Assessment of the Diagnostic Potential of Clinotech TB Screen Test for Diagnosis of Pulmonary Tuberculosis in Nigeria

Abstract

The Clinotech TB Screen test, a 3rd generation multi-antigen rapid chromatographic immunoassay for detection of IgG antibodies in serum against recombinant protein antigens 38kDa, 16kDa and 6kDa, was assessed for its diagnostic potential for diagnosis of active pulmonary TB in routine TB control programme in Abia State, Nigeria. The overall sensitivity and specificity of Clinotech TB Screen test were 24.1% and 87.8% (95% Confidence intervals [CI]: 14.7-33.5% and 80.6-95.0%) respectively. The positive and Negative Predictive Values (PPV and NPV) were 79.2% and 37.5% respectively. The performance of the test was inferior to that of the sputum smear microscopy which had a sensitivity of 50.0% (95% CI, 39.0%-61.0%) and specificity of 92.3(95% CI: 86.4-98.2%). In 37 culture positive smear positive PTB cases, Clinotech TB Screen test was positive in 18(48.65%). The rapid test showed a very low degree of sensitivity in smear –negative culture positive PTB cases; detecting just one (2.38%) out of 42 cases. These results indicate that the diagnostic value of Clinotech TB Screen test for routine diagnosis of PTB in this setting is limited.

Key words: Tuberculosis, serological tests, immunochromatographic tests, rapid TB tests