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S E T T I N G : Enhanced tuberculosis (TB) case finding
using detection rats in Tanzania.
O B J E C T I V E S : To assess the diagnostic accuracy of
detection rats compared with culture and Xpert w MTB/
RIF, and to compare enhanced case-finding algorithms
using rats in smear-negative presumptive TB patients.
D E S I G N : A fully paired diagnostic accuracy study in
which sputum of new adult presumptive TB patients in
Tanzania was tested using smear microscopy, 11
detection rats, culture and Xpert.
R E S U LT S : Of 771 eligible participants, 345 (45%) were
culture-positive for Mycobacterium tuberculosis, and
264 (34%) were human immunodeficiency virus (HIV)
positive. The sensitivity of the detection rats was up to
75.1% (95%CI 70.1–79.5) when compared with cul-
ture, and up to 81.8% (95%CI 76.0–86.5) when
compared with Xpert, which was statistically signifi- cantly higher than the sensitivity of smear microscopy.
Corresponding specificity was 40.6% (95%CI 35.9–
45.5) compared with culture. The accuracy of rat
detection was independent of HIV status. Using rats
for triage, followed by Xpert, would result in a
statistically higher yield than rats followed by light-
emitting diode fluorescence microscopy, whereas the
number of false-positives would be significantly lower
than when using Xpert alone.
C O N C L U S I O N : Although detection rats did not meet
the accuracy criteria as standalone diagnostic or triage
testing for presumptive TB, they have additive value as a
triage test for enhanced case finding among smear-
negative TB patients if more advanced diagnostics are
not available |
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