From the perspective of a payor agency, country-wide distribution of FC2 at higher volumes appears to be cost-saving relative to distribution at existing volumes. In Brazil, successful implementation of an expanded FC2 distribution program could avert over 600 new HIV infections annually, at an estimated incremental cost of $20 683 per infection averted, a figure that compares favorably with the estimated per-person cost of ART ($21 970). A similar program in South Africa was estimated to avert over 9500 new HIV infections, at an incremental cost of $985 per infection averted (versus $1503 for ART). Consequently, although expanded distribution of FC2 would avert fewer HIV infections in Brazil than in South Africa, it could be cost-effective owing to the high cost of treating a single HIV case in Brazil. In South Africa, expanded FC2 distribution would avert a larger number of infections, while the cost of ART from a government or donor perspective is relatively low. The variability in these cost-effectiveness estimates is large; the interval between the 5th and 95th percentiles often includes scenarios in which expanded FC2 distribution is more costly than ART, particularly at lower distribution volumes and in Brazil.
This analysis does not include savings from averted transmission of STI other than HIV, nor does it account for savings in HIV treatment costs other than for ART (e.g., hospitalization or treatment for opportunistic infections). Therefore, it may underestimate the savings associated with expanded FC2 distribution. However, other model assumptions may overestimate FC2 cost-effectiveness, particularly at high distribution volumes. For example, as FC2 distribution programs are expanded and reach remote populations, the proportion of FC2s not used or used to replace male condoms, as well as the cost to scale up and market FC2, may increase. Nevertheless, this analysis suggests that program effectiveness and cost-effectiveness increase substantially with increased volume. Specifically, increasing the volume of FC2s distributed from 3% to 30% of current male condom volume multiplies incremental HIV infections averted approximately 20-fold while reducing the incremental cost per infection averted. Furthermore, the incremental cost of expanded distribution could be further reduced by 45–50% if FC2s were acquired through a global purchasing mechanism with a total volume of 300 million units. These findings argue for further research to determine whether and how female condoms would be used if made available in such volume.
Sensitivity analyses suggest that the cost-effectiveness of expanded FC2 distribution depends as much on population factors driving HIV incidence (e.g., STI prevalence and sexual frequency) as on parameters describing the uptake and use of FC2 (e.g., FC2 effectiveness and fraction of FC2-protected sex acts otherwise protected by male condoms). As a result, one potential criticism of this model is its assumption that genital ulcer disease increases HIV transmission rates. To illustrate the impact of this assumption on our model results, removing the added impact of STI on HIV transmission reduces the number of HIV infections averted by 44%. However, this modification also results in modeled HIV incidence rates that would not sustain the existing prevalence of HIV [17,18] over time. In any case, this model suggests that accurate characterization of current sexual practices is critical for agencies considering the cost-effectiveness of large-scale acquisition and distribution of FC2.
Comparing expanded FC2 distribution with other interventions is difficult because the lack of available data precludes a comprehensive analysis from the societal perspective. Nevertheless, it is important to consider other HIV-prevention activities and other potentially cost-effective or cost-saving healthcare interventions [31–34] as alternatives or complements to FC2. On a gross level, a single case of HIV prevented (without ulcers, non-core group) is expected to save 54.6 disability-adjusted life years (DALY) ; therefore, FC2 expansion to moderate volume in South Africa would be expected to cost a donor or government $18 (5–95th percentiles, 11–26) per DALY saved, ignoring any cost-savings from averted HIV treatment. This figure compares with an estimated $1–74 to society per DALY saved for peer-based education, $14–261 for voluntary counseling and testing, and $350–500 for ART in the most favorable settings . However, our payor-perspective analysis ignores both important societal costs (e.g., marketing and promotion) and savings (e.g., averted productivity losses from HIV disease) of expanded FC2 distribution. Therefore, while expanded FC2 distribution may be cost saving, this analysis is not designed to test this hypothesis from a societal perspective or to compare FC2 with other interventions.
An important limitation of this analysis involves our inability to estimate precisely certain variables to which the model is sensitive. For example, variation in the fraction of distributed FC2s that are correctly used (from 64 to 100%) changes the estimated cost of country-wide FC2 distribution in Brazil from $26 351 to $16 424 per HIV infection averted (Table 4). We have attempted to account for variation in parameter values by reporting only population-averaged results with wide sensitivity analysis around those parameters associated with greatest uncertainty. Nevertheless, mis-specification of parameter values and corresponding probability distributions may bias our results, particularly at high volumes of distribution.
The model used in this analysis may also oversimplify the underlying processes of HIV infection and protection from condoms. By adopting a 1-year analysis period, assigning equivalent sexual activity to all members of the population, and assuming constant transmission risk per partner per sexual act, the model fails to account for such processes as differential condom use among a ‘core’ of highly sexually active individuals  or differential likelihood of transmission across partnerships or within partnerships over time . Other proposed models  characterize HIV transmission in greater detail; however, these models are less widely validated than the transmission model used here . Nevertheless, this transmission model was not specifically validated for the present study and, therefore, may result in over- or underestimation of FC2 impact.
Our findings suggest a number of future research directions. At present, no country distributes female condoms free of charge to a large population. Therefore, future studies should reexamine FC2 cost-effectiveness after field implementation, paying particular attention to sustained patterns of FC2 and male condom use, as well as marketing costs, in areas where FC2 becomes widely available. Second, although the World Health Organization currently recommends a new female condom for every sex act , studies of the safety and acceptability of FC2 reuse might further enhance cost-effectiveness. Third, the impact of country-wide FC2 distribution on STI other than HIV remains unclear. Finally, further analyses are needed to compare FC2 cost-effectiveness with other HIV/AIDS interventions, using a common reference scenario and a societal perspective.
In conclusion, this cost-effectiveness analysis suggests that expanded distribution of FC2 in Brazil and South Africa may avert hundreds to thousands of HIV infections annually at an incremental cost to governments or donors that is less than that of ART. These models do not include additional savings from averted hospitalization or other treatment costs, but they assume that demand for FC2 exceeds supply at all distribution volumes. Although confidence intervals are wide, and future studies are needed to assess the cost-effectiveness of FC2 after actual field implementation, these preliminary findings suggest that FC2 may be an effective and cost-saving supplement to the male condom as a preventive tool in the fight against HIV/AIDS.
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