Prospective study of a new serological test (ASSURE TB Rapid Test) for the diagnosis of pulmonary tuberculosis.

OBJECTIVE:

To prospectively compare a rapid tuberculosis serological test, ASSURE TB Rapid Test, with traditional smear and culture methods for the diagnosis of pulmonary tuberculosis (PTB).

DESIGN:

All consecutive in-patients aged > or = 18 years suspected of having active PTB and admitted between June 2001 and March 2003 were tested with three sputum samples for smear and culture of Mycobacterium tuberculosis and serology (done within 3 days).

RESULTS:

Of 238 patients initially enrolled (male: female 2.5:1, mean age 56.6 years), the final analysis included 216 patients. For the final diagnosis of PTB, the sensitivity and specificity of the serological test were respectively 60.2% (95%CI 50.5-69.1) and 82.3% (95%CI 74.2-88.2) compared to 53.4% (95%CI 43.8-62.7) and 98.2% (95%CI 93.8-99.5) for the smear test. A combination of smear and serology provided an increased sensitivity of 74.8% (95%CI 65.6-82.2), but a lower specificity of 80.5% (95%CI 72.3-86.8).

CONCLUSION:

The new serological test showed a moderate increase in sensitivity but a decrease in specificity compared to smear examination. The combination (smear + serology) test further increased the sensitivity while maintaining a moderate specificity.