title: Comparative Yield of Different Diagnostic Tests for Tuberculosis among People Living with HIV in Western Kenya.
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.
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Cavanaugh
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Surbhi
authors.initials: S
authors.lastname: Modi
authors.affiliation: Kenya Medical Research Institute (KEMRI) Center for Global Health Research, Kisumu, Kenya.
authors.forename: Susan
authors.initials: S
authors.lastname: Musau
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Kimberly
authors.initials: K
authors.lastname: McCarthy
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Heather
authors.initials: H
authors.lastname: Alexander
authors.affiliation: Kenya Medical Research Institute (KEMRI) Center for Global Health Research, Kisumu, Kenya.
authors.forename: Barbara
authors.initials: B
authors.lastname: Burmen
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Charles M
authors.initials: CM
authors.lastname: Heilig
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Ray W
authors.initials: RW
authors.lastname: Shiraishi
authors.affiliation: United States Centers for Disease Control and Prevention, Kisumu, Kenya.
authors.forename: Kevin
authors.initials: K
authors.lastname: Cain
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count; D003710:Demography; D003955:Diagnostic Tests, Routine; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000276:immunology; D006801:Humans; D007630:Kenya; D008297:Male; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000150:complications* / Q000175:diagnosis*; D055815:Young Adult