Cost-effectiveness of a community-level HIV risk reduction intervention Pinkerton S D, Holtgrave D R, DiFranceisco W J, Stevenson L Y, Kelly J A

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1 Cost-effectiveness of a community-level HIV risk reduction intervention Pinkerton S D, Holtgrave D R, DiFranceisco W J, Stevenson L Y, Kelly J A Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Community-level HIV prevention intervention using peer leaders to support risk reducing behaviour amongst gay men. Type of intervention Primary prevention. Economic study type Cost-effectiveness analysis and cost-utility analysis. Study population Men frequenting gay bars. Setting Community. The economic study was carried out in Milwaukee, USA. Dates to which data relate Effectiveness data concerning changes in sexual behaviour were derived from a study undertaken in Resource and cost data for the intervention relate to 1996 levels. Lifetime costs associated with HIV care were derived from a study published in The price year was Source of effectiveness data Effectiveness data concerning changes in sexual behaviour were derived from a single study. The parameters used to extrapolate these changes in behaviour into cases of HIV avoided were derived from published studies and expert opinion. Link between effectiveness and cost data Resource use and cost data associated with the intervention were determined retrospectively. Study sample There was no formal determination of sample size or power calculation: the sample surveyed was determined by the number of patrons at the respective sites during the 3 day sampling period. All patrons were surveyed once during each survey period, and 81% completed the survey questionnaire. There were 328 pre-intervention surveys completed at the intervention site and 330 at the control sites. 278 post-intervention surveys were completed for the intervention site and 330 for the control sites. Page: 1 / 5

2 Study design The study was a non-randomised trial with concurrent controls. The trial involved one intervention site and two control sites. Follow-up surveys were undertaken at 3 and 6 months following the intervention. The participants completing the surveys were blind to the study intervention. Analysis of effectiveness The analysis was based on intention to treat, given that all respondents were included regardless of whether they received the intervention and all completed either, or both, of the pre or post intervention surveys. The primary outcomes from the study were sexual behaviour characteristics: percentage engaging in unprotected anal intercourse, condom use, number of sexual partners. These outcomes were obtained through the use of self-completed questionnaires. The populations of the intervention and control sites were comparable. Effectiveness results The study found a reduction in the number of sexual partners, a reduction in the percentage of unprotected anal intercourse and an increase in the use of condoms for the intervention site, which were not evident in the comparison sites. Clinical conclusions The conclusion of the study is that a community level intervention utilising peer leaders can alter HIV risk behaviour amongst gay men. Modelling An epidemiological model was used to extrapolate from base results concerning changes in sexual habits to estimates of the number of cases of HIV averted and the number of quality adjusted life years (QALYs) saved due to the prevention intervention. Outcomes assessed in the review The following parameters, used within the model, were assessed from the literature: the prevalence of HIV in the community, per-act probability of HIV transmission for receptive anal intercourse, condom effectiveness and QALYs saved per prevented infection. Study designs and other criteria for inclusion in the review No specific design criteria were identified by the authors for inclusion. The date for the information was Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included 10 studies were used. Page: 2 / 5

3 Methods of combining primary studies Investigation of differences between primary studies Not stated Results of the review The prevalence of HIV in the community was reported to be 9%,the per-act transmission probability was 0.9% for receptive intercourse, condom effectiveness was reported as 95%, quality-adjusted life years were reported as saved per prevented infection. Methods used to derive estimates of effectiveness Expert opinion. Estimates of effectiveness and key assumptions The per-act probability of transmission for insertive anal intercourse was estimated to be 0.09%. Measure of benefits used in the economic analysis For the cost-effectiveness analysis the measure of benefit was given as cases avoided. For the cost-utility analysis quality adjusted life years saved was used as the measure of benefit. Direct costs Costs associated with staff compensation payments, incentives for peer leaders to get involved with the intervention, materials, travel expenses, rent, catering and overheads were determined retrospectively and included within the analysis. The lifetime medical care costsassociated with HIV and AIDS, determined from a published study, were included in the analysis. The future costs were discounted at an annual rate of 3%. The quantity/cost boundary adopted was that of the health service. All costs were in 1996 dollars. Statistical analysis of costs Not undertaken. Indirect Costs Not assessed. Currency US dollars ($). Sensitivity analysis Sensitivity analysis was carried out on the number of infections averted, effectiveness of condoms, prevalence of infection in the community and the transmission probabilities. The impact of three discount rates was determined (0%, 3% and 5%). Nine scenarios concerning the levels of HIV medical care required were investigated. Little information was provided concerning the sensitivity analysis itself or its results. Page: 3 / 5

4 Estimated benefits used in the economic analysis The intervention was credited with preventing HIV infections and saving just under 3 quality adjusted life years (discounted at 3%) on the basis of the intervention being effective at altering behaviour for 2 months. Cost results The costs associated with the intervention were $17,150, or $65,458 per case of HIV averted. The lifetime costs of care associated with HIV are $87,045 per case (discounted at 3%). An incremental analysis showed that the intervention was cost saving:$5,656 per intervention, $21,587 per case. Synthesis of costs and benefits Costs and benefits were not synthesised as the intervention was associated with lower cost and better outcomes for the patient. Under these assumptions the intervention was the dominant strategy. The results of the sensitivity analysis indicated that the intervention remained cost-saving under all of the assumptions and scenarios examined. Authors' conclusions Community-level HIV prevention programmes, using peer leaders to endorse risk reducing behaviour, are cost-saving compared to no intervention under a set of reasonable assumptions, with an initial outlay for the intervention which is affordable for most community based AIDS prevention organisations. CRD COMMENTARY - Selection of comparators The reason for the choice of comparator is clear. Validity of estimate of measure of benefit Few details were given concerning the determination of the model parameters. Hence it is difficult to assess the internal validity of the results. The authors noted that the estimation of key parameters and the modelling undertaken represent limitations in the study, but they suggested that the sensitivity analysis which was undertaken mitigated these concerns. However, the extent to which this is true is difficult to assess given the lack of details and results from the sensitivity analysis. Validity of estimate of costs The authors noted that the retrospective collection of cost data was a limitation of the study. No resource quantities were given, and there were no details about the method used to estimate the costs. Other issues The authors noted that the results may not be generalisable to other settings with different risk levels, attitudes and startup costs. Implications of the study The authors suggested that further studies are needed to determine the cost-effectiveness of community-level and other HIV prevention interventions within a "real world" context. Source of funding Supported in part by grants R01-MH55440 and R01-MH42908 from the National Institute of Mental Health (NIMH) and by NIMH Center grant P30-MH Page: 4 / 5

5 Powered by TCPDF ( Bibliographic details Pinkerton S D, Holtgrave D R, DiFranceisco W J, Stevenson L Y, Kelly J A. Cost-effectiveness of a community-level HIV risk reduction intervention. American Journal of Public Health 1998; 88(8): PubMedID Indexing Status Subject indexing assigned by NLM MeSH Communicable Disease Control /economics; Consumer Participation /economics; Cost-Benefit Analysis; HIV Infections /economics /prevention & control /transmission; Health Education /economics; Health Knowledge, Attitudes, Practice; Homosexuality, Male /statistics & numerical data; Humans; Male; Models, Economic; Quality-Adjusted Life Years AccessionNumber Date bibliographic record published 28/02/1999 Date abstract record published 28/02/1999 Page: 5 / 5