Diagnostic Value of Two Rapid Immunochromatographic Tests for Suspected Tuberculosis Diagnosis in Clinical Practice
Sirisak Nanta MD*, Patcharee Kantipong MD**, Panita Pathipvanich MD***, Chidchanok Ruengorn MPH****, Chamaiporn Tawichasri MSc*****, Jayanton Patumanond DSc*****
Affiliation : * Clinical Epidemiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand ** Chiang Rai Regional Hospital, Chiang Rai, Thailand *** Lampang Regional Hospital, Lampang, Thailand **** Faculty of Pharmacy, Chiang Mai University, Chiang Mai, Thailand ***** Clinical Epidemiology Unit, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
Objective : To evaluate and compare the diagnostic value of two immunochromatographic tests for tuberculosis (ICT-TB) in
clinical practice.
Material and Method: The present extended cross-sectional study investigated suspected active TB patients at Maesai district
hospital, and Lampang regional hospital between April 2009 and May 2010. Subjects underwent two commercial ICT-TB
serum tests including: an endogenous ICT-TB, a local made test coated with 38 kD, 16 kD, and 6 kD antigens; and an
exogenous ICT-TB, an imported test coated with 38 kD and lipoarabinomanan [LAM] antigens. All subjects received two
months of follow up.
Results : Of 401 patients, 146 (36.4%) had active TB, and 206 (51.4%) were HIV seropositive. An endogenous ICT-TB was
superior to an exogenous ICT-TB in all diagnostic values measured except for specificity. In all patients, sensitivity was low,
35.6% (95% CI: 30.9-40.3) in an endogenous ICT-TB vs. 13.7% (95% CI: 10.3-17.1) in an exogenous ICT-TB. The
specificity was high and equivalent in both tests, 93.7% (95%CI: 91.4-96.1). Higher diagnostic values were found among
human immunodeficiency virus (HIV) seronegatives than in HIV seropositives when unadjusted for CD4+ cell count level.
The likelihood ratios (LHR) were higher in patients with CD4+ cell count over 200 cells/μL than for the HIV seronegative
group (LHR+ 7.6 vs. 4.8 in an endogenous ICT-TB, and 2.5 vs. 1.9 in an exogenous ICT-TB).
Conclusion : For the present study setting, an endogenous ICT-TB can be a meaningful tool for first-line testing to rule in TB
suspected cases. Subgroups of HIV seronegative and HIV seropositive patients with CD4+ cell count over 200 cells/μL may
be expected to benefit most from the test.
Keywords : Tuberculosis, HIV, Diagnostic test, Serological tests, Immunochromatographic tests
