TY - JOUR T1 - Suboptimal specificity of Xpert MTB/RIF among treatment-experienced patients JF - European Respiratory Journal JO - Eur Respir J SP - 1504 LP - 1506 DO - 10.1183/09031936.00214114 VL - 45 IS - 5 AU - John Z. Metcalfe AU - Salome Makumbirofa AU - Beauty Makamure AU - Reggie Mutetwa AU - Renée A. Peñaloza AU - Charles Sandy AU - Wilbert Bara AU - Stanley Mungofa AU - Philip C. Hopewell AU - Peter Mason Y1 - 2015/05/01 UR - http://erj.ersjournals.com/content/45/5/1504.abstract N2 - The Xpert MTB/RIF assay (Cepheid, Sunnyvale, CA, USA) is strongly recommended by the World Health Organization as an initial diagnostic test for treatment-experienced patients of any retreatment category [1–3]. Yet, retreatment tuberculosis (TB) suspects have been infrequently included in studies of Xpert [4], probably because current-generation PCR-based tests are unable to determine Mycobacterium tuberculosis viability [5]. Indeed, Xpert is known to frequently remain positive at the end of standard short-course therapy [6], with case reports emerging of Xpert false-positivity for up to 5 years post-treatment completion [7, 8]. Furthermore, 56% (n=3485/6285) of specificity data informing the most recent Cochrane meta-analysis [4] was derived from validation and demonstration studies [9, 10], which may be optimistic due to selection bias related to post-enrolment exclusions [7]. Not surprisingly, there have been increasing calls to clarify the guidelines for use of Xpert among treatment-experienced patients [11]. Xpert false-positivity may be common in recurrent TB. High Xpert quantitation result is unlikely to be false-positive http://ow.ly/Ilg0F We would like to thank Harare City Health Department (Harare, Zimbabwe) clinicians and staff for their support and assistance. ER -