Has universal screening with Xpert® MTB/RIF increased the proportion of multidrug-resistant TB cases diagnosed in a routine operational setting?
Abstract
Setting
Primary health services in
Cape Town, South Africa where the introduction of Xpert®
MTB/RIF (Xpert) enabled simultaneous screening for tuberculosis
(TB) and drug susceptibility in all presumptive cases.
Study aim
To compare the proportion
of TB cases with drug susceptibility tests undertaken and
multidrug-resistant tuberculosis (MDR-TB) diagnosed
pre-treatment and during the course of 1st line treatment in the
previous smear/culture and the newly introduced Xpert-based
algorithms.
Methods
TB cases identified in a
previous stepped-wedge study of TB yield in five sub-districts
over seven one-month time-points prior to, during and after the
introduction of the Xpert-based algorithm were analysed. We used
a combination of patient identifiers to identify all drug
susceptibility tests undertaken from electronic laboratory
records. Differences in the proportions of DST undertaken and
MDR-TB cases diagnosed between algorithms were estimated using a
binomial regression model.
Results
Pre-treatment, the
probability of having a DST undertaken (RR = 1.82)(p<0.001)
and being diagnosed with MDR-TB (RR = 1.42)(p<0.001) was
higher in the Xpert-based algorithm than in the
smear/culture-based algorithm. For cases evaluated during the
course of 1st-line TB treatment, there was no significant
difference in the proportion with DST undertaken (RR = 1.02)(p =
0.848) or MDR-TB diagnosed (RR = 1.12)(p = 0.678) between
algorithms.
Conclusion
Universal screening for
drug susceptibility in all presumptive TB cases in the
Xpert-based algorithm resulted in a higher overall proportion of
MDR-TB cases being diagnosed and is an important strategy in
reducing transmission. The previous strategy of only screening
new TB cases when 1st line treatment failed did not compensate
for cases missed pre-treatment.
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Source:
PLOS ONE
