply.

Conclusions:

This study confirms recent advances in HIV management. Use of protease inhibitors has reduced the relative risk of opportunistic infections and cost of inpatient treatment. This reduction has been associated with a sharp cost increase for outpatient therapy, resulting from widespread use of protease inhibitors.

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

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

Pharmacoeconomic evaluation of intensified antiretroviral treatment strategies in HIV/AIDS

There have been great technological advances in the use of antiretroviral therapies to slow down disease progression in HIV/AIDS. Combinations of therapeutics and the use of several diagnostic methods have resulted in both declines in mortality and the occurrence of opportunistic infections. The higher costs of these therapeutics have prompted questions about the economic aspects of treatment with antiretrovirals. In this review, we provide an overview of the research that has been published on this topic and list the important outcomes and methodological issues associated with the different therapies.

Cost to achieve an undetectable viral load using recommended antiretroviral regimens

PURPOSE

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

METHOD

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

RESULTS

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

CONCLUSION

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

Economic models of antiretroviral therapy: searching for the optimal strategy

The diffusion of protease inhibitors and non-nucleoside reverse transcriptase inhibitors in the US in 1996 and 1997 reduced the number of deaths attributable to HIV disease and changed the way we think about the illness. Today, HIV disease may be deemed a fairly expensive chronic condition rather than an intolerably expensive fatal illness. Although most studies have found that patients receiving new drug therapies are hospitalised less frequently than patients who received early drug therapies, it is unclear whether the diffusion of new drug therapies has increased or decreased the annual cost of care. However, it is evident that the diffusion of new drug therapies has increased the lifetime cost of care. Analysts rely on models to simulate the course and cost of HIV disease. This study reviews the evolution of these models, paying particular attention to how these models estimate the cost of care. The primary findings of this review are that the economic data used in these models are often too imprecise to accurately identify the cost of each disease stage and are almost always outdated. Moreover, it was found that estimates of drug costs in these models may not accurately reflect actual expenditures.

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.

Cost-effectiveness league tables: valuable guidance for decision makers?

This paper asks the question 'are cost-effectiveness league tables a good way to provide information to decision makers about the value of new healthcare interventions?' League tables that rank alternative healthcare interventions based on their incremental cost-effectiveness ratios (ICERs) are seen by economists as a valuable tool to inform decision makers about the allocation of scarce healthcare resources. However, league tables frequently compare ICERs from studies that have computed these ratios using different methods and assumptions including choice of comparator, choice of discount rate, time horizon, and population subgroup. The methodological differences among studies may influence the ranking of the studies and therefore decisions made using the league table. In addition, league tables generally do not include measures of the uncertainty of the cost-effectiveness estimates. In this paper, a reference case approach is proposed for the computation of the incremental cost-effectiveness ratio and an expanded set of measures is proposed for inclusion in the league table. In addition, a central repository for reference case expanded league tables is suggested so that decision makers can use them more effectively and more consistently.

A Comparison of the Therapeutic Plan Costs in the Treatment of HIV-Positive Patients

OBJECTIVE

To determine the cost of each therapeutic protocol (TP) used for HIV-positive patients and to identify the most frequently adopted one by relating it to the cost and by identifying the drug (drugs) that is more competitive in relation to expense.

SETTING

Infectious Disease Department and Hospital Pharmacy, Ospedale Maggiore, Bologna, Italy. The department treats approximately 600 outpatients with HIV infection each year.

PATIENTS AND METHODS

464 patients with HIV infection were examined every 3 months and clinicians judged whether the treatment (usually consisting of three drugs) was to be continued or changed according to its effectiveness, availability and possible new treatment options. The study also ascertained the cost of antiretroviral drugs within the period 1 January 2001-30 April 2002, and identified the most commonly used therapeutic protocols, the relevant daily cost and the frequency of use in all patients. The cost of the various protocols (most TPs were grouped in the most frequently used 15 regimens) was considered only at the end of the study, in order to define the percentage differences in cost. Importantly, from the beginning, this aspect was not a primary factor in drug choice.

RESULTS

The antiretroviral drug cost was 4 448 186 Euro (euro) in 2001 and euro1 536 984 in the first 4 months of 2002, with an increase of 3.5% compared with the same period in 2001. In the 16 months under consideration, 55.21% of the cost was associated with nucleoside reverse transcriptase inhibitors (NRTI), 25.97% with protease inhibitors (PI) and 18.83% with non-nucleoside reverse transcriptase inhibitors (NNRTI). Among the 464 TPs considered, 331 (71.33%) were distributed among 15 prevalent TPs. The least expensive TP (euro9.95/day; time of costing 1 January 2001-30 April 2002) comprised two drugs (stavudine and lamivudine) and showed a cost differential of +euro16.74 (+62.70%) compared with the most expensive one (zidovudine, lamivudine, lopinavir and ritonavir). The most used TP (zidovudine, lamivudine and nevirapine) covered 61 cases (13.1%) with a daily cost of euro19.61 (time of costing 1 January 2001-30 April 2002).

CONCLUSIONS

This study demonstrated that, starting with decisions that take into account the efficacy of the therapy and the compliance of the patients, and choosing ethical protocols agreed upon with the patients, it is possible to reduce the costs of the TPs. Of the 464 TPs examined, NNRTIs were used in 46.7% of the cases and a PI in 39.6% (16.1% of the latter drug group was boosted with ritonavir). Only 7% of TPs used two drugs (NRTIs). The two less expensive TPs comprised two drugs only (NRTIs). Among the three-drug TPs with a lower cost, the drug pattern was two NRTIs and one NNRTI. The remaining TPs included a PI as a third drug and demonstrated a cost increase greater than 50% with respect to the less expensive treatment.

Location, race, and hospital care for AIDS patients: an analysis of 10 states

This study is the first statewide comparison of hospital utilization and inpatient mortality rates for people with acquired immune deficiency syndrome (AIDS). Data from 120,772 hospital discharge abstracts for all AIDS-related admissions in 10 states (California, Colorado, Florida, Iowa, Kansas, Maryland, New Jersey, New York, Pennsylvania, and South Carolina) in 1996 were combined with data on the number and the racial and ethnic characteristics of all people living with AIDS (PLWAs) in each state. These data were used to derive population-based estimates of the use of hospital services per PLWA and of inpatient mortality rates in each state. Multivariate analyses examined sources of variation in inpatient length of stay and inpatient mortality. The primary finding of this study is that hospital utilization rates and inpatient mortality rates for people with AIDS vary substantially across states and among racial and ethnic groups within states even after adjusting for severity of illness. Blacks and Hispanics had longer hospital stays and were more likely to die in the hospital than whites. State-level policies, such as home and community-based waiver programs and enhanced HIV reimbursement rates, significantly affected hospital use.

Health and federal budgetary effects of increasing access to antiretroviral medications for HIV by expanding Medicaid

OBJECTIVES. This study modeled the health and federal fiscal effects of expanding Medicaid for HIV-infected people to improve access to highly active antiretroviral therapy.

METHODS

A disease state model of the US HIV epidemic, with and without Medicaid expansion, was used. Eligibility required a CD4 cell count less than 500/mm3 or viral load greater than 10,000, absent or inadequate medication insurance, and annual income less than $10,000. Two benefits were modeled, "full" and "limited" (medications, outpatient care). Federal spending for Medicaid, Medicare, AIDS Drug Assistance Program, Supplemental Security Income, and Social Security Disability Insurance were assessed.

RESULTS

An estimated 38,000 individuals would enroll in a Medicaid HIV expansion. Over 5 years, expansion would prevent an estimated 13,000 AIDS diagnoses and 2600 deaths and add 5,816 years of life. Net federal costs for all programs are $739 million (full benefits) and $480 million (limited benefits); for Medicaid alone, the costs are $1.43 and $1.17 billion, respectively. Results were sensitive to awareness of serostatus, highly active antiretroviral therapy cost, and participation rate. Strategies for federal cost neutrality include Medicaid HIV drug price reductions as low as 9% and private insurance buy-ins.

CONCLUSIONS

Expansion of the Medicaid eligibility to increase access to antiretroviral therapy would have substantial health benefits at affordable costs.

Improving the fit of bivariate smoothing splines when estimating longitudinal immunological and virological markers in HIV patients with individual antiretroviral treatment strategies

CD4+ lymphocyte count and HIV RNA plasma viral load are longitudinally monitored in patients with HIV infection. Because data collection intervals may be unequally spaced and these markers experience high within-patient variability, they may be smoothed before use in subsequent models. Estimation strategies must be able to accommodate the drastic changes in viral load which may occur when an individual's treatment strategy is updated. Because these treatment changes are not regimented, these dynamics cannot be modelled using standard methods. We propose univariate and bivariate cubic smoothing splines to fit CD4+ count and viral load over time. The method is developed using state space equations, and the Kalman filter is used to calculate the log-likelihood. Non-linear optimization is used to obtain the maximum likelihood estimates. A modification of the Kalman filter allows non-informative or diffuse priors at the initial observation. Since treatment changes are expected to alter the shape of the curve, we further extend the Kalman filter to permit greater flexibility in the smoothing spline at these time points. The method produces smoothed estimates of the viral load and CD4+ count curves over time.

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.

The impact of state policy on the costs of HIV infection

There is substantial variation in the generosity of public assistance programs that affect HIV+ patients, and these differences should affect the economic outcomes associated with HIV infection. This article uses data from a nationally representative sample of HIV+ patients to assess how differences across states in Medicaid and AIDS Drug Assistance Programs (ADAP) affect costs and labor market outcomes for HIV+ patients in care in that state. Making ADAP programs more generous in terms of drug coverage would reduce per patient total monthly costs, mainly through a reduction in hospitalization costs. In contrast, expanding ADAP eligibility by increasing the income threshold would increase the total cost of care. Expanding eligibility for Medicaid through the medically needy program would increase per patient total costs, but full-time employment would increase and so would monthly earnings. The authors conclude that more generous state policies toward HIV+ patients--especially those designed to provide access to efficacious treatment--could improve the economic outcomes associated with HIV.

The impact of new antiretroic therapeutic schemes on the cost for AIDS treatment in Greece

The paper attempts to evaluate the clinical and economic benefits between the administration of the dual and triple antiretroic schemes for the treatment of the HIV disease. Clinical and economic data are derived from patients hospitalized in 1996 and 1997 at the University Department of Dermatology and Venereology of Andreas Sygros Hospital. Methodology is based on the comparison of patients' nosological profile and direct annual cost before and after the administration of the triple treatment. The results of the study present that the triple combination therapy yields superior health outcomes, (decrease in the days of hospitalization and in the opportunistic disease events as well as fewer deaths and loss of production). Cost comparison presents a small decrease in the annual patient's cost, where all cost components are diminished, except the medication cost. A substitution of hospital care by drug therapy is revealed and a great change is taken place in the composition of the drugs' cost. Patient cost for antiretroic drugs has more than doubled from 1996 to 1997.

The changing economics of HIV care

New advances in human immunodeficiency virus (HIV) monitoring and therapeutics have led to dramatic changes in the course of HIV disease. We evaluated our closed clinic of 425 HIV patients over the period 1995-1998 to determine the cost effectiveness of these changes in care. We found that the costs of antiretroviral therapy tripled over the period of observation, but that these increases were largely offset by major declines in inpatient and home health expenditures. In addition, we found that annual mortality among our HIV patients had declined by 90%. We calculated that the cost per life-year gained is about $17,500, which compares favorably with medical expenditures for renal dialysis or advanced cardiac disease.

Highly active antiretroviral therapy: pharmacoeconomic issues in the management of HIV infection

The advent of highly active antiretroviral therapy (HAART), including protease inhibitors and/or non-nucleoside reverse transcriptase inhibitors, for the treatment of HIV infection has led to a dramatic decline of morbidity and mortality. The acquisition costs of HAART are substantial. However, these costs are partially offset by reduced inpatient care for opportunistic infections and other AIDS-related diseases. Furthermore, job productivity in patients infected with HIV is increased under HAART. In developed countries with a low unemployment rate, the discounted value of savings caused by increased productivity in earlier years exceeds the discounted value of later increases in costs resulting from morbidity. Therefore, HAART represents a very efficient treatment strategy that leads to overall cost savings when taking a societal perspective.

Cost effectiveness of expanded antenatal HIV testing in London

BACKGROUND

Recently the Department of Health announced the introduction in England of voluntary universal HIV screening in early pregnancy to prevent vertical transmission. New data have shown the importance of HIV infection in infants born to mothers who were HIV-negative in early pregnancy and who acquired HIV later in pregnancy or during lactation. This requires consideration of repeat testing in late pregnancy and testing of partners of pregnant women (expanded antenatal HIV testing).

OBJECTIVE

To estimate cost effectiveness of expanded antenatal HIV testing in London (England) within the framework of universal voluntary HIV screening in early pregnancy.

DESIGN

Incremental cost-effectiveness analysis.

METHODS

Cost estimates of service provision for HIV-positive children and adults by stage of HIV infection were combined with estimates of health benefits for infants and parents and with costs of counselling and testing (testing costs). In a pharmacoeconomic model cost effectiveness was estimated for expanded antenatal HIV testing in London for universal and selective strategies.

RESULTS

Testing costs in the plausible range of pounds sterling 4 to pounds sterling 40 translate into favourable incremental cost-effectiveness estimates for expanded antenatal HIV testing in London which is already at low numbers of vertical transmissions averted per 100000 pregnant women who test HIV-negative in early pregnancy. Favourable cost effectiveness for universal expanded testing would require testing costs in the lower range, whereas selective expanded testing may produce favourable cost effectiveness at testing costs close to pounds sterling 40.

CONCLUSION

Based on pharmaco-economic considerations, the authors believe that implementation of expanded HIV testing in London should be considered.

Saquinavir soft-gel capsule: an updated review of its use in the management of HIV infection

Saquinavir is a potent and highly selective HIV protease inhibitor. Initially formulated as a hard-gel capsule (HGC), saquinavir was the first protease inhibitor available commercially for the treatment of patients with HIV infection. The limited oral bioavailability of saquinavir HGC has been improved significantly with the introduction of a soft-gel capsule (SGC) formulation. Saquinavir SGC displays greater than dose-proportional pharmacokinetics and mean area under the plasma concentration-time curve (AUC) values are 8- to 10-fold higher with saquinavir SGC 1200 mg 3 times daily than with the HGC formulation 600 mg 3 times daily, the recommended dosages of the 2 formulations. In combination with other protease inhibitors (particularly "low dose" ritonavir), the oral bioavailability of saquinavir (as either the HGC or SGC formulation) is markedly increased, allowing for reduced dosing frequency and/or dosage. The efficacy and tolerability of once- or twice-daily saquinavir SGC/"low dose" ritonavir combinations are currently being evaluated in patients with HIV infection. Data (up to 48 weeks) from noncomparative and comparative clinical trials evaluating saquinavir SGC-containing combination regimens in adult patients with HIV infection, support and strengthen the clinical efficacy profile of the drug that was demonstrated in initial trials. In antiretroviral therapy-naive and -experienced patients, saquinavir SGC combined with > or =2 nucleoside reverse transcriptase inhibitors (NRTIs), or nelfinavir, or nelfinavir plus 2 NRTIs or nonnucleoside reverse transcriptase inhibitors (NNRTIs), markedly improved immunological and virological surrogate markers (increased mean CD4+ cell counts and decreased mean plasma HIV RNA levels) of HIV infection. Saquinavir SGC demonstrated a trend to greater antiviral efficacy (measured by improvements in surrogate markers) than the HGC formulation (not statistically significant); a significantly greater proportion of patients treated with saquinavir SGC had plasma HIV RNA levels <400 copies/ml than patients receiving the HGC formulation. In the first direct comparison of 2 protease inhibitors, saquinavir SGC plus 2 NRTIs demonstrated similar antiviral efficacy to indinavir plus 2 NRTIs in patients with HIV infection (almost all of whom were antiretroviral therapy-naive); at 24 weeks, a significantly greater increase in CD4+ cell count from baseline was obtained in the saquinavir SGC group compared with the indinavir group, although this difference was not apparent at week 32. Triple therapy with saquinavir SGC plus 2 NRTIs was as effective as nelfinavir-containing triple therapy, or quadruple therapy (saquinavir SGC plus 2 NRTIs plus nelfinavir) in markedly suppressing HIV RNA levels in antiretroviral therapy-experienced or -naive patients. Saquinavir SGC is generally well tolerated. Gastrointestinal disturbances (generally nausea, diarrhoea, abdominal pain, vomiting and dyspepsia of moderate or greater intensity) are the most common adverse events associated with saquinavir SGC-containing therapy. In comparative trials, saquinavir SGC-containing therapy was as well tolerated as indinavir- and nelfinavir-containing therapy; although there were no statistical differences between treatment groups, the incidence of diarrhoea was lower in patients receiving saquinavir SGC compared with nelfinavir, saquinavir SGC plus nelfinavir (all combined with 2 NRTIs) or saquinavir SGC plus nelfinavir without additional therapy. Compared with the HGC formulation, saquinavir SGC appears to be associated with a higher overall incidence of adverse events.

CONCLUSIONS

Clinical trial data have shown that as part of triple or quadruple combination therapy, saquinavir SGC is an effective and generally well tolerated protease inhibitor in antiretroviral therapy-naive or -experienced patients with HIV infection. (ABSTRACT TRUNCATED)

Healthcare Economics in HIV

In an era of cost-consciousness in the delivery of medical care, the economics of healthcare delivery for HIV-infected persons has been an area of active interest. Interested parties include the payors of HIV care, particularly public insurers, who are paying for an increasing amount of the overall cost of HIV care in the US; providers of care, many of whom are finding it increasingly difficult to provide HIV care in a capitated market; and those persons who are HIV-infected and increasingly caught in the economic turmoil of the HIV healthcare marketplace. This paper will review the literature published over the past year regarding the economics of healthcare for HIV in the US.

Meeting the NICE requirements: a Markov model approach

The National Institute of Clinical Excellence (NICE) was established in the United Kingdom in April 1999 to issue guidance for the National Health Service (NHS) on the use of selective new health care interventions. This article describes the NICE requirements for both incidence-based cost-effectiveness analyses and prevalence-based estimates of the aggregate NHS impact of the new drug. The article demonstrates how both of these requirements can be met using Markov modeling techniques. A Markov model for a hypothetical new treatment for HIV infection is used as an illustration of how to generate the estimates that are required by NICE. The article concludes with a discussion of the difficulties of obtaining data of sufficient quality to include in the Markov model to ensure that the submission meets all the NICE requirements and is credible to the NICE advisory board.

Modeling the use of triple combination therapy in five countries: nevirapine, Zidovudine, and Didanosine

OBJECTIVE

In this study, we modify previously published models to estimate the short- and long-term consequences of nevirapine triple combination therapy use in five developed countries. Current pharmacoeconomic practice requires the de novo model development for each new therapy comparison. This approach is lengthy and costly, and it may yield models with very different structures. Standardized, detailed disclosure of model assumptions and parameters makes it possible to recycle published models with minor structural modifications to examine the efficiency of therapies based on new trial data.

METHODS

Two well-publicized models of HIV therapy are modified to fit new trial data comparing double and triple combination therapy with nevirapine; model parameters are adjusted to represent clinical practice and cost structure in five countries. A short-term model uses trial data from advanced-stage patients to estimate first-year costs and consequences. A long-term model uses data from antiretroviral-naïve patients to estimate long-term cost-effectiveness.

RESULTS

During the first year, for each 100 individuals treated with nevirapine triple combination therapy, 2.7 deaths and 30.8-31.4 opportunistic disease events would be averted compared to employing dual therapy. Additionally, 61% to 142% of the first-year costs of nevirapine therapy would be offset by other medical care costs savings [FF19,749, DM3,778, 3334 (x1000) lire, 293 (x1000) ptas, and US $3,569]. Compared to dual combination therapy, nevirapine triple combination therapy is predicted to yield incremental cost-effectiveness ratios (discounted at 3%) of FF101,057, DM30,709, 28,066 (x1000) lire, 1294 (x1000) ptas, and US $14,338.

CONCLUSION

Published, well-constructed, and documented cost-effectiveness models can be reused to estimate the economic impact of therapies for HIV disease. Such models can also be used to provide insight into the factors that affect efficiency across countries. Our use of clinical trial data on nevirapine, together with published HIV economic models, provides support for the hypothesis that nevirapine is cost-effective under the cost structures of five developed countries.

Impact of zidovudine-based triple combination therapy on an AIDS drug assistance program

A static deterministic model was used to estimate the effect of the shift to a triple combination therapeutic standard on the annual AIDS Drug Assistance Program (ADAP) budget, total medical care expenditures, and population health outcomes for New York (NY) state ADAP enrollees. The model used opportunistic disease incidence data from the Multicenter AIDS Cohort Study (MACS) and other studies. Costs of treating opportunistic infections (OIs) and other HIV complications with each type of therapy were derived from treatment algorithms and standard unit costs. CD4+ cell counts were used as an index of need for OI prophylaxis and for determining OI incidence. Treatment with zidovudine-based combination therapy has been shown to increase CD4+ cell counts and reduce OI incidence. The model estimated that a change from monotherapy to triple therapy would have increased NY ADAP budget expenditures per enrollee by 115%. However, total medical system costs per ADAP enrollee (including ADAP costs) would decrease by 0.4% in the base case as a result of reduction in OIs and other HIV sequelae and associated costs. Results are sensitive to the assumed percentage of people taking combination therapy as well as to the assumptions made about the impact of the combination therapy on CD4+ cell count. Total ADAP budget impacts will depend on the growth in ADAP enrollment as a result of the availability of more effective therapies. In conclusion, this model demonstrates how access to newer, more effective HIV drug treatments can reduce the costs of treating OIs and provide major health benefits for ADAP enrollees.

Cost effectiveness of combination HIV therapy: 3 years later

Since 1997, expert panel guidelines for HIV care have recommended the use of combination antiretroviral therapy with at least 3 antiretroviral drugs. Several studies have examined the cost effectiveness of 3-drug combination antiretroviral regimens for the treatment of HIV infection. Analyses comparing a 3-drug protease inhibitor-containing regimen with a 1- or 2-drug non-nucleoside reverse transcriptase inhibitor regimen have consistently yielded incremental direct cost estimates ranging from $US10,000 to just over $US13,000 per year of life saved. In Western societies, such an incremental cost per year of life saved compares favourably with chronic therapy for other diseases and argues for the adoption of these drugs by payors and policy makers. The reason for this favourable cost-effectiveness ratio appears to be the decrease in opportunistic complications and hospitalisation associated with the effective use of combination antiretroviral therapy. Whether this initial benefit will be maintained is not yet known. Other comorbid illnesses such as hepatitis C or renal failure may subsequently increase the cost of HIV care, and some analyses suggest that resistance may develop to these drugs over the long term. In addition, studies are needed to assess the cost effectiveness of these therapies in developing countries where the expense of these drugs appears to put them out of reach. The collection and analysis of economic data will continue to be needed as newer HIV therapies become available and the HIV healthcare environment evolves. Quantifying medical care costs and calculating cost effectiveness involve assessing a moving target. Economic analyses of HIV infection must evolve in tandem with therapeutic changes to continue to be relevant to policy makers, payors of care, and those who provide and receive HIV care.

Immunologic and viral markers of HIV-1 disease progression: implications for dentistry

BACKGROUND

Current medical care for patients infected with the human immunodeficiency virus type 1, or HIV-1, involves monitoring laboratory assays for CD4+ lymphocyte cell count and plasma viral load.

TYPES OF STUDIES REVIEWED

The authors reviewed recent medical and dental studies that contribute to our current understanding of these immunologic and viral markers and their relevance to systemic and oral health.

RESULTS

Dramatic reduction in plasma viral load resulting from more potent antiretroviral drug combinations is the goal of medical management for HIV. These protease inhibitor-containing regimens, although complex, expensive and associated with substantial side effects, have decreased the morbidity and mortality associated with HIV in the United States. Although reduction in viral load can result in increases in CD4+ counts, which restores some level of immune competence, a cure for AIDS has not yet been found.

CLINICAL IMPLICATIONS

Patients with low CD4+ cell counts (and often high viral loads) are more likely to develop destructive periodontal infections and other oral manifestations of HIV. Partial recovery of the immune system after viral load reduction may affect both the prognosis and oral disease experience of these patients.

Cost effectiveness of highly active antiretroviral therapy in HIV-infected patients. Swiss HIV Cohort Study

BACKGROUND

Highly active antiretroviral therapy (HAART) has become the most important strategy for treating HIV infection in developed countries; however, access to HAART might vary under different funding policies. The Swiss health care system provides unrestricted access to HAART for all patients who need these newer combination therapies. This study investigated the impact of this funding policy on the society and health care system.

METHODS

A cost-effectiveness analysis with natural history data and productivity estimates was based on the Swiss HIV Cohort Study. A random sample of patient charts was used to estimate health care costs. In addition to a base-case scenario, a pessimistic and an optimistic scenario of natural disease history was developed. Costs were expressed in 1997 Swiss francs (100 CHF correspond to about US$67) and effects as projected years of life gained.

RESULTS

In the analysis limited to health care costs, on the basis of projected survival in each scenario, the cost-effectiveness ratio was 33,000 CHF (base case), 14,000 CHF (optimistic), and 45,000 CHF (pessimistic) per year of life gained. When changes in productivity were included, cost savings occurred in the base-case and optimistic scenarios. The cost-effectiveness ratio was 11,000 CHF per year of life gained in the pessimistic scenario.

CONCLUSIONS

HAART increases expected survival and health care costs. However, when productivity gains are included, society will probably save costs or pay a low price for substantial health benefits. The study provides strong arguments, from a societal perspective, to continue the current policy of providing unrestricted access to HAART in Switzerland. The presented results also suggest that this policy could be of interest for other developed countries. Decision makers in developed countries where access to HAART is limited should re-evaluate their policy for the benefit of the society at large.

Modeling the long-term outcomes and costs of HIV antiretroviral therapy using HIV RNA levels: application to a clinical trial

A model was developed to gain insight into the potential clinical and economic impact of antiretroviral therapy for HIV-infected patients. Observed HIV RNA levels and CD4 cell counts are used in the model to estimate the probability that an individual progresses from asymptomatic infection to the first AIDS-defining illness and death and to estimate the total net cost of care and long-term cost-effectiveness of antiretroviral therapy. The model was applied to patients in a clinical trial (Merck protocol 035) that compared the surrogate marker response to triple therapy with indinavir (IDV; 800 mg every 8 hr) plus zidovudine (ZDV; 200 mg every 8 hr) plus lamivudine (3TC; 150 mg twice a day) to double therapy with ZDV+3TC. The model projected that for an individual without AIDS who received triple therapy the progression to AIDS and death would be delayed more than for a patient who received double therapy with ZDV+3TC if no other treatment options were offered. Because of this delay in disease progression, the total discounted cost over the initial 5-year period was projected to be $5100 lower for patients who received triple therapy compared with double therapy if suppression with triple therapy lasts up to 3 years. If suppression with triple therapy lasts up to 5 years, costs were projected to be higher with the triple combination, but 81% of the cost is offset by lower disease costs as a result of fewer patients progressing to AIDS. Over 20 years, total discounted cost was projected to be higher for the triple-therapy regimen primarily because of a longer estimated survival time. At 20 years, the incremental cost per life-year gained by adding IDV to a ZDV+3TC regimen was estimated at $13,229, which is well within the range of other widely accepted medical interventions.

A risk-benefit assessment of HIV protease inhibitors

The use of triple regimens, often called highly active antiretroviral therapy (HAART), generally involving 2 nucleoside analogues and an HIV protease inhibitor, have been endorsed as the standard of care for persons with HIV initiating therapy by a number of sets of international guidelines. The widespread availability of protease inhibitor-containing regimens has been associated with a dramatic drop in the incidence of new AIDS events and mortality throughout the developed world. Use of HAART regimens, particularly in treatment-naïve individuals, is also associated with dramatic reductions in HIV RNA load, rises in CD4+ cell numbers and improvements in some aspects of immune function. However, protease inhibitor therapy is associated with a range of adverse effects, which varies between agents, and regimens frequently involve inconvenient administration schedules and disruption to patient's lives. Thus, the undoubted benefits of antiretroviral therapy come at some cost in terms of both physical and psychological morbidity to the recipient. In assessing an individual for therapy, consideration of the risk of disease events and the benefit of therapy in reducing or preventing these events must be weighed against the potential of therapy to cause morbidity. Using these criteria, we suggest that an individual with a 3 year risk of disease progression of less than 10% (based on CD4+ cell count and HIV RNA load) is more likely to a experience a morbidity if treated with HAART than if left untreated and monitored. For individuals with higher risks of HIV progression the risk versus benefit of initiating therapy may, in many cases, still be in favour of no therapy and continued observation. This will vary depending on the individuals risks (such as family and past medical history) and on the choice of agents in the regimen, some regimens having greater risks than others.

Implicit valuation of a blood-exclusion decision

This paper presents an implicit valuation of Israel's decision to exclude blood donations from Ethiopian immigrants. The approach adopts assumptions that deliberately overstate the public health effectiveness of this policy, for if such an analysis fails to justify exclusion on public health grounds, nothing will. Building on a recent (over)estimate of the number of infectious donations prevented by the ban, the analysis considers the cost of HIV-infectious donations entering the blood supply, the benefits of healthy donations, and the cost of needlessly screening blood that will be discarded without regard to the test result. The analysis also highlights the social costs of excluding donors on the basis of ethnicity. The possibility of downstream HIV transmission from transfusion recipients infected from contaminated blood is also considered. All such calculations are made in a manner that deliberately favors the exclusion decision. In spite of such a one-sided analysis, the author concludes that the exclusion policy is not justifiable on cost-benefit grounds if the social costs of exclusion exceed $218,000 per year, or $3.63 per Ethiopian immigrant annually.

Protease inhibitor-based therapy is associated with decreased HIV-related health care costs in men treated at a Veterans Administration hospital

BACKGROUND

Protease inhibitor (PI) therapy for HIV infection is associated with decreased rates of opportunistic infections and death. Statistical models predict that decreased complications will be associated with decreased hospitalization costs. A recent report suggested that the decrease in the HIV hospitalization costs were offset by increases in demand for outpatient services. We performed a study of hospital use and HIV-associated health care costs in our center to determine the following: whether PI therapy is associated with decreased inpatient use; whether PI therapy is associated with decreased outpatient use and costs; whether decreased HIV health care costs are associated with increased use of nucleoside analogues.

METHODS

The Dallas Veteran Affairs Medical Center provides comprehensive inpatient and outpatient HIV care and thus can evaluate the relation between inpatient and outpatient costs. The mean monthly number of hospital days, Infectious Diseases clinic visits, emergency department visits, other outpatient clinic visits, inpatient costs, outpatient costs, and PI costs were determined from January 1, 1995 through July 31, 1997. This time period was then divided into three intervals. Comparisons of PI use and HIV-related health care costs were during the three intervals was performed using analysis of variance (ANOVA). Significant differences between the baseline characteristics were further analyzed through multiple linear regression.

RESULTS

A decrease in hospital days, and all outpatient visits including emergency visits, and HIV clinic visits was determined. No difference was found in the rate of use of other outpatient services. The per patient costs of HIV care decreased from a monthly average of $1905 U.S. in the first interval to $1122 U.S. in the last interval (p < .01). Linear regression demonstrated an inverse relation between PI use and total HIV costs (B=-0.67, p=.00, adjusted R2=0.52) but no relation between nucleoside use, stage of disease or financial class.

CONCLUSIONS

PI therapy is associated with decreased hospital days and use of outpatient services. Total patient costs decreased, but a concomitant rise in outpatient costs took place. This increase was primarily a result of increased costs of acquiring PI. Increases in the number of nucleoside agents prescribed were not associated with decreased costs.

Prevalence-based economic evaluation

OBJECTIVE

Researchers have often stated that economic evaluations of new drugs have rarely been used to inform healthcare decisions, despite the large volume of published studies. In this paper, a new categorization for economic evaluations of new drugs is proposed: incidence-based and prevalence-based. This categorization is designed to increase the likelihood that decision-makers are given more complete and usable economic information about new treatments.

RESULTS

Incidence-based evaluations (such as cost-effectiveness analysis) focus on the impact of a new treatment on a health condition from onset until cure or death. Prevalence-based evaluations focus on the impact of a new treatment on a health condition during a 1-year period. An incidence-based evaluation may focus either on a representative individual or on a specific disease cohort. A prevalence-based evaluation generally focuses on a specific population. Incidence-based evaluations measure the value of the new treatment compared to alternative treatments for the same health conditions and compared to commonly used treatments for other health conditions. Prevalence-based evaluations measure the impact of introducing the new treatment on annual healthcare budgets and population health.

CONCLUSION

Both types of evaluation provide important information when a new treatment is introduced to a population.

Predictors of HIV infection among newly sentenced male prisoners

The prevalence of individuals with or at risk for HIV infection in prisons and jails is severalfold higher than age-adjusted rates in surrounding communities. This HIV serosurvey of 975 newly sentenced male prisoners employed a new methodology that anonymously linked individual information to HIV serologic data. The HIV prevalence was 6.1%; multivariate regression analysis indicated injection drug use (OR = 18.9), black race (OR = 5.5), Hispanic ethnicity (OR = 3.4), psychiatric illness (OR = 3.1) and a history of having had a sexually transmitted disease (OR = 2.2) were independent predictors of HIV infection. Laboratory markers such as hypoalbuminemia, an elevated aspartate aminotransferase (AST) level, leukopenia, anemia, and thrombocytopenia suggest increased risk for HIV among prisoners, particularly in settings where HIV testing resources are scarce. This study, unlike those reported in other geographic regions, indicated that the majority (71%) of HIV-seropositive persons self-reported their HIV status. This finding may suggest that HIV-infected individuals will self-report their status if HIV care is comprehensive and consistent. The large number of HIV-infected individuals within prisons makes prisons important sites for the introduction of comprehensive HIV-related care. This is particularly relevant in that development of new guidelines issued for the management of HIV infection in which potent combination antiretroviral therapy has been demonstrated to decrease morbidity and mortality. The high prevalence of HIV-seronegative inmates with self-reported high-risk behaviors also suggests the importance of prisons as sites for the introduction of appropriate risk-reduction interventions.

A Monte Carlo simulation of advanced HIV disease: application to prevention of CMV infection

BACKGROUND

Disagreement exists among decision makers regarding the allocation of limited HIV patient care resources and, specifically, the comparative value of preventing opportunistic infections in late-stage disease.

METHODS

A Monte Carlo simulation framework was used to evaluate a state-transition model of the natural history of HIV illness in patients with CD4 counts below 300/mm3 and to project the costs and consequences of alternative strategies for preventing AIDS-related complications. The authors describe the model and demonstrate how it may be employed to assess the cost-effectiveness of oral ganciclovir for prevention of cytomegalovirus (CMV) infection.

RESULTS

Ganciclovir prophylaxis confers an estimated additional 0.7 quality-adjusted month of life at a net cost of $10,700, implying an incremental cost-effectiveness ratio of roughly $173,000 per quality-adjusted life year gained. Sensitivity analysis reveals that this baseline result is stable over a wide range of input data estimates, including quality of life and drug efficacy, but it is sensitive to CMV incidence and drug price assumptions.

CONCLUSIONS

The Monte Carlo simulation framework offers decision makers a powerful and flexible tool for evaluating choices in the realm of chronic disease patient care. The authors have used it to assess HIV-related treatment options and continue to refine it to reflect advances in defining the pathogenesis and treatment of AIDS. Compared with alternative interventions, CMV prophylaxis does not appear to be a cost-effective use of scarce HIV clinical care funds. However, targeted prevention in patients identified to be at higher risk for CMV-related disease may warrant consideration.

Evaluating the cost of medications for ambulatory HIV-infected persons in association with landmark changes in antiretroviral therapy

Costs of medications for ambulatory HIV-infected people increase as knowledge of antiretroviral therapy and therapy for opportunistic infection grows. We evaluated the evolution of drug costs for HIV-infected persons who attend a university clinic in Baltimore, Maryland. Cross-sectional abstracts of a cohort of patients for four periods, corresponding to landmark changes in therapy, who attended the clinic between June 1995 and September 1996 were obtained. Monthly medication costs for all patients were calculated. Mean costs increased significantly (p < .01) from period 1 ($447 U.S.) to period 4 ($1048 U.S.). Multivariate analysis only revealed higher costs for patients with a CD4+ count <200 cells/mm3 (p < .001). The proportion of costs attributable to antiretroviral therapy increased from 34% in period 1 to 53% in period 4. Combination therapy increased >10-fold, from 8% in period 1 to 94% in period 4. Protease inhibitor use also increased significantly, from 4% in period 2 to 53% in period 4. We quantified the increase in costs of medications from mid-1995 to late 1996. Increases in costs appear to be the result of increasing complexity of drug regimens, particularly antiretroviral therapy in combinations.

Cost-utility analysis of prophylactic treatment with oral ganciclovir for cytomegalovirus retinitis

OBJECTIVE

Cytomegalovirus (CMV) retinitis is a relatively common opportunistic infection in late-stage HIV disease, causing significant morbidity and mortality. Prophylactic use of oral ganciclovir has recently been shown to decrease the incidence of CMV retinitis but is relatively expensive and may not be very well tolerated by many patients. We performed a decision analysis to assess the cost-effectiveness of prophylactic oral ganciclovir therapy.

METHODS

A decision analysis using a Markov approach compared absence of prophylaxis and prophylaxis with oral ganciclovir. Estimates of effectiveness of prophylaxis and costs of illness were obtained from published literature. Drug costs were based on national average wholesale prices. All health care costs were based on 1996 U.S. dollars. Sensitivity analyses were done over ranges of estimates of cost and effectiveness.

RESULTS

Using our baseline estimates of cost and effectiveness, use of oral ganciclovir prophylaxis in patients with CD4 counts <50 cells/mm3 would be associated with average lifetime health care costs of $104,746, compared with $90,985 for no prophylaxis. Using oral ganciclovir, the average quality-adjusted life-years (QALYs) would be 2.05, and the CMV retinitis-free life-years would be 1.64, compared with 1.87 and 1.27, respectively, for no prophylaxis. The incremental cost-utility of oral ganciclovir is $76,676 per year of life saved and $37,542 per year of additional CMV retinitis-free life. Oral ganciclovir would become more cost-effective relative to no prophylaxis if the probability of CMV retinitis while taking oral ganciclovir declined. Oral ganciclovir would be less cost-effective if the cost of treating CMV retinitis declines, if our estimates of quality of life are low, or if the overall incidence of CMV retinitis declines.

CONCLUSIONS

Oral ganciclovir is a less cost-effective approach than several other interventions used for HIV-disease prophylaxis. It would potentially become cost-effective if it is possible to target oral ganciclovir prophylaxis to patients who are most likely to benefit.