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Biomedical subjects

S D Pinkerton

Publications and source records attributed to S D Pinkerton.

At least 37 records · Page 2Linked to original sources
PubMed2000

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.

Communicable Disease Control↗
PubMed2000

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.

Dangerous Behavior↗
PubMed2000

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.

Clinical Trials as Topic↗
PubMed2000

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.

Centers for Disease Control and Prevention, U.S.↗
PubMed1999

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.

Cost of Illness↗
PubMed1999

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.

Acquired Immunodeficiency Syndrome↗
PubMed1998

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.

Adolescent↗
PubMed1998

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.

Anti-HIV Agents↗
PubMed1998

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.

Acquired Immunodeficiency Syndrome↗
PubMed1998

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.

Adolescent↗
PubMed1998

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.

Cost-Benefit Analysis↗
PubMed1998

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-Benefit Analysis↗
PubMed1998

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.

Female↗