Drug Use and Sexual Risk Behaviours among Female Russian IDUs Who Exchange Sex for Money or Drugs

Countries of the former Soviet Union are experiencing the steepest increases in annual HIV incidence in the world. Over 80% of registered HIV cases in Russia have occurred among intravenous drug users (IDUs), but current conditions set the stage for a heterosexually-transmitted epidemic. IDUs who also trade sex for money or drugs may serve as a conduit, or ‘bridge’ group, through which HIV could make inroads into the general Russian population. The present study examined the prevalence of sex trading among female Russian IDUs, and further examined drug use, sexual behaviour, and perceived vulnerability in this group. Female IDUs ( n=100) in St Petersburg, Russia participated; 37% reported a history of sex trading. This group reported a mean of 49.5 male sexual partners in the previous month and an average of 15.4 unprotected vaginal intercourse acts in the previous 30 days. A significant minority (44%) also reported sharing injection equipment with others. Mathematical models to calculate risk estimates for HIV seroconversion indicated that participants were at significant risk of contracting HIV and infecting sexual partners. Despite significant rates of risk behaviours, most participants perceived themselves to be at little risk of contracting HIV. Effective HIV prevention programmes targeted at this group are urgently needed and are likely to be a cost-effective step in curtailing the spread of HIV In the region.

Perceived Benefits and Barriers Associated with the Female Condom among African-American Adults

This study examined perceived benefits and barriers associated with intentions to use the female condom among a sample of 143 African-American adults in Milwaukee, USA. Participants completed a self-report questionnaire. Aesthetics and contraceptive efficacy predicted women's intentions to use the female condom with a main sex partner. For men, intentions to use the device with a main partner were predicted by beliefs that the female condom is affordable, would prevent STDs, that their partner would not be angry about female condom use, and knowing how to use the device. Interventions to promote this device need to be tailored differently for men and women.

All STDs are not created equal: an analysis of the differential effects of sexual behaviour changes on different STDs

The same sexual behaviours that transmit HIV are implicated in the transmission of certain other STDs, including chlamydia, gonorrhoea, and syphilis. Consequently, it is often assumed that preventive methods that are effective against HIV should be equally effective against other STDs. The purpose of this study was to examine this assumption. We applied a mathematical model of HIV/STD transmission to empirical data from a large HIV prevention intervention that stressed sexual behaviour change. We modelled the effects of two behavioural strategies - reducing the number of sex partners and increasing condom use-on the proportionate change in intervention participants' cumulative risk of acquiring HIV or a highly-infectious STD, such as gonorrhoea. The results of this modelling exercise indicate that decreasing the number of partners is a more effective strategy for reducing STD risk than it is for HIV risk. In contrast, condoms are somewhat more effective at reducing the cumulative transmission risk for HIV than for highly infectious STDs. The protection provided by condoms for multiple acts of intercourse critically depends on the infectiousness of the STD. The results of this study suggest caution in extrapolating from one STD to another, or from one behavioural risk reduction strategy to another.

Influence of a partner's HIV serostatus, use of highly active antiretroviral therapy, and viral load on perceptions of sexual risk behavior in a community sample of men who have sex with men

OBJECTIVE

To assess the perceptions of gay and bisexual men concerning the risk of HIV transmission through various sexual practices with a new sex partner depending on that partner's disclosed HIV status, antiretroviral treatment status, and viral load.

METHODS

Study participants read four different scenarios describing sexual situations with a new partner and rated each scenario for risk of HIV transmission. HIV status and antiretroviral treatment status disclosed by the new sex partner were varied across four scenarios: unknown HIV status; HIV-negative; HIV-positive and not taking highly active antiretroviral therapy (HAART); and HIV-positive and taking HAART with an undetectable viral load.

RESULTS

Study participants were 472 men attending a gay pride festival who reported that they were HIV-negative. Eighty-nine percent of the men were white, and the mean age of the study participants was 35.8 years. Of the four scenarios, sex with an HIV-positive partner not taking HAART was rated as posing the greatest risk. Sex with an HIV-positive partner taking HAART who had an undetectable viral load was not consistently viewed as riskier than sex with an HIV-negative partner or a man with an unknown HIV status.

CONCLUSIONS

The current study provides preliminary evidence for the effect of disclosure of HIV serostatus, use of HAART, and the presence of an undetectable viral load on the perceptions of sexual risk for HIV-negative men. The findings suggest that some gay and bisexual men judge risk based on the perceived HIV status of their sex partners and not on the general assumption that all sex partners entail equal risk, as many prevention campaigns have emphasized.

HIV prevention community planning and communities of color: do resources track the epidemic?

The Centers for Disease Control and Prevention (CDC) funds provided to state, local, and territorial health departments for HIV-prevention activities are prioritized with the substantial involvement of HIV-prevention community planning groups (CPGs). This article examines whether or not these funds (more than $261 million in fiscal year 1998) are allocated in a way that mirrors the HIV/AIDS epidemic in terms of race/ethnicity. AIDS prevalence data were used to reflect disease burden, and were compared to budget data submitted by health departments to the CDC. The budget data report expenditures by race/ethnicity for two major types of activities: (1) health education and risk reduction (more than $104 million); and (2) counseling, testing, referral, and partner notification (more than $91 million). The rank order correlation between funding and AIDS prevalence data for the five specific racial/ethnic categories was .900 (n = 5, p < .05) for health education and risk reduction (HERR) activities, and 1.000 (n = 5, p < .05) for counseling, testing, referral, and partner notification (CTRPN) activities. From 1997 to 1998, the proportion of funds targeted and accounted for by race/ethnicity increased from 79 percent to 88 percent for HERR, and from 71 percent to 84 percent for CTRPN activities. With regard to race/ethnicity, health departments and CPGs appear to be actively targeting and accounting for HIV prevention resources, and we will argue that relatively small changes in counseling and testing resources for African-American and Latino/Latina communities would result in a close match between AIDS prevalence data and devoted resources.

Probabilistic cost-effectiveness analysis of HIV prevention. Comparing a Bayesian approach with traditional deterministic sensitivity analysis

In cost-effectiveness analysis, the incremental cost-effectiveness ratio is used to measure economic efficiency of a new intervention, relative to an existing one. However, costs and effects are seldom known with certainty. Uncertainty arises from two main sources: uncertainty regarding correct values of intervention-related parameters and uncertainty associated with sampling variation. Recently, attention has focused on Bayesian techniques for quantifying uncertainty. We computed the Bayesian-based 95% credible interval estimates of the incremental cost-effectiveness ratio of several related HIV prevention interventions and compared these results with univariate sensitivity analyses. The conclusions were comparable, even though the probabilistic technique provided additional information.

Sexual risk compensation and HIV/STD transmission: empirical evidence and theoretical considerations

This study was conducted to answer the question, "Are sexual risk behaviors subject to compensation?" For example, do people who increase their use of condoms compensate for this reduction in human immunodeficiency virus and sexually transmitted disease (HIV/STD) risk by engaging in more overall acts of intercourse or by having sex with more partners than before? Utilizing the HIV prevention literature, studies in which participants demonstrated sexual risk compensation were identified. A simple HIV/STD transmission model was applied to these data to determine whether compensation produced a net increase in HIV/STD risk, despite positive changes in one or more aspects of sexual behavior. Although a number of studies were found in which there were simultaneous increases in condom use and the overall number of acts of intercourse, in none of these instances was there an overall increase in HIV/STD risk. Moreover, none of these studies reported concomitant increases in the number of sex partners. Extensive modeling exercises also were conducted to determine the theoretical conditions under which compensation would produce a net increase in risk. The results of the modeling exercise indicated that relatively small increases in overall sexual activity could be sufficient to offset risk-reduction gains due to increased condom use in populations in which baseline condom use is very low. In sum, although sexual risk compensation occurs, no empirical evidence was found that this compensation is sufficient to offset reductions in risk due to greater condom use, despite the theoretical plausibility of this scenario.

Using cost-effectiveness league tables to compare interventions to prevent sexual transmission of HIV

Cost-effectiveness information is needed to help public health decision makers choose between competing HIV prevention programs. One way to organize this information is in a 'league table' that lists cost-effectiveness ratios for different interventions and which facilitates comparisons across interventions. Herein we propose a common outcome measure for use in HIV prevention league tables and present a preliminary league table of interventions to reduce sexual transmission of HIV in the US. Fifteen studies encompassing 29 intervention for different population groups are included in the table. Approximately half of the interventions are cost-saving (i.e. save society money, in the long run), and three-quarters are cost-effective by conventional standards. We discuss the utility of such a table for informing the HIV prevention resource allocation process and delineate some of the difficulties associated with the league table approach, especially as applied to HIV prevention cost-effectiveness analysis.

Cost-effectiveness of an HIV prevention intervention for mentally ill adults

Adults with severe mental illness are at high risk for human immunodeficiency virus (HIV) infection and transmission. Small-group interventions that focus on sexual communication, condom use skills, and motivation to practice safer sex have been shown to be effective at helping mentally ill persons reduce their risk for HIV. However, the cost-effectiveness of these interventions has not been established. We evaluated the cost-effectiveness of a 9-session small-group intervention for women with mental illness recruited from community mental health clinics in Milwaukee, Wisconsin. We used standard techniques of cost-utility analysis to determine the cost per quality-adjusted life year (QALY) saved by the intervention. This analysis indicated that the intervention cost $679 per person, and over $136,000 per QALY saved. When the analysis was restricted to the subset of women who reported having engaged in vaginal or anal intercourse in the 3 months prior to the baseline assessment, the cost per QALY saved dropped to approximately $71,000. These estimates suggest that this intervention is marginally cost-effective in comparison with other health promotion interventions, especially if high-risk, sexual-active women are preferentially recruited.

A relative risk-based, disease-specific definition of sexual abstinence failure rates

Sexual abstinence programs have the potential to reduce the incidence of unplanned pregnancies and sexually transmitted diseases (STDs) among adolescents. Effectiveness measures are needed to help researchers assess the impact of sexual abstinence promotion programs on STD and pregnancy rates and to enable comparisons of abstinence effectiveness with other contraception and STD prevention methods. Abstinence "failure rates" have been proposed as one measure of program effectiveness. However, the concept of abstinence failure rates has not been adequately operationalized. The present study examines a novel mathematical framework for estimating abstinence failure rates, both theoretically and empirically. Examples are provided, and the advantages and disadvantages associated with the mathematical model-based approach are discussed.

Economic evaluation of HIV risk reduction intervention in African-American male adolescents

PURPOSE

To evaluate the cost-effectiveness of a cognitive-behavioral HIV risk reduction intervention for African-American male adolescents that has previously been shown to be effective at reducing sexual risk taking.

METHODS

Standard techniques of cost-utility analysis were employed. A societal perspective and a 3% discount rate were used in the main analysis. Program costs were ascertained retrospectively. A mathematical model of HIV transmission was used to translate observed changes in sexual behavior into an estimate of the number of HIV infections the intervention averted. Intervention effects were assumed to last for 1 year. For each infection averted, the corresponding savings in future HIV-related medical care costs and quality-adjusted life years (QALYs) were estimated. The overall net cost per QALY saved (cost-utility ratio) was then calculated. Sensitivity analyses were performed to assess the robustness of the main results.

RESULTS

The cost-utility ratio was approximately $57,000 U.S. per QALY saved when training costs were included, and $41,000 U.S. per QALY saved when they were excluded. The intervention appeared substantially more cost-effective when the analysis was restricted to the subgroup of participants who reported being sexually active at baseline. Assumptions about the prevalence of HIV infection and the duration of intervention effectiveness also greatly affected the cost-utility ratio.

CONCLUSIONS

The HIV prevention intervention was moderately cost-effective in comparison with other health care programs. Selectively implementing the intervention in high-HIV prevalence communities and with sexually active youth can enhance cost-effectiveness.

Consequences of HIV prevention interventions and programs: spectrum, selection, and quality of outcome measures

The outcome measures employed in an HIV prevention intervention study should match the research and policy questions at hand. If the question is 'did the intervention work to prevent HIV infection?', then seroincidence data may be insufficient. However, if the question is 'why did the intervention work?', then more detailed behavioral data are necessary (and sometimes behavior change itself is the real goal of an intervention study). Given the wide range of questions asked by HIV prevention policy makers, funders and researchers, a spectrum of outcome measures is needed across HIV prevention intervention studies. These include measures of behavioral determinants, HIV-related risk behaviors, HIV incidence (and other biologic markers), morbidity, mortality, and cost-effectiveness factors (such as cost per quality-adjusted life year saved). In this paper, we review the range of outcome measures used and needed in these intervention studies. Particular attention is paid to the psychometric properties of self-reported behavior change measures of sexual behavior and substance use. Additional emphasis is placed on the role of cost-effectiveness measures in intervention studies. A general framework is proposed for conceptualizing the array of outcome measure possible for any given HIV prevention intervention study.

Prioritization methods for HIV community planning

Since 1994, community planning groups (CPGs) have played an important role in shaping local HIV prevention efforts. The community planning process requires CPGs to prioritize HIV prevention interventions and unmet needs among at-risk populations. This article describes and compares four prioritization methods: (1) the ranking method, (2) Holtgrave's method, (3) Kaplan's method, and (4) a novel utility-based prioritization method. These methods are compared in terms of effectiveness, efficiency, equity, and political feasibility. The methods described here are meant to assist CPGs in the difficult prioritization task by helping CPG members organize their thoughts in the prioritization process.

Cost-threshold analyses of the National AIDS Demonstration Research HIV prevention interventions

OBJECTIVE

The goal of the multisite National AIDS Demonstration Research (NADR) program was to reduce the sexual and drug injection-related HIV risks of out-of-treatment injection drug users and their sex partners. Previous analyses have established that the NADR interventions were effective at changing participants' risky behaviors. This study was to determine whether the NADR program also was cost-effective.

METHODS

Data from eight NADR study sites were included in the analysis. A mathematical model was used to translate reported sexual and injection-related behavior changes into an estimate of the number of infections prevented by the NADR interventions and then to calculate the corresponding savings in averted HIV/AIDS medical care costs and quality-adjusted years of life, assuming United States values for these parameters. Because cost data were not collected in the original NADR evaluation, the savings in averted medical care costs were compared with the cost of implementing a similar intervention program for injection drug users.

RESULTS

The eight NADR interventions prevented approximately 129 infections among 6629 participants and their partners. Overall, the NADR program would be cost saving (i.e. provide net economic savings) if it cost less than US$2107 per person and would be cost-effective if it cost less than US$10,264 per person. Both of these estimates are considerably larger than the US$273 per person cost of the comparison intervention. There was substantial cross-site variability.

CONCLUSIONS

The results of this analysis strongly suggest that the NADR interventions were cost-saving overall and were, at the very least, cost-effective at all eight sites. In the United States and other developed counties, investments in HIV-prevention interventions such as these have the potential to save substantial economic resources by averting HIV-related medical care expenses among injection drug users.

When is an HIV infection prevented and when is it merely delayed?

HIV prevention programs are typically evaluated using behavioral outcomes. Mathematical models of HIV transmission can be used to translate these behavioral outcomes into estimates of the number of HIV infections averted. Usually, intervention effectiveness is evaluated over a brief assessment period and an infection is considered to be prevented if it does not occur during this period. This approach may overestimate intervention effectiveness if participants continue to engage in risk behaviors. Conversely, this strategy underestimates the true impact of interventions by assuming that behavioral changes persist only until the end of the intervention assessment period. In this article, the authors (a) suggest a simple framework for distinguishing between HIV infections that are truly prevented and those that are merely delayed, (b) illustrate how these outcomes can be estimated, (c) discuss strategies for extrapolating intervention effects beyond the assessment period, and (d) highlight the implications of these findings for HIV prevention decision making.

Cost-effectiveness of an HIV risk reduction intervention for adults with severe mental illness

Small-group HIV prevention interventions that focus on individual behavioural change have been shown to be especially effective in reducing HIV risk among persons with severe mental illness. Because economic resources to fund HIV prevention efforts are limited, health departments, community planning groups and other key decision-makers need reliable information on the cost and cost-effectiveness (not solely on effectiveness) of different HIV prevention interventions. This study used an economic evaluation technique known as cost-utility analysis to assess the cost-effectiveness of three related cognitive-behavioural HIV risk reduction interventions: a single-session, one-on-one intervention; a multi-session small-group intervention; and a multi-session small-group intervention that taught participants to act as safer sex advocates to their peers. For men, all three interventions were cost-effective, but advocacy training was the most cost-effective of the three. For women, only the single-session intervention was cost-effective. The gender differences observed here highlight the importance of focusing on gender issues when delivering HIV prevention interventions to men and women who are severely mentally ill.

Sexually transmitted diseases and the increased risk for HIV transmission: implications for cost-effectiveness analyses of sexually transmitted disease prevention interventions

We estimated the annual number and cost of new HIV infections in the United States attributable to other sexually transmitted diseases (STDs). We used a mathematical model of HIV transmission to estimate the probability that a given STD infection would facilitate HIV transmission from an HIV-infected person to his or her partner and to calculate the number of HIV infections due to these facilitative effects. In 1996, an estimated 5,052 new HIV cases were attributable to the four STDs considered here: chlamydia (3,249 cases), syphilis (1,002 cases), gonorrhea (430 cases), and genital herpes (371 cases). These new HIV cases account for approximately $985 million U.S. in direct HIV treatment costs. The model suggested that syphilis is far more likely than the other STDs (on a per-case basis) to facilitate HIV transmission. This analysis provides a framework for incorporating STD-attributable HIV treatment costs into cost-effectiveness analyses of STD prevention programs.

Hispanic adults' beliefs, attitudes, and intentions regarding the female condom

The present study used the theory of planned behavior (TPB) (Ajzen, 1985) augmented by AIDS knowledge to investigate factors influencing intentions of Hispanic adults to use the female condom. A total of 146 persons (75 women and 71 men; mean age, 27 years) recruited from community-based organizations completed an anonymous survey regarding intentions to use the female condom with their main sex partner. The TPB model had greater predictive utility for women's, than for men's, female condom use intentions. For men, attitudes and norms did not predict female condom use intentions, but greater AIDS knowledge was related to lower intentions to use the female condom, above and beyond the TPB constructs. Perceived behavioral control, operationalized as self-efficacy, significantly increased the predictive utility of the TPB model for women's female condom use intentions but not for men's. Behavior change strategies to increase female condom use are discussed in light of these findings.

Decision-making in HIV prevention community planning: an integrative review

Since 1994, the Centers for Disease Control and Prevention has required that the 65 health department grantees that receive funding for HIV prevention interventions engage in a community planning process to involve affected communities in local prevention decision making; to increase the use of epidemiological data to target HIV prevention resources; and to ensure that the planning process takes into account scientific information on the effectiveness and efficiency of different HIV interventions. Local community planning groups are charged with identifying and prioritizing unmet HIV prevention needs in their communities, as well as prioritizing prevention interventions designed to address these needs. Their recommendations, in turn, form the basis for the local health department's request for HIV prevention funding from the Centers for Disease Control and Prevention. Given the community planning process's central role in the allocation of federal HIV prevention funds, it is critical that sound decision-making procedures inform this process. In this article, we review the basics of the community planning prioritization process and summarize the decision-making experiences of community planning groups across the US. We then describe several priority-setting tools and decision analytic models that have been developed to assist in HIV community planning prioritization and discuss their strengths and weaknesses. Finally, we offer suggestions for improving the decision-analytic basis for HIV prevention community planning.

How HIV treatment advances affect the cost-effectiveness of prevention

OBJECTIVE

The cost-effectiveness of an HIV prevention program depends, in part, on its potential to avert HIV-related medical care costs. Recent advances in antiretroviral therapy have made HIV/AIDS treatment both more effective and more costly, which might make HIV prevention either more or less cost-effective. The objective of the present study was to explicate the relationship between the effectiveness and costs of HIV treatment and the cost-effectiveness of HIV prevention programs.

METHODS

A basic analytic framework was used to compare the cost-effectiveness of HIV prevention interventions with respect to different HIV/AIDS medical care scenarios. Algebra was used to calculate a cost-effectiveness threshold that distinguishes prevention programs that become more cost-effective when therapeutic advances simultaneously increase or decrease the cost and effectiveness of treatment from those that become less cost-effective. Recent estimates of the costs and consequences of combination antiretroviral therapy were used to illustrate the calculation method.

RESULTS

The advent of combination antiretroviral therapies for HIV has increased the cost-effectiveness of some, but not all, HIV prevention interventions.

CONCLUSIONS

Whether a particular prevention program becomes more or less cost-effective as a consequence of advancements in the medical treatment of HIV/AIDS depends upon the specific characteristics of both the program and the therapy.

Incremental cost-effectiveness of two zidovudine regimens to prevent perinatal HIV transmission in the United States

BACKGROUND

Recently concluded clinical trials in Thailand have demonstrated that a short course of zidovudine therapy administered to human immunodeficiency virus-infected women during late pregnancy and labor can substantially reduce the likelihood of perinatal transmission of HIV. This regimen is both less expensive and less effective than the full course of therapy recommended for use in the United States by the U.S. Public Health Service (PHS). The objective of the current study is to estimate the incremental cost-effectiveness of the full-course zidovudine regimen in comparison to the short-course regimen that was tested in Thailand and to determine conditions under which the PHS-recommended regimen produces a net savings in societal resource utilization, relative to the shorter regimen.

METHODS

We used standard methods of incremental cost-effectiveness analysis and derived cost and effectiveness estimates from published studies. The main outcome measure is the incremental cost-effectiveness ratio, which is the additional cost per additional case of perinatal HIV infection averted by the full course of therapy.

RESULTS

Full-course zidovudine therapy costs an additional $21,337 per additional case of HIV infection averted, relative to the shorter regimen; this is much less than the cost of treating a case of pediatric HIV infection.

CONCLUSIONS

Economic and clinical findings both favor full-course zidovudine therapy over short-course therapy to prevent perinatal transmission of HIV in the United States.

Secondary HIV transmission rates in a mixed-gender sample

Information about the sexual behaviour of HIV-infected individuals is needed to predict the course of the sexually transmitted HIV epidemic in the US. The present study provides model-based estimates of the secondary transmission rate (i.e. the number of infections expected among the sex partners of already infected individuals) for a sample of HIV-positive persons in Atlanta. A mathematical model was used to estimate the secondary transmission rate of HIV infection for a sample of HIV-positive men and women in Atlanta, based on their self-reported sexual behaviour, extrapolated over a 15-year horizon. Separate rates were calculated for different transmission routes, including: from women to men-who-have-sex-with women (MSW) and from men-who-have-sex-with-men (MSM) to other MSM. Sensitivity analyses were conducted to assess the impact of different parametric and modelling assumptions. Restricted to the sub-sample that reported transmission risk behaviours, the mean number of secondary infections was 0.14 for transmission from women to MSW; 0.31 for transmission from MSW to women; and 0.84 for MSM to MSM transmission. Bisexual men were at especially high transmission risk, with 1.59 and 0.54 secondary infections expected among their male and female partners, respectively. The main analysis indicates that, in this sample, each current infection will lead to fewer than one future infection for all groups other than bisexual men, which suggests that the epidemic is contracting in this community, although this analysis cannot rule out the possibility of a growing epidemic among MSM. This method can be used to identify groups at high risk for HIV transmission and thereby to better target HIV prevention resources.

New HIV cases attributable to syphilis in the USA: estimates from a simplified transmission model

OBJECTIVE

Because syphilis can raise the likelihood of HIV transmission and acquisition, syphilis prevention in the USA has the potential benefit of reducing the number of new cases of HIV. We developed a simplified transmission model to estimate the annual number and cost of new, heterosexually-acquired HIV cases in the USA attributable to syphilis.

DESIGN

We estimated the number of heterosexual, HIV serodiscordant partnerships in which syphilis was present in 1996. The model included the probability of transmission of HIV (with and without the presence of syphilis) and other parameters based on data from recent literature. Published direct costs (HIV treatment costs including antiretroviral therapy) and indirect costs (e.g., lost productivity) per case of HIV were used to estimate the annual cost of HIV cases attributable to syphilis. The potential savings in averted HIV costs related to syphilis were used to estimate the potential benefits of a syphilis elimination program.

RESULTS

In 1996, an estimated 1082 new heterosexual cases of HIV in the USA could be attributed to syphilis. These cases represented direct costs of US$ 211 million and indirect costs of US$ 541 million; yielding US$ 752 million in total costs. Over 15 years, a syphilis elimination program could save over US$ 833 million (discounted at 3% annually) in averted direct medical costs of syphilis-related HIV infections.

CONCLUSIONS

If the only benefit of syphilis elimination were to prevent new HIV cases attributable to syphilis, a national syphilis elimination program costing less than US$ 833 million would probably pay for itself.

Economic impact of delaying or preventing AIDS in persons with HIV

OBJECTIVES

To investigate how preventing or delaying the development of acquired immune deficiency syndrome (AIDS) [or other severe conditions related to the human immunodeficiency virus (HIV)] through antiretroviral therapy affects the lifetime cost of HIV/AIDS care, and to compare the cost of therapy with the potential savings in HIV/AIDS-related end-of-life care.

METHODS

The analysis utilized a previously developed economic model of HIV/AIDS-related medical care costs under various disease progression scenarios to compare the costs and benefits of antiretroviral therapy.

RESULTS

The analysis suggests that: (1) recent projections of long-term medical care cost savings due to highly effective protease inhibitor combination therapies are probably illusory; (2) it makes relatively little difference to the overall long-term cost of HIV/AIDS care whether combination antiretroviral therapy completely prevents or just substantially delays progression to AIDS; and (3) although combination therapy is not likely to save economic resources in the long run, it nevertheless can be highly cost effective.

CONCLUSIONS

The health-related benefits of antiretroviral therapy are not free, but appear to be worth the cost.

Implications of HIV treatment advances for behavioral research on AIDS: protease inhibitors and new challenges in HIV secondary prevention

Protease inhibitor combination therapies can reduce HIV viral load, improve immune system functioning, and decrease mortality from AIDS. These medical developments raise a host of critical new issues for behavioral research on HIV/AIDS. This article reviews developments in HIV combination therapy regimens and behavioral factors involved in these regimens and focuses on four key behavioral research areas: (a) the development of interventions to promote treatment adherence, (b) psychological coping with HIV/AIDS in the context of new treatments for the disease, (c) the possible influence of treatment on continued risk behavior, and (d) behavioral research in HIV prevention and care policy areas. Advances in HIV medical care have created important new opportunities for health psychologists to contribute to the well-being of persons with HIV/AIDS.

Reliability and validity of a self-efficacy instrument for protective sexual behaviors

The authors investigated the psychometric properties of a 22-item scale that measured respondents' perceptions of their ability to refuse sexual intercourse, question potential sexual partners, and use condoms. Two hundred twenty-one male and female undergraduates completed an anonymous questionnaire that measured a wide range of constructs. The scale exhibited good internal consistency, and convergent validity was demonstrated for 5 sexual behavior items (number of sexual partners ever and in the past 3 months, condom use in past 3 months, at last intercourse, and in the future). The instrument appeared to be free of social desirability bias and was reliable and valid for assessing college students' self-efficacy for protective sexual behaviors. College healthcare professionals could administer the instrument to help students determine their levels of self-efficacy for engaging in self-protective behaviors and identify domains in which they may need to improve their skills to reduce their risks of acquiring a sexually transmitted disease or having or causing an unplanned pregnancy.

HIV seropositivity rates in outreach-based counseling and testing services: program evaluation

A common assumption is that outreach-based HIV counseling and testing services reach a clientele with a higher HIV seroprevalence than clinic-based counseling and testing. To examine this assumption, we analyzed Wisconsin's anonymous counseling and testing client records for 62,299 contacts (testing episodes) from 1992 to 1995. Bivariate analysis of counseling and testing service setting (outreach-based or clinic-based) and HIV test results suggested that outreach contacts were 23% (odds ratio [OR], 1.23; 95% confidence interval [95% CI], 1.0-1.5) more likely to test HIV-seropositive than clinic-based contacts. Relations between HIV test outcome and variables for client age, race, gender, previous testing history, mode of risk exposure, and region, as well as service setting, were examined by logistic regression. An inverted relation between service setting and seropositivity (OR, 0.65; 95% CI, 0.5-0.8) indicated that, within some subpopulations, outreach contacts were significantly less likely to test HIV-positive than clinic-based contacts. Analysis of interactions among the covariates identified race as a critical codeterminant in the relation between service setting and test outcome. These results support retargeting outreach services to enhance their overall effectiveness. Specific recommendations include the need for aggressive strategies to better "market" HIV counseling and testing to nonwhite populations, and to focus resources more selectively on gay/bisexual men of all races.

Cost-effectiveness of a community-level HIV risk reduction intervention

OBJECTIVES

The authors evaluated the cost-effectiveness of a community-level HIV prevention intervention that used peer leaders to endorse risk reduction among gay men.

METHODS

A mathematical model of HIV transmission was used to translate reported changes in sexual behavior into an estimate of the number of HIV infections averted.

RESULTS

The intervention cost $17,150, or about $65,000 per infection averted, and was therefore cost-saving, even under very conservative modeling assumptions.

CONCLUSIONS

For this intervention, the cost of HIV prevention was more than offset by savings in averted future medical care costs. Community-level interventions to prevent HIV transmission that use existing social networks can be highly cost-effective.

Cost and cost-effectiveness of increasing access to sterile syringes and needles as an HIV prevention intervention in the United States

We determined the cost of increasing access of injection drug users (IDUs) to sterile syringes and needles as an HIV prevention intervention in the United States and the cost per HIV infection averted by such a program. We considered a hypothetical cohort of 1 million active IDUs in the United States. Standard methods were used to estimate the cost and cost-effectiveness of policies to increase access to sterile syringes and syringe disposal at various levels of coverage (e.g., a 100% coverage level would ensure access to a sterile syringe for each injection given current levels of illicit drug injection in the United States; a 50% coverage level would ensure access to one half of the required syringes). A mathematical model of HIV transmission was employed to link programmatic coverage levels with estimates of numbers of HIV infections averted. A policy of funding syringe exchange programs, pharmacy sales, and syringe disposal to cover all illicit drug injections would cost just over $423 million U.S. for 1 year. One third of these costs would be paid for as out-of-pocket expenditures by IDUs purchasing syringes in pharmacies. Compared with the status quo, this policy would cost an estimated $34,278 U.S. per HIV infection averted, a figure well under the estimated lifetime costs of medical care for a person with HIV infection. At very high levels of coverage (>88%), the marginal cost-effectiveness of increased program coverage becomes less favorable. Although the total costs of funding large-scale IDU access to sterile syringes and disposal seem high, the economic benefits are substantial. Even at high levels of coverage, such funding would save society money. As part of a comprehensive program of HIV prevention, policies to increase IDUs access to sterile syringes urgently need further consideration by public health decision makers.

Implications of HIV treatment advances for behavioral research on AIDS: protease inhibitors and new challenges in HIV secondary prevention

Protease inhibitor combination therapies can reduce HIV viral load, improve immune system functioning, and decrease mortality from AIDS. These medical developments raise a host of critical new issues for behavioral research on HIV/AIDS. This article reviews developments in HIV combination therapy regimens and behavioral factors involved in these regimens and focuses on four key behavioral research areas: (a) the development of interventions to promote treatment adherence, (b) psychological coping with HIV/AIDS in the context of new treatments for the disease, (c) the possible influence of treatment on continued risk behavior, and (d) behavioral research in HIV prevention and care policy areas. Advances in HIV medical care have created important new opportunities for health psychologists to contribute to the well-being of persons with HIV/AIDS.

Cost-effectiveness of post-exposure prophylaxis following sexual exposure to HIV

OBJECTIVES

To assess the cost-effectiveness, relative to other health-related interventions in the U.S., of post-exposure prophylaxis (PEP) following potential HIV exposure through sexual contact with a partner who may or may not be infected, and to compare the relative cost-effectiveness of dual- and triple-combination PEP.

METHODS

Standard techniques of cost-utility analysis were used to assess the cost-effectiveness of PEP with a four-week regimen of zidovudine and lamivudine, or zidovudine, lamivudine, and indinavir. Due to a lack of empirical data on the effectiveness of PEP with combination drug regimens, the analysis assumed that combination PEP was no more effective than PEP with zidovudine alone. The main outcome variable is the cost per quality-adjusted life year (QALY) saved by the program.

RESULTS

Providing PEP to a cohort of 10,000 patients who report receptive anal intercourse with a partner of unknown HIV status (who is assumed to be infected with probability equal to 0.18) would prevent about 20 infections, at an average net cost of about US$ 70,000 per infection averted. The cost-utility ratio, US$ 6316 per QALY saved, indicates that PEP is highly cost-effective in this instance. Moreover, triple-combination PEP would need to be about 9% more effective than dual-combination PEP for the addition of indinavir to the regimen to be considered cost-effective. Prophylaxis following receptive vaginal exposure is cost-effective only when it is nearly certain that the partner is infected; PEP for insertive anal and vaginal intercourse does not appear to be cost-effective.

CONCLUSIONS

From a purely economic standpoint, PEP should be restricted to partners of infected persons (e.g., serodiscordant couples), to patients reporting unprotected receptive anal intercourse (including condom breakage), and possibly to cases where there is a substantial likelihood that the partner is infected. Providing PEP to all who request it does not appear to be an economically efficient use of limited HIV prevention and treatment resources.

Model-based evaluation of HIV prevention interventions

The ultimate goal of HIV prevention interventions is to reduce the spread of HIV; however, the effectiveness of these programs is seldom assessed directly. Although direct measurement of an intervention's impact via HIV seroincidence monitoring is usually unfeasible, mathematical models can be used to estimate the number of infections averted by the intervention. This article describes three model-based summary measures of sexually transmitted HIV risk and discusses their relevance to HIV program evaluation in general economic efficiency analyses in particular. The calculation of these measures is demonstrated with an illustrative application to previously published data from an HIV prevention intervention for gay men.

The cost-effectiveness of HIV prevention from a managed care perspective

This article offers a preliminary examination of the intersection of managed care, HIV prevention, and economic considerations. After introducing a basic framework for evaluating the cost-effectiveness of HIV prevention interventions, it reviews the cost-effectiveness literature. The article also examines how the concerns of managed care organizations impact the cost-effectiveness of HIV prevention efforts, including counseling and HIV antibody testing, small group cognitive-behavioral interventions, and community-level interventions. The article closes with a discussion of non-financial incentives for promoting HIV prevention within a managed care framework.

Cost-effectiveness of chemoprophylaxis after occupational exposure to HIV

OBJECTIVES

To assess the economic efficiency of recent US Public Health Service recommendations for chemoprophylaxis with a combination of antiretroviral drugs following high-risk occupational exposure to human immunodeficiency virus (HIV). To provide a framework for evaluating the relative effectiveness and costs associated with candidate postexposure prophylaxis (PEP) regimens.

METHODS

Standard techniques of cost-effectiveness and cost-utility analysis were used. The analysis compares the costs and consequences of a hypothetical, voluntary combination-drug PEP program consisting of counseling for all HIV-exposed health care workers, followed by chemoprophylaxis for those who elect it vs an alternative in which PEP is not offered. A societal perspective was adopted and a 5% discount rate was used. Hospital costs of recommended treatment regimens (zidovudine alone or in combination with lamivudine and indinavir) were used, following the dosing schedules recommended by the US Public Health Service. Estimates of lifetime treatment costs for HIV and acquired immunodeficiency syndrome were obtained from the literature. Because the effectiveness of combination PEP has not been established, the effectiveness of zidovudine PEP was used in the base-case analyses.

MAIN OUTCOME MEASURES

Net PEP program costs, number of HIV infections averted, cost per HIV infection averted, and cost-utility ratio (net cost per discounted quality-adjusted life-year saved) for zidovudine, lamivudine, and indinavir combination PEP. Lower bounds on the effectiveness required for combination regimens to be considered incrementally cost saving, relative to zidovudine PEP alone, were calculated. Multiple sensitivity and threshold analyses were performed to assess the impact of uncertainty in key parameters.

RESULTS

Under base-case assumptions, the net cost of a combination PEP program for a hypothetical cohort of 10,000 HIV-exposed health care workers is about $4.8 million. Nearly 18 HIV infections are prevented. The net cost per averted infection is just less than $400,000, which exceeds estimated lifetime HIV and acquired immunodeficiency syndrome treatment costs. Although combination PEP is not cost saving, the cost-utility ratio (about $37,000 per quality-adjusted life-year in the base case) is within the range conventionally considered cost-effective, provided that chemoprophylaxis is delivered in accordance with Public Health Service guidelines. Small incremental improvements in the effectiveness of PEP are associated with large overall societal savings.

CONCLUSIONS

Under most reasonable assumptions, chemoprophylaxis with zidovudine, lamivudine, and indinavir following moderate- to high-risk occupational exposures is cost-effective for society. If combination PEP is minimally more effective than zidovudine PEP, then the added expense of including lamivudine and indinavir in the drug regimen is clearly justified.

Updates of cost of illness and quality of life estimates for use in economic evaluations of HIV prevention programs

To allocate limited economic and other resources for HIV prevention and treatment for maximum benefit, health policy planners and decision makers require accurate, current estimates of the lifetime costs of HIV-related illness and the impact of therapy on the quality of life of HIV-infected persons. These data are central input parameters to the economic evaluation methodology known as cost-utility analysis. The estimates available in the literature are already outdated, and this paper presents updated estimates of the projected lifetime health care costs associated with HIV disease in the United States and the number of quality-adjusted life years (QALYs) lost to HIV in light of recent advancements in HIV diagnostics and therapeutics. Results indicate that the lifetime cost of HIV medical care has grown from about $55,000 U.S. to more than $155,000 U.S., while the number of QALYs lost per case of HIV infection has decreased from 9.26 to 7.10, when discounted at a 5% annual rate. When these figures are discounted instead at the newly recommended 3% rate, lifetime costs rise to more than $195,000 U.S. and lost QALYs increase to 11.23. The net effect of these increases in the medical costs of care and treatment saved by averting an HIV infection and in QALYs makes HIV prevention a relatively more cost-effective strategy than other, non-HIV health-related programs.

Setting standards for the Wisconsin HIV Counseling and Testing Program: an application of threshold analysis

Human immunodeficiency virus (HIV) counseling and testing (CT) services are an important component of any comprehensive HIV prevention program. Because resources are limited and must be used wisely, it is important to determine if the expenditures on CT services are sufficiently effective that they might be considered cost-saving or cost-effective to society. The policy analysis technique of "threshold analysis" was employed to determine how many HIV infections the publicly funded Wisconsin CT program would have to prevent in order to be considered cost-saving or cost-effective. Depending on the calculation method used, the threshold for the minimum number of HIV infections that must be averted ranges between approximately 1 and 18 (for the year 1994). Although the exact number of HIV infections prevented by these services in Wisconsin in unknown, the best estimate of this number is well over the required threshold. Hence, HIV CT services in the state of Wisconsin appear to be cost-saving to society.