Subclinical tuberculosis among HIV-infected adults: Clinical features and outcomes in a South African cohort

Abstract

OBJECTIVE: Describe the prevalence, clinical characteristics, and mortality risk for HIV-infected adults with subclinical tuberculosis. DESIGN: Untreated HIV-infected adults presenting for outpatient care in Durban, South Africa were screened for tuberculosis-related symptoms and had sputum tested by acid-fast bacilli smear and tuberculosis culture. Active tuberculosis and subclinical tuberculosis were defined as having any tuberculosis symptom or no tuberculosis symptoms with either smear-positive or culture-positive sputum. We evaluated the association between tuberculosis disease category and 12-month survival. RESULTS: Among 670 participants, 106 were diagnosed with active tuberculosis disease and 34 with subclinical disease. The mean CD4 count was 138 cells/mm3 in patients with active tuberculosis, 200 cells/mm3 in patients with subclinical disease, and 289 cells/mm3 in those without tuberculosis disease (P <0.001). A greater proportion of individuals in the subclinical group were smear positive (41%) compared to the active tuberculosis group (22%, P 0.04). Risk of mortality was not increased in individuals with subclinical tuberculosis relative to no tuberculosis (adjusted hazard ratio 0.74, 95% CI 0.23-2.40). CONCLUSION: Subclinical tuberculosis in HIV-infected adults was characterized by an intermediate degree of immunosuppression and greater sputum smear positivity. Although there was no significant difference in survival, these findings have important implications for preventing tuberculosis transmission.