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Cost-effectiveness of HIV-prevention skills training for men who have sex with men |
Pinkerton S D, Holtgrave D R, Valdiserri R O |
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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 HIV-prevention skills training for men who have sex with men. Specifically a safer sex lecture only and the same lecture coupled with a skills-training group session.
Study population A hypothetical cohort of homosexual and bisexual men. No further details were given.
Setting Community. The economic study was carried out in Wisconsin, USA.
Dates to which data relate The main effectiveness data were derived from a series of previously published studies conducted between 1984 and 1995. Resource and cost data were obtained by retrospective estimation. The price year was 1992.
Source of effectiveness data The model parameters, base-case values and the number of quality-adjusted life years (QALY) saved per prevented infection were derived from a series of previously published studies and the authors' assumptions.
Modelling A Bernoulli-process model of HIV transmission was used to estimate the number of HIV infections averted by the skills-training intervention component. Two variants of the basic Bernoulli model were also considered. The first variant compared increases in condom use from baseline to follow-up to control for pre-intervention differences in condom-use frequency. The second alternative was used in the sensitivity analyses to provide a check on the feasibility of results suggested by the per-act model.
Outcomes assessed in the review The outcomes assessed were the model parameters, base-case values and the number of QALYs saved per prevented infection.
Study designs and other criteria for inclusion in the review No specific study designs were stipulated by the authors as inclusion criteria.
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 12 primary studies were included.
Methods of combining primary studies Investigation of differences between primary studies Results of the review The sex partners' HIV prevalence was 0.15. The number of partners per client was 2. The number of contacts with each partner was 12.5. Condom use per act was 0.52 in the group which attended only the lecture and 0.73 in the group which received the skills training course. The condom effectiveness was 0.95. The single sex act/single sex partner transmission probabilities were 0.009 and 0.1, respectively. The sex partnership overlap factor was 0.25. The number of clients in the intervention was 319. The number of groups of clients was 39. The number of sessions per client was 1. The number of hours per session was 1.33. The number of facilitators per session was 1. The facilitator's training, debriefing and preparation time was 0.5 hours per session. The time in transit per client per session was 1 hour. The number of QALYs saved per prevented infection was 6.97.
Methods used to derive estimates of effectiveness Authors' assumptions were also used to derive estimates of effectiveness.
Estimates of effectiveness and key assumptions The estimates of client transportation pro-rating factor was 0.
Measure of benefits used in the economic analysis The measures of benefits were the total number of primary and secondary infections averted and the number of QALYs saved per averted infection.
Direct costs Salaries and fringe benefits of senior project staff and facilitators who conducted the skills-training sessions were included in the analysis. The quantities were reported separately from the costs. The quantity/cost boundary adopted was that of society. A discount rate of 5% was applied. The price year was 1992.
Statistical analysis of costs Indirect Costs Utilities, rent, maintenance and general administration costs were included in the analysis. The indirect costs were obtained as a fixed percentage of the direct costs (25% in the base case). The quantities were reported separately from the costs. The quantity/cost boundary adopted was that of society. A discount rate of 5% was applied. The price year was 1992.
Sensitivity analysis One-way and multi-way sensitivity analyses were performed to assess the robustness of the base-case results to changes in modelling assumptions which determined the total incremental cost of the intervention, total number of infections averted, medical treatment cost and the number of QALYs saved per averted infection. The parameters tested were: transportation pro-rating factor, opportunity costs per hour, fringe-benefit rate, indirect cost rate, partner's/client's HIV prevalence, partners per client, contacts per partner, condom use (lecture only) and condom use (skill training groups), condom effectiveness, and sex partnership overlap factor.
Estimated benefits used in the economic analysis The total number of primary and secondary infections averted was 3.05 (57% of which were primary). The discounted QALYs saved per infection averted was 21.29.
Cost results The total direct costs were $10,125.43 (salary, $7,721.60; fringe benefits, $2,084.83; materials, $319.00). The total cost of skills training was $12,656.79 (total direct cost; indirect costs, $2,531.36; opportunity cost $0.00; transportation, $0.00). The total cost per client was $39,68. Under base-case assumptions, the incremental cost of the skills training was less than $13,000 (or about $40 per person). The discounted medical costs averted by incrementally preventing HIV infections were over $170,000.
Synthesis of costs and benefits The cost per discounted QALY saved was-$7,439.92. The intervention remains cost-saving under all conditions considered. However, the cost-utility ratio was greater than zero when worst-case values were assumed for either the total incremental cost of the intervention, the total number of infections averted and the number of QALYs saved per averted infection or for the total incremental cost of the intervention, the total number of infections averted and the medical treatment cost. When the total incremental cost of the intervention, the total number of infections averted,the medical treatment cost and the number of QALY saved per averted infection are set to worst-case values the cost-utility ratio is about $16,000 which suggests cost-effectiveness but not cost-savings.
Authors' conclusions Under most reasonable assumptions, the incremental costs of the skills training were outweighed by the medical costs saved. Thus, not only is skills training effective in reducing risky behaviour, it is also cost-saving.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator is clear. Two HIV-prevention interventions for men who have sex with men have been assessed in the analysis presented: a safer sex lecture and the same lecture coupled with a 1.5 hour skills-training group session. As the skills-training intervention led to a significant increase in condom use at 12 month follow-up compared with the lecture-only condition, this study determine whether it is worth the extra cost to add this component to an HIV-prevention intervention that would otherwise consist of a safer sex lecture only. You, as a user of this database, should consider whether these alternatives are relevant to your own setting.
Validity of estimate of measure of benefit The estimate of measure of benefit used in the economic analysis is likely to be internally valid as a systematic review of the literature was undertaken in determining baseline data within the limitation of a modelled solution. The data have not been used selectively.
Validity of estimate of costs Resource quantities were reported separately from the prices. Adequate details of the methods of quantity/cost estimation were given. Important cost items do not appear to have been omitted. As the costs have been assessed retrospectively, the current study results might suffer from some limitations.
Other issues The authors' conclusions are likely to be justified given the uncertainties in the data. The modelled solutions were tested using sensitivity analysis in order to validate the robustness of the findings. The issue of generalisability to other settings/countries was not addressed. However, appropriate comparisons were made with other studies, particularly in relation to results frombehavioural interventions to prevent the spread of HIV (i.e. number of QALYs saved per prevented infection). Results do not appear to have been presented selectively.
Implications of the study As noted by the authors, a prospective economic evaluation component to permit the collection of accurate cost data is required. Further research is required to determine more accurate characterisations of per-act or per-partner probability of HIV transmission during anal or vaginal intercourse. Detailed analyses of the sensitivity of probabilistic models, such as the Bernoulli-process model, to parameter variations are also needed as are comparisons with more complex models of HIV transmission.
Source of funding Research supported in part by grants R01-MH55440 and P30-MH52776 from the National Institute of Mental Health.
Bibliographic details Pinkerton S D, Holtgrave D R, Valdiserri R O. Cost-effectiveness of HIV-prevention skills training for men who have sex with men. AIDS 1997; 11(3): 347-357 Indexing Status Subject indexing assigned by NLM MeSH Acquired Immunodeficiency Syndrome /prevention & Bisexuality; Condoms; Cost-Benefit Analysis; Health Behavior; Homosexuality, Male /psychology; Humans; Male; Models, Theoretical; Preventive Health Services /economics; Retrospective Studies; Sex Education /economics; control AccessionNumber 21997006703 Date bibliographic record published 31/03/1999 Date abstract record published 31/03/1999 |
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