Setting: University-affiliated hospital in South Africa.
Objective: To assess the time to diagnosis and the yield and laboratory cost of diagnostic procedures in human immunodeficiency virus (HIV) associated tuberculosis.
Design: Cohort study.
Patients: Adult HIV-infected patients with newly-diagnosed tuberculosis admitted over a 2-year period.
Results: A total of 141 admissions fulfilled the case definition. Sputum smear yield (43% overall) correlated strongly with chest radiograph appearance but not with CD4+ lymphocyte count. Sputum smear yield was approximately 40% per sample sent, resulting in a high cumulative yield when > or = three samples were sent. Smear of sputum or wide needle lymph node aspirates were the most cost-effective diagnostic methods. Significant diagnostic delay occurred in sputum smear-negative patients. Most patients with sputum smear-negative tuberculosis had either pleural effusions or lymphadenopathy. Lymph node biopsy had a high diagnostic yield even in patients with symmetrical nodes, but was under-utilised in this group. There was unnecessary expenditure on cultures, with many patients having several positive cultures.
Conclusion: Repeated sputum smear examination produces a high cumulative yield in HIV-associated tuberculosis. Considerable savings in laboratory utilisation and bed occupancy would have been made if a streamlined diagnostic approach with greater use of lymph node aspirate and early pleural or lymph node biopsy had been followed.