title: The role of macroscopic sputum quality assessments to optimise sputum testing for tuberculosis.
abstract: METHODS
  Community-wide active case finding for tuberculosis (TB) using Xpert® MTB/RIF as the primary screening tool, Ca Mau Province, Viet Nam.
  
  
  OBJECTIVE
  To determine whether macroscopic sputum quality characteristics (sputum colour and volume) can be used to predict Xpert MTB-negative sputum and hence exclude sputum samples from testing.
  
  
  METHODS
  Field staff conducted household visits to approximately 51,200 adults in 58 villages randomly selected from throughout the province. Sputum samples from all screened participants who were able to produce ⩾1 ml sputum underwent macroscopic sputum assessment and were tested with Xpert.
  
  
  RESULTS
  Of the 21,624 sputum samples tested, 159 (0.74%) were Xpert MTB-positive; 93% of the samples were 1-2 ml and nearly all were mucoid (93%) or mucopurulent (5.7%). One salivary sample was Xpert MTB-positive (2.0% of all salivary samples). The lowest positive predictive value for any sputum volume or colour characteristic was 0.66%. This was not substantially different from the overall prevalence of positive sputum Xpert MTB (0.74%).
  
  
  CONCLUSIONS
  Sputum colour and volume cannot be used to predict the presence or absence of M. tuberculosis in sputum detected using Xpert. These sputum quality parameters cannot therefore be used to exclude sputum samples from testing for TB.
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam; South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia. jennifer.ho@sydney.edu.au.
authors.forename: J
authors.initials: J
authors.lastname: Ho
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam.
authors.forename: P T B
authors.initials: PT
authors.lastname: Nguyen
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam.
authors.forename: T A
authors.initials: TA
authors.lastname: Nguyen
authors.affiliation: Ca Mau Centre for Social Disease Prevention, Ca Mau, Viet Nam.
authors.forename: H K
authors.initials: HK
authors.lastname: Tran
authors.affiliation: Ca Mau Centre for Social Disease Prevention, Ca Mau, Viet Nam.
authors.forename: V S
authors.initials: VS
authors.lastname: Nguyen
authors.affiliation: National Tuberculosis Programme, Hanoi, Viet Nam.
authors.forename: N V
authors.initials: NV
authors.lastname: Nhung
authors.affiliation: Centre for Operational Research, International Union Against Tuberculosis and Lung Disease, Paris, France.
authors.forename: N B
authors.initials: NB
authors.lastname: Hoa
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam.
authors.forename: T N
authors.initials: TN
authors.lastname: Phong
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam.
authors.forename: B K
authors.initials: BK
authors.lastname: Luu
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam.
authors.forename: T M H
authors.initials: TM
authors.lastname: Nguyen
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam; Department of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada.
authors.forename: G J
authors.initials: GJ
authors.lastname: Fox
authors.affiliation: Woolcock Institute of Medical Research, Hanoi, Viet Nam; South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: G B
authors.initials: GB
authors.lastname: Marks
mesh_terms: D000293:Adolescent; D000328:Adult; D003955:Diagnostic Tests, Routine / Q000592:standards*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014376:Tuberculosis / Q000175:diagnosis*; D014744:Vietnam; D055815:Young Adult