Effectiveness of cotrimoxazole prophylaxis on mortality in adults with tuberculosis in rural South Africa

Background: Adults with dual tuberculosis (TB) and HIV infection have a poor outcome. Studies in West Africa suggest that cotrimoxazole prophylaxis may reduce this mortality. Objective: To evaluate the effectiveness of cotrimoxazole in reducing mortality in adults with active TB, irrespective of HIV status, in a high prevalence setting. Design: Cohort study using historical controls. Methods: Adults treated for TB between 1998 and 2000 were traced and vital status at 6 months ascertained (2004: control group). All adults starting treatment for TB between June 2001 and June 2002 were offered cotrimoxazole prophylaxis 960 mg once daily for 6 months during TB treatment irrespective of HIV status (1321: intervention group). Mortality, adverse reactions and adherence were compared between intervention and control groups. Results: HIV seroprevalence in patients with TB at the start of the intervention was estimated to be 78%. Mortality at 6 months was 29% lower in the group given cotrimoxazole than in the control group. The number needed to treat to prevent one death during the period of TB treatment was 24. The benefit was seen across all types of TB but was only evident in new patients; patients being retreated had similar outcomes in both groups. Adverse events were infrequent and minor, with only two participants having treatment stopped for this reason. Conclusion: Cotrimoxazole prophylaxis for all adults with TB, irrespective of HIV status, in an area of high HIV seroprevalence may be a feasible, safe and effective way to reduce mortality for the duration of treatment