Cost-effectiveness of rifampin for 4 months and isoniazid for 9 months in the treatment of tuberculosis infection.

The purpose of this study was to evaluate the cost-effectiveness of the strategy of controlling the contacts of tuberculosis patients with latent tuberculosis infection by means of treatment with rifampin for 4 months or isoniazid for 9 months. The cost was the sum of the cost of treating latent tuberculosis infection in all contacts plus the cost of treating tuberculosis in whom the disease was not avoided. The effectiveness was expressed as cases avoided. The efficacy adopted was 90 % for rifampin for 4 months and 93 % for isoniazid for 9 months. We carried out a sensitivity analysis for efficacies of rifampin for 4 months of 80 %, 75 %, 69 % and 65 %. Of the 1,002 patients studied, 139 were treated with rifampin for 4 months and 863 were treated with isoniazid for 9 months. The cost-effectiveness was <euro>436,842.83/50 cases avoided with rifampin for 4 months and <euro>692,164.42/40 cases avoided with isoniazid for 9 months. Rifampin for 4 months was dominant. In the sensitivity analysis, rifampin for 4 months was dominant for efficacies of 75 % or greater. The cost-effectiveness analysis favoured the use of rifampin for 4 months when its efficacy was 75 % or greater.