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Comparative Study
. 2016 Mar 29;11(3):e0152364.
doi: 10.1371/journal.pone.0152364. eCollection 2016.

Comparative Yield of Different Diagnostic Tests for Tuberculosis among People Living with HIV in Western Kenya

Joseph S Cavanaugh  1 , Surbhi Modi  1 , Susan Musau  2 , Kimberly McCarthy  1 , Heather Alexander  1 , Barbara Burmen  2 , Charles M Heilig  1 , Ray W Shiraishi  1 , Kevin Cain  3
Affiliations
Comparative Study

Comparative Yield of Different Diagnostic Tests for Tuberculosis among People Living with HIV in Western Kenya

Joseph S Cavanaugh et al. PLoS One. .

Abstract

Background: Diagnosis followed by effective treatment of tuberculosis (TB) reduces transmission and saves lives in persons living with HIV (PLHIV). Sputum smear microscopy is widely used for diagnosis, despite limited sensitivity in PLHIV. Evidence is needed to determine the optimal diagnostic approach for these patients.

Methods: From May 2011 through June 2012, we recruited PLHIV from 15 HIV treatment centers in western Kenya. We collected up to three sputum specimens for Ziehl-Neelsen (ZN) and fluorescence microscopy (FM), GeneXpert MTB/RIF (Xpert), and culture, regardless of symptoms. We calculated the incremental yield of each test, stratifying results by CD4 cell count and specimen type; data were analyzed to account for complex sampling.

Results: From 778 enrolled patients, we identified 88 (11.3%) laboratory-confirmed TB cases. Of the 74 cases who submitted 2 specimens for microscopy and Xpert testing, ZN microscopy identified 25 (33.6%); Xpert identified those plus an additional 18 (incremental yield = 24.4%). Xpert testing of spot specimens identified 48 (57.0%) of 84 cases; whereas Xpert testing of morning specimens identified 50 (66.0%) of 76 cases. Two Xpert tests detected 22/24 (92.0%) TB cases with CD4 counts <100 cells/μL and 30/45 (67.0%) of cases with CD4 counts ≥100 cells/μl.

Conclusions: In PLHIV, Xpert substantially increased diagnostic yield compared to smear microscopy and had the highest yield when used to test morning specimens and specimens from PLHIV with CD4 count <100 cells/μL. TB programs unable to replace smear microscopy with Xpert for all symptomatic PLHIV should consider targeted replacement and using morning specimens.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Laboratory tests performed on different specimens.
Fig 2
Fig 2. Incremental Yield of Different Diagnostic Tests.
See this image and copyright information in PMC

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