Background
Adult male circumcision (MC) services in Kenya are provided through both horizontal and vertical programs, and via facility-based, mobile and outreach service delivery. This study assesses the costs and composition of unit costs for each program approach and service delivery mode and assess the cost-effectiveness of each.

Methods
This study was conducted on the unit costs of adult MC delivery in 222 purposively-selected MC delivery sites in Nyanza Province, Kenya from November 2008 through April 2010 using program data from the AIDS, Population, and Health Integrated Assistance Project II (APHIA II) and from the Nyanza Reproductive Health Society (NRHS). The former program can be characterized as horizontal or integrated; the latter as ‘diagonal’; containing both horizontal and vertical elements. Expenditure and services data were collected from project financial and monitoring documents and via discussions with program officials. In addition, per-case, direct service delivery costs were calculated using time and motion observations of 246 adult MC procedures performed during May and June, 2010. We calculated the cost per HIV infections averted for each of the service delivery modalities.

Results
Unit cost per adult MC was $38.62 and $44.24 for APHIA II and NRHS respectively, ranging from $29.32 (APHIA II mobile) to $46.20 (NRHS outreach/mobile). Unit costs at base facilities was similar for the two approaches. Time and motion data revealed that the opportunity cost of the elapsed time between the arrival of the surgical team and the time the first MC procedure begins varies between $2.08 and $6.27 per case. The cost per HIV infection (HIA) averted ranged from $117.29 for mobile service via the horizontal APHIA-II program to $184.84 per HIA for the diagonal NRHS program.

Conclusions
This study provides evidence for the similar efficiency of a horizontal approach (APHIA II) and a combination of horizontal and vertical approaches (NRHS) to support scale-up of adult MC services in Nyanza. Differences in unit cost are modest, not consistently in the same direction, and largely explained by differences in compensation levels.