"Tuberculosis is a big problem and it's increasing," said Paul Nunn of WHO, opening yesterday's session on tuberculosis (TB) prevention and management. Fifteen million persons with TB are co-infected with HIV, 11 million of them in sub-Saharan Africa. Currently, TB management relies on case finding and treatment. "The role of preventive therapy in the South is not yet clear," Nunn said.

Prevention with isoniazid (INH) is cost-effective in sub-Saharan Africa, reported Jensa Bell of Mt. Sinai Hospital, New York. Direct medical costs of isoniazid for six months are CHF171 per year of life saved. When you include the social costs of TB and prevention of secondary cases, INH prophylaxis saves money: initial investment is CHF34.50 per person treated, while cost averted is CHF36.24 per person treated. "This shows that preventive therapy for TB is a cost-effective way of extending healthy life of HIV-infected patients and of controlling TB in developing countries," Bell said.

Mary Mulindwa, of the Joint Clinical Research Centre in Kampala, Uganda, evaluated reasons for non-adherence to TB preventive regimens in a clinical trial. Major reasons for missing scheduled clinic visits were transport difficulties, caring for a sick family member, change of address without telling the home visitor and stigma of being seen with a health worker. Steps to counter these obstacles need to be devised, she said.

Richard Chaisson of the CPCRA004/ACTG177 study group reported results from a trial comparing prevention with INH for 12 months to rifampin (R) plus pyrazinamide (P) for two months in 1600 tuberculin-positive, HIV-positive persons without active disease in the US, Mexico, Brazil and Haiti. Patients took drugs at home without supervision. "Effective therapy" with INH was considered to be at least six months of continuous adherence; two-thirds of patients met this standard. Adherence with R/P was 80%. Over three years, confirmed TB cases were equivalent between the two regimens, 19 with R/P and 26 with INH, showing that both prevent TB in these patients. However, Chaisson noted, "Cost and feasibility [of R/P] in resource-poor settings is an important consideration."

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