Isoniazid prophylactic therapy for tuberculosis in HIV-seropositive patients - a least-cost analysis

The expected upsurge in the number of new cases of tuberculosis resulting from the HIV/AIDS epidemic prompted an examination of the feasibility of prevention strategies to limit the increase in clinical tuberculosis. A computer spreadsheet model was developed to estimate the costs and benefits that would result from isoniazid chemoprophylaxis for tuberculosis in a hypothetical cohort of 100 000 HIV-seropositive people in South Africa over a period of 8 years. At a 50% prevalence of tuberculosis infection among those at high background risk, and 5 - 10% among those at low risk, there would have been 34 000 cases of active tuberculosis in the cohort and their contacts if no prophylactic therapy had been used. On the other hand, a chemoprophylaxis policy would have meant only 12 200 cases of tuberculosis, if a patient compliance rate of 68,5% had been assumed. Such a policy would have prevented 21 800 cases of active tuberculosis. The estimated total discounted cost of a chemoprophylaxis programme would have been R51,3 million. In the absence of preventive therapy the discounted cost of treating patients with active tuberculosis would have been R91,9 million over the 8 year period. Therefore, if the benefits of chemoprophylaxis were defined in terms of averted health care costs, such a policy would have resulted in net savings of R40,6 million. This study did not estimate losses in production associated with tuberculosis treatment or the value of preventing tuberculosis per se, though such indirect costs would have increased the benefit of the prevention programme. Sensitivity analysis suggests that although a 6-month chemoprophylaxis policy appears justifiable on economic considerations, this is critically dependent on the annual risk of developing tuberculosis, patient compliance and the validity of assumptions on the efficacy and duration of protection of isoniazid prophylaxis

The Cost-Effectiveness of Tuberculosis Preventive Therapy for HIV-Infected Individuals in Southern India: A Trial-Based Analysis

Regimens for isoniazid-based preventive therapy (IPT) for tuberculosis (TB) in HIV-infected individuals have not been widely adopted given concerns regarding efficacy, adherence and drug resistance. Further, the cost-effectiveness of IPT has not been studied in India.We used an HIV/TB model to project TB incidence, life expectancy, cost and incremental cost-effectiveness of six months of isoniazid plus ethambutol (6EH), thirty-six months of isoniazid (36H) and no IPT for HIV-infected patients in India. Model input parameters included a median CD4 count of 324 cells/mm(3), and a rate ratio of developing TB of 0.35 for 6EH and 0.22 for 36H at three years as compared to no IPT. Results of 6EH and 36H were also compared to six months of isoniazid (6H), three months of isoniazid plus rifampin (3RH) and three months of isoniazid plus rifapentine (3RPTH).Projected TB incidence decreased in the 6EH and 36H regimens by 51% and 62% respectively at three-year follow-up compared to no IPT. Without IPT, projected life expectancy was 136.1 months at a lifetime per person cost of $5,630. 6EH increased life expectancy by 0.8 months at an additional per person cost of$100 (incremental cost-effectiveness ratio (ICER) of $1,490/year of life saved (YLS)). 36H further increased life expectancy by 0.2 months with an additional per person cost of$55 (ICER of $3,120/YLS). The projected clinical impact of 6EH was comparable to 6H and 3RH; however when compared to these other options, 6EH was no longer cost-effective given the high cost of ethambutol. Results were sensitive to baseline CD4 count and adherence.Three, six and thirty-six-month regimens of isoniazid-based therapy are effective in preventing TB. Three months of isoniazid plus rifampin and six-months of isoniazid are similarly cost-effective in India, and should be considered part of HIV care

University of the Witwatersrand Student's Medical Council

KI

Tuberculosis preventive therapy in the era of HIV infection: overview and research priorities.

The recognition of tuberculosis (TB) as a major cause of morbidity and mortality among human immunodeficiency virus (HIV)-infected persons has led to renewed interest in TB preventive therapy and its incorporation into the essential package of health care for these individuals. Despite convincing data regarding its efficacy, TB preventive therapy has not been widely implemented. Further work is needed to determine how to overcome the barriers to the implementation of such therapy, including how best to exclude the presence of active TB before providing preventive therapy. Such issues as the optimal duration of preventive therapy for and the role of TB preventive therapy in the treatment of individuals receiving antiretroviral therapy remain to be defined. Ongoing research will help to determine how best to use this intervention in the care of HIV-infected persons and in the control of TB on a wider basis