Background:  The CHAP trial showed a 43% reduction in mortality and a 23% reduction in hospital admissions with cotrimoxazole (CTX) prophylaxis in HIV-infected children (1 to 14 years) in Zambia. The cost-effectiveness of CTX prophylaxis in children following 2006 WHO guidelines is unknown and this intervention is yet to be incorporated in the basic healthcare packages of many African countries.

Methods:  A probabilistic decision analytic model of HIV/AIDS progression in children based on CD4 percentage was constructed in R and populated with epidemiological, disease progression, and resource utilisation data from the CHAP trial (median follow-up 19 months). Unit costs were measured at the University Teaching Hospital, Lusaka, using a management costing approach. In the base case, a healthcare provider perspective was adopted and cost-effectiveness estimated over the patients’ life-time. The starting cohort mirrored the characteristics of the CHAP cohort (mean age 4.4 years, 48% with AIDS, 28% with CD4%>15%). Incremental cost-effectiveness ratios (ICER) are reported in 2006 U.S. dollars.

Results:  CTX prophylaxis in a tertiary care facility in Zambia was associated with incremental cost-effectiveness ratios of $73.30 per life-year saved and $53.24 per disability adjusted life year (DALY) averted. Probabilistic analysis demonstrated a 99.6% certainty of cost-effectiveness assuming a cost-effectiveness threshold of $622 for Zambia, ie, GDP per capita 2005. Sensitivity analyses estimated the effect of including bi-monthly hematological and 6-monthly CD4 percentage monitoring; varying starting age, CD4 percentage, and AIDS status; varying percentage receiving CTX syrup; treatment effect and duration; discount rates. The intervention remained cost-effective in all sensitivity analyses and was cost-saving in children aged >9 years and those with CD4 >15%. Providing CTX prophylaxis as part of the basic healthcare package at primary healthcare facilities would be even more cost-effective with incremental cost-effectiveness ratios of $2.84 per life-year saved and $2.06 per DALY averted.

Conclusions:  CTX prophylaxis in HIV-infected children is an inexpensive low-technology intervention, which is shown to be highly cost-effective in Zambia. The intervention is cost-saving in less advanced stages of disease, further endorsing a universal strategy regardless of clinical stage or CD4 percentage. This study strongly supports the adoption of WHO guidelines into essential healthcare packages in low income countries.