A Bayesian Approach to Net Health Benefits: An Illustration and Application to Modeling HIV Prevention

Purpose. To conduct a cost-effectiveness analysis of HIV prevention when costs and effects cannot be measured directly. To quantify the total estimation of uncertainty due to sampling variability as well as inexact knowledge of HIV transmission parameters. Methods. The authors focus on estimating the incremental net health benefit (INHB) in a randomized trial of HIV prevention with intervention and control conditions. Using a Bernoulli model of HIV transmission, changes in the participants’ risk behaviors are converted into the number of HIV infections averted. A sampling model is used to account for variation in the behavior measurements. Bayes’s theorem and Monte Carlo methods are used to attain the stated objectives. Results. The authors obtained a positive mean INHB of 0.0008, indicating that advocacy training is just slightly favored over the control condition for men, assuming a $50,000 per quality-adjusted life year (QALY) threshold. To be confident of a positive INHB, the decision maker would need to spend more than $100,000 per QALY.

An economic analysis of management strategies for closed and open grade I tibial shaft fractures

BACKGROUND

Closed and open grade I (low-energy) tibial shaft fractures are a common and costly event, and the optimal management for such injuries remains uncertain.

METHODS

We explored costs associated with treatment of low-energy tibial fractures with either casting, casting with therapeutic ultrasound, or intramedullary nailing (with and without reaming) by use of a decision tree.

RESULTS

From a governmental perspective, the mean associated costs were USD 3,400 for operative management by reamed intramedullary nailing, USD 5,000 for operative management by non-reamed intramedullary nailing, USD 5,000 for casting, and USD 5,300 for casting with therapeutic ultrasound. With respect to the financial burden to society, the mean associated costs were USD 12,500 for reamed intramedullary nailing, USD 13,300 for casting with therapeutic ultrasound, USD 15,600 for operative management by non-reamed intramedullary nailing, and USD 17,300 for casting alone.

INTERPRETATION

Our analysis suggests that, from an economic standpoint, reamed intramedullary nailing is the treatment of choice for closed and open grade I tibial shaft fractures. Considering financial burden to society, there is preliminary evidence that treatment of low-energy tibial fractures with therapeutic ultrasound and casting may also be an economically sound intervention.

Cost-Effectiveness of a Community-Level HIV Risk Reduction Intervention for Women Living in Low-Income Housing Developments

We conducted a cost-effectiveness analysis of a multi-site community-level HIV prevention trial that enrolled women living in 18 low-income housing developments in 5 U.S. cities. A mathematical model of HIV transmission was used to estimate the number of HIV infections averted and quality-adjusted life years (QALYs) saved by the community-level intervention, based on data obtained from community-wide sexual behavior surveys at baseline and 12-month follow-up. Results indicated that the intervention prevented approximately 1 infection per 3500 women reached by the intervention, at a total cost of 174,845 dollars. The cost per QALY saved by the intervention was 37,433 dollars and the cost per HIV infection averted was 732,072 dollars. The community-level intervention was moderately cost-effective in comparison with other HIV prevention programs for at-risk women. Synergistic approaches to HIV prevention that combine community-level sexual norm change interventions with more intensive risk reduction programs for high-risk women are needed. EDITORS' STRATEGIC IMPLICATIONS: The authors present a promising and efficient community-level HIV prevention approach, with effects beyond the limited scope of individual or small group interventions. This paper represents an example of how an analysis of cost-effectiveness can provide policymakers with information needed for difficult decisions about prevention resource allocations.

Healthy Growth: project description and baseline findings

OBJECTIVES

The purpose of the study was to describe the physical activity, blood pressure, and body fat patterns of sixth-grade, African-American girls (N = 82), who participated in the Healthy Growth Study. The purpose of the primary study questions was to determine which sets of variables best predict blood pressure, physical activity, and body fat.

DESIGN AND METHODS

This paper is a cross sectional analysis of the first assessment of a 5-year longitudinal project. Standard procedures were used to assess height, weight, skinfolds, blood pressure, physical activity, predictors of physical activity, maturation, dietary intake, fitness level, and health behaviors.

RESULTS

The average age of the subjects was 12.3 years; almost two-thirds of the girls had reached menarche. Fifty-two percent of the 13-year-olds had body mass index (BMI) values greater than the 85th percentile for their age and sex compared to 32% of the 12-year-olds. None of the variables were significantly related to diastolic or systolic blood pressure. Physical activity was significantly and negatively related to total percent of calories from fat and to breast stages and positively related to waist/thigh ratio. Body mass index (BMI) was significantly and positively related to breast stages.

CONCLUSIONS

Important developmental differences between 12- and 1 3-year-olds were evident. Body mass index (BMI) was mainly dependent on physical maturity. No relationship was found between BMI and blood pressure. The relationship between physical activity and waist/thigh ratio merits further study. The importance of BMI and physical inactivity as potential indicators of cardiovascular risk in adolescent girls is discussed. Developmentally appropriate and culturally competent interventions are recommended to increase physical activity and healthy eating behaviors among adolescents.

Efficacy and cost-effectiveness of the first generation of HIV prevention interventions for people with severe and persistent mental illness

BACKGROUND

People with serious mental illness are at elevated risk for human immunodeficiency virus (HIV) infection. A small body of published research has evaluated the efficacy of HIV prevention interventions that aim to help persons with mental illness modify sexual behaviors that place them at risk for HIV infection. Additional research has evaluated the economic efficiency ('cost-effectiveness') of these interventions.

AIMS OF THE STUDY

We provide a detailed and critical review of the efficacy and cost-effectiveness of randomized, controlled trials of HIV prevention interventions for this population. We present a brief overview of the epidemiology of HIV among men and women with serious mental illness and describe HIV risk factors for members of this population. The efficacy literature is critically reviewed, and the results of the available studies are compared using a common effect size metric. The cost-effectiveness of HIV prevention interventions for mentally ill adults is then reviewed.

METHODS

The efficacy of interventions at reducing risk behaviors and increasing preventive behaviors was summarized using effect size estimation techniques. First, we reviewed interventions that have been evaluated in randomized clinical trials and published in the peer-reviewed scientific literature so as to summarize the interventions that have been subjected to the most rigorous evaluation. For each of the five studies that met the inclusion criteria, we briefly described the methodology and intervention content, summarized the evidence for intervention efficacy, and calculated appropriate effect size estimates. A narrative review of two cost-effectiveness studies published to date was included.

RESULTS

The review of intervention efficacy indicated that the risk reduction interventions evaluated to date have had only limited success at helping people with severe mental illness reduce their HIV risk behavior. Most effect sizes indicating successful condom use increases were in the small or small to moderate range. Overall, studies with the largest sample sizes, and presumably the most generalizable results, produced smaller intervention effect sizes than studies with smaller samples. The cost-effectiveness literature revealed similarly mixed results: economic efficiency varied from not cost-effective to highly cost-effective.

DISCUSSION

Limited information is presently available regarding the efficacy and cost-effectiveness of HIV prevention interventions for people with severe and persistent mental illness. Encouraging results were obtained in some, but not all studies. Methodological limitations will need to be addressed in the next generation of HIV risk reduction intervention studies for this population.

IMPLICATIONS FOR HEALTH CARE PROVISION AND USE

Persons with severe mental illness warrant attention from health care providers due to elevated risk for HIV infection. Interventions discussed herein, focusing on information and behavioral skills training, can be employed until strategies with stronger results are developed.

IMPLICATIONS FOR HEALTH POLICIES

Effective and cost-effective HIV risk reduction interventions are available for adults with mental illness and should be more widely implemented. The cost-effectiveness of these interventions could be further enhanced by screening potential participants for high-risk sexual behaviors.

IMPLICATIONS FOR FURTHER RESEARCH

To advance the field, the next generation of intervention research for people with severe mental illness will need to improve upon the designs and intervention strategies of the first generation, include larger samples, and devote increased attention to the life circumstances and particular mental health issues of intervention participants.

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.

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.

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.

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.

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.

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.