Is isoniazid for 6 months more cost-effective than isoniazid for 9 months?

SETTING

The optimal treatment for latent tuberculosis infection consists of isoniazid (H, INH) for 9-12 months. Although INH for 6 months (6H) is more cost-effective than the 12-month regimen, the cost-effectiveness of the 6H regimen and that of INH for 9 months (9H) have not been compared.

OBJECTIVE

To compare the cost-effectiveness of treatment with 6H and 9H.

METHODS

Cost-effectiveness was evaluated using the ratio of the cost of preventing one tuberculosis case using 6H vs. 9H. The cost was estimated as the product of the number of patients to be treated to prevent one case using 6H or 9H × the cost of 6H or 9H.

RESULTS

A total of 1039 patients were studied. The number of patients that needed to be treated to prevent one case was 33 (95%CI 21-83) using 6H and 26 (95%CI 18-50) using 9H. The cost of 6H and 9H was respectively €444.34 and €578.26, and the cost ratio of preventing one case with 6H/9H was 0.98 (95%CI 0.6-1.5).

CONCLUSIONS

The cost-effectiveness of treatment with 6H and 9H is similar.