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Naidoo, Pren, Dunbar, Rory, Lombard, Carl, du Toit, Elizabeth, Caldwell, Judy, Detjen, Anne, Squire, Bertie 
ORCID: https://orcid.org/0000-0001-7173-9038, Enarson, Donald A and Beyers, Nulda
(2016)
'Comparing Tuberculosis Diagnostic Yield in Smear/Culture and Xpert® MTB/RIF-Based Algorithms Using a Non-Randomised Stepped-Wedge Design'. PLoS ONE, Vol 11, Issue 3, e0150487.
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PLoS_One_11_3_Comparing tuberculosis diagnostic yield.PDF - Published Version Available under License Creative Commons Attribution. Download (512kB) | Preview |
Abstract
Setting
Primary health services in Cape Town, South Africa.
Study Aim
To compare tuberculosis (TB) diagnostic yield in an existing smear/culture-based and a newly introduced Xpert® MTB/RIF-based algorithm.
Methods
TB diagnostic yield (the proportion of presumptive TB cases with a laboratory diagnosis of TB) was assessed using a non-randomised stepped-wedge design as sites transitioned to the Xpert® based algorithm. We identified the full sequence of sputum tests recorded in the electronic laboratory database for presumptive TB cases from 60 primary health sites during seven one-month time-points, six months apart. Differences in TB yield and temporal trends were estimated using a binomial regression model.
Results
TB yield was 20.9% (95% CI 19.9% to 22.0%) in the smear/culture-based algorithm compared to 17.9% (95%CI 16.4% to 19.5%) in the Xpert® based algorithm. There was a decline in TB yield over time with a mean risk difference of -0.9% (95% CI -1.2% to -0.6%) (p<0.001) per time-point. When estimates were adjusted for the temporal trend, TB yield was 19.1% (95% CI 17.6% to 20.5%) in the smear/culture-based algorithm compared to 19.3% (95% CI 17.7% to 20.9%) in the Xpert® based algorithm with a risk difference of 0.3% (95% CI -1.8% to 2.3%) (p = 0.796). Culture tests were undertaken for 35.5% of smear-negative compared to 17.9% of Xpert® negative low MDR-TB risk cases and for 82.6% of smear-negative compared to 40.5% of Xpert® negative high MDR-TB risk cases in respective algorithms.
Conclusion
Introduction of an Xpert® based algorithm did not produce the expected increase in TB diagnostic yield. Studies are required to assess whether improving adherence to the Xpert® negative algorithm for HIV-infected individuals will increase yield. In light of the high cost of Xpert®, a review of its role as a screening test for all presumptive TB cases may be warranted.
| Item Type: | Article |
|---|---|
| Subjects: | WC Communicable Diseases > Virus Diseases > Acquired Immunodeficiency Syndrome. HIV Infections > WC 503.5 Complications WF Respiratory System > Tuberculosis > WF 200 Tuberculosis (General) WF Respiratory System > Tuberculosis > WF 220 Diagnosis. Prognosis |
| Faculty: Department: | Clinical Sciences & International Health > Clinical Sciences Department |
| Digital Object Identifer (DOI): | https://doi.org/10.1371/journal.pone.0150487 |
| Depositing User: | Jessica Jones |
| Date Deposited: | 03 Mar 2016 12:13 |
| Last Modified: | 13 Nov 2019 11:22 |
| URI: | https://archive.lstmed.ac.uk/id/eprint/5716 |
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