Skip Navigation LinksHome > June 1, 2014 - Volume 28 - Issue 9 > Comparative performance of urinary lipoarabinomannan assays...
AIDS:
doi: 10.1097/QAD.0000000000000264
Clinical Science

Comparative performance of urinary lipoarabinomannan assays and Xpert MTB/RIF in HIV-infected individuals

Shah, Maunanka; Ssengooba, Willyb; Armstrong, Dereka; Nakiyingi, Lydiab; Holshouser, Mollya; Ellner, Jerrold J.d; Joloba, Mosesb; Manabe, Yukari C.a,c; Dorman, Susan E.a

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Abstract

Background:

Xpert MTB/RIF (‘Xpert’) and urinary lipoarabinomannan (LAM) assays offer rapid tuberculosis (TB) diagnosis, but have suboptimal sensitivity when used individually in HIV-positive patients. The yield of these tests used in combination for the diagnosis of active TB among HIV-infected TB suspects is unknown.

Design:

Study of comparative diagnostic accuracy nested into a prospective study of HIV-infected individuals with signs and/or symptoms of TB in Uganda.

Methods:

Xpert testing of archived sputum was conducted for culture-confirmed TB cases and TB suspects in whom a diagnosis of TB was excluded. Additional testing included sputum smear microscopy, sputum culture (solid and liquid media), mycobacterial blood culture, and urinary testing for LAM using a lateral flow test (‘LF-LAM’) and an enzyme-linked immunosorbance assay (‘ELISA-LAM’).

Results:

Among 103 participants with culture-confirmed TB, sensitivity of Xpert was 76% (95% confidence interval, CI 0.66–0.84), and was superior to that of LF-LAM (49%, 95% CI 0.39–0.59, P < 0.001). Specificity was greater than 97% for both tests among 105 individuals without TB. The combination of smear microscopy and LF-LAM identified 67% (95% CI 0.57–0.76) of culture-confirmed TB cases and approached sensitivity of Xpert testing alone (P = 0.15). The sensitivity of the combination of Xpert and LF-LAM was 85% (88/103 95% CI 0.77–0.92), which was superior to either test alone (P < 0.05) and approached sensitivity of sputum liquid culture testing (94%, 95% CI 0.88–0.98, P = 0.17).

Conclusion:

Sputum Xpert and urinary LAM assays were complementary for the diagnosis of active TB in HIV-infected patients, and sensitivity of the combination of these tests was superior to that of either test alone.

© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins

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