Evaluation of a diagnostic algorithm for smear-negative pulmonary tuberculosis in HIV-infected adults

To evaluate the diagnostic accuracy of and reduction in diagnostic delay attributable to a clinical algorithm used for the diagnosis of smear-negative pulmonary tuberculosis (SNPTB) in HIV-infected adults.

An algorithm was designed to facilitate clinicoradiological diagnosis of pulmonary TB (PTB) in HIV-infected smear-negative adult patients. A folder review was performed on the first 58 cases referred for empirical TB treatment using this algorithm.

Nolungile HIV Clinic, Site C, Khayelitsha.

Subjects included 58 HIV-infected adult patients with suspected PTB consecutively referred to the local TB clinic for outpatient TB treatment using this algorithm between 12 February 2004 and 30 April 2005.

Outcome measures were response of C-reactive protein, haemoglobin, weight and symptoms to TB treatment, and TB culture result. Diagnostic delay (in days) was calculated.

Thirty-two of the 58 patients (55%) had positive TB cultures (definite TB). Initiation of TB treatment occurred on average 19.5 days before the positive culture report. A further 21 patients (36%) demonstrated clinical improvement on empirical treatment (probable/possible TB). Two patients did not improve and subsequently died without a definitive diagnosis. Three patients defaulted treatment.

SNPTB is more common in HIV-infected patients and leads to diagnostic delay. This algorithm allowed for earlier initiation of TB treatment in HIV-infected patients presenting with symptoms of PTB and negative smears or nonproductive cough in a high TB incidence setting.