Cotrimoxazole for children with HIV highly cost-effective

Cotrimoxazole prophylaxis for children with HIV in Zambia is highly cost-effective, according to an analysis of data from the CHAP trial, published this month in AIDS.

The Children with HIV Antibiotic Prophylaxis trial, which reported its main results in 2004, demonstrated that cotrimoxazole prophylaxis in children aged one to 14 years reduced the risk of death by 43%, and also reduced hospitalisation.

According to later analysis of the trial results, cotrimoxazole reduced the risk of death and serious illness primarily by reducing the incidence of serious bacterial lung infections, rather than by reducing the incidence of PCP pneumonia (only one case of PCP was seen in the CHAP study).

Despite these findings, countries in sub-Saharan Africa have been slow to implement cotrimoxazole prophylaxis for children. UNAIDS estimates that up to four million children with HIV who could benefit from cotrimoxazole prophylaxis do not receive it, either because they are undiagnosed or due to lack of access.

A major reason for lack of access, say the authors of the cost-effectiveness review, is the competition for resources among many priorities.

In order to provide evidence that might encourage allocation of resources to paediatric treatment, the authors used data from the CHAP study on the incidence of illness, death and hospitalisation, together with CD4 cell percentage measurements, to calculate the cost-effectiveness of cotrimoxazole treatment compared with no prophylaxis.

Cost-effectiveness was measured in terms of quality-adjusted life years and disability-adjusted life years saved by giving cotrimoxazole prophylaxis.

The incremental cost-effectiveness of an intervention represents the extra cost of a health intervention compared with doing nothing, or continuing existing practice, and this amount will vary from one setting to another according to health system costs.

Cost-effectiveness is generally assumed if an intervention costs less than a country’s GDP per life year saved.

In the case of Zambia, cotrimoxazole had an incremental cost-effectiveness ratio of $72 per life-year saved, compared with a national GDP of $1019 per capita, when delivered through hospital outpatient clinics.

However, it became even more cost-effective when delivered through primary health care - $4 per life year saved – and the authors say that they found the cost-effectiveness of cotrimoxazole to be highly sensitive to the cost of outpatient visits, arguing for the deregulation of cotrimoxazole prescribing to nurses and other cadres of health care workers.

In comparison one study has found that adult antiretroviral therapy (using data derived from the Khayelitsha clinic cohort in South Africa in 2006) has an incremental cost-effectiveness ratio of $984 per life-year saved, making it cost-effective in the South African setting. No estimate of the cost-effectiveness of antiretroviral therapy in children is available.