Scenario 1: national strategy scenario
Scenario 1 presents the impact of increasing the prevalence of male circumcision to 80% of HIV-negative adult males and neonates by 2012, based on the objectives expressed in the national strategy. It is assumed that the scaling up begins in 2009 and follows an S-shaped pattern to allow for training of physicians and other infrastructure developments. Although the scaling up is completed by 2012, results are presented through 2025 in order to measure the long-term impact of increasing the prevalence of male circumcision.
Figure presents the number of male circumcisions performed for the "Base" scenario, where the current prevalence rate of MC is held constant at the initial level of 10.2% throughout the time period, and the "MC" scenario, where circumcision is scaled up according to the pattern described for Scenario 1.
Number of male circumcisions performed by scenario.
The number of circumcisions performed in the "Base" scenario reflects the constant MC prevalence rate specified over the time period remaining relatively constant at around 4700 per year.
When safe male circumcision is scaled up to reach a prevalence rate of 80% by 2012, there is a rapid increase in the number of circumcisions performed for the first four years of the scenario, as the programme plays catch up with the stock of uncircumcised men, reaching a peak of over 140,000. By 2013, the number begins to drop, and the final number required levels off to reach a rate of about 43,000 circumcisions per year for the duration of the time period.
There is a strong impact of scaling up safe male circumcision on the number of new adult infections (see Figure ). While the number of new infections declines in the "Base" scenario from about 18,000 in 2007 to 13,400 by 2025, the number of new infections in the MC scenario declines even further, to reach about 7600 by 2025. Note that the decline starts when the programme begins to scale up, but then continues throughout the time period, illustrating why it is important to show the impact of the MC for a longer time period.
New adult HIV infections by scenario.
Overall, between 2008 and 2015, about 18,000 cumulative HIV infections, or 14% of total new HIV infections, are averted. Over the next 10-year time period (2016–2025), the number of cumulative new HIV infections averted reaches more than 51,000, or 38% of all new infections.
Although the primary impact of increasing the prevalence of male circumcision is to reduce the number of new HIV infections in men, the number of new HIV infections in women is also reduced via secondary impacts. Figure shows the cumulative impact from 2008–2025 of increasing male circumcision on both males and females, split into the two different age groups (15 to 29, and 30 to 49).
New adult HIV infections by scenario by age and sex, 2008–2025.
The cumulative number of new HIV infections for men drops by over 18,000 for those aged 15 to 29 and by about 26,000 for those aged 30 to 49. The cumulative number of new HIV infections for women drops by more than 17,000 for those aged 15 to 29 and by about 7000 for those aged 30 to 49.
The number of male circumcisions that are required in order to avert one HIV infection is calculated by dividing the increase in the number of male circumcisions performed by the number of HIV infections averted over the relevant time period:
where X = number of male circumcisions
Y = number of HIV infections, and
t = 2008–2015 and 2016–2025.
Between 2008 and 2015, 27.3 male circumcisions are required in order to avert one HIV infection. Because of the increasing impact of circumcision over time, however, this statistic decreases when it is calculated for the time period 2016–2025, reaching a low value of 7.3 circumcisions that need to be performed in order for an infection to be averted.
Note that this is an upper bound for this statistic as the impact of including male circumcision (especially neonatal MC) will extend beyond the current time horizon of the model. These statistics can be compared to similar statistics from other studies, including a figure of six for Lesotho, four for Swaziland, and eight for Zambia [17
The final piece to the puzzle is the cost of the programme, which needs to be evaluated relative to its effectiveness. Note that, in addition to the unit costs of male circumcision discussed here, the national strategy calls for spending 14.4 million Botswana pula (P), which equals about US$2.3 million, over five years to generate demand. Also note that after discussion, experts agreed that approximately 80% of male circumcisions would take place in the public sector, and approximately 20% would be performed by private providers.
The total net cost of the new male circumcision programme reaches a peak of $6.5 million, and then returns to a stable level of about $1.7 million per year required to maintain a circumcision prevalence rate of 80%, where net cost is defined as the total cost of all male circumcisions performed in all service delivery modes, less any user fees collected. In contrast, in the "Base" scenario, the current expenditure on male circumcision remains at about $200,000 for the duration of the timeframe (see Figure ).
Total net cost of male circumcision programme in US dollars (net of user fees collected).
The total cost by year is displayed in the first two columns of Table , along with the incremental cost in the final column, and the cumulative total for two time periods in the last two rows. The cumulative cost for implementing a scaled-up MC programme through 2015 is $23 million, while the cumulative cost between 2016 and 2025 is about $17 million, resulting in a total cumulative cost for scaled-up male circumcision through 2025 of approximately $40 million.
Net cost of scaled-up male circumcision programme (net of user fees collected)
Combining this result with the number of HIV infections averted results in a calculation of discounted net cost per HIV infection averted. Overall, the discounted net cost per HIV infection averted for the time period 2008–2015 is $1353. When the discounted net costs and number of infections averted are evaluated for the entire time period of the scenario, 2008–2025, the discounted net cost per HIV infection averted drops to $642.
In addition, net savings per HIV infection averted are calculated as the savings due to future ART costs avoided, minus the net circumcision costs, where the discounted lifetime cost of ART is based on a unit cost of P3599 in 2010 and P4135 in 2015 for first-line antiretrovirals (ARVs) with an additional $133 for second-line ARVs [18
In addition, we assume continuation rates on ART of 91% for the first year and 99% for subsequent years [16
]. The net savings, assuming a discounted lifetime cost of ART of $11,258, equals $9905 for the time period 2008–2015, and $10,616 when evaluated across the entire time period.
Net costs and savings can also be calculated relative to the number of male circumcisions performed. Net costs relative to MC performed remains about the same across the two time periods, while the net savings per circumcision performed increases substantially once the savings are evaluated over the entire time period, from $200 to $427.
Finally, a sensitivity analysis can be performed for some of the key parameters, including: the reduction in female-to-male transmission, which is assumed initially to be 60%; the reduction in male-to-female transmission, which is assumed initially to be 0%; the discount rate, which is assumed initially to be 3%; and the discounted lifetime cost of ART, which is assumed initially to be $11,000 for the purposes of this sensitivity analysis. The results of the sensitivity analysis are shown in Table . Each of the initial values of the parameters in the sensitivity analysis is shown in bolded, italicized font.
Sensitivity analysis of key parameters (2008–2025)
The results are as expected, and help to confirm the robustness of the model. If the effectiveness of male circumcision on the transmission probability is reduced so that the transmission rate is relatively higher, the number of HIV infections averted decreases, and the cost per infection averted increases. If instead the effectiveness of circumcision is higher, so that the transmission probability is reduced even further than the initial reduction of 60%, then the number of infections averted increases, and the net cost per infection decreases.
If the cost net of user fees of circumcision increases because of a higher discount rate, then the cost per infection averted increases. If the discounted lifetime cost of ART increases (decreases), then the effect is to increase (decrease) the net savings per HIV infection averted.
Given these results, the stakeholders' workshop recommended exploring further scenarios:
• Scenario 2: What is the impact of changing the target date of full coverage from 2012 to 2015?
• Scenario 3: What is the impact of reversing behaviour change that may occur due to risk compensation effects?
• Scenario 4: What is the impact of increasing the coverage of other general prevention programmes to 80% with a resulting decline in risky behaviours of 35%?