Diagnostic yield of tuberculosis using sputum induction in HIV-positive patients before antiretroviral therapy

Adults (n = 602) enrolling in a South African antiretroviral treatment clinic underwent culture-based screening for tuberculosis (TB), regardless of symptoms. For those unable to spontaneously expectorate a 'spot' sample (n = 124), sputum induction with nebulised hypertonic saline was used to obtain a first sample and also to rapidly obtain a second sample from all patients. Collection of both samples typically took 10-15 min. The prevalence of culture-positive TB was 15.6% (95%CI 12.8-18.8). Spontaneously expectorated spot samples yielded 79.8% of all culture-positive TB diagnoses. The incremental yield from those needing an induced first sample was 5.3% and the yield from induced second samples was 14.9%.