title: Evaluation of the World Health Organization algorithm for the diagnosis of HIV-associated sputum smear-negative tuberculosis.
abstract: BACKGROUND
  Outcomes from the World Health Organization's (WHO's) recommendations for the diagnosis of smear-negative tuberculosis (SNTB) in high human immunodeficiency virus prevalence settings are unknown.
  
  
  METHODS
  We retrospectively applied the WHO algorithm for SNTB without danger signs to a prospectively enrolled cohort of ambulatory adult SNTB suspects in KwaZulu-Natal, South Africa. Participants fulfilling specified criteria for SNTB started empiric anti-tuberculosis treatment; the rest of the cohort was observed. All were followed for 8 weeks. Confirmed TB was defined as positive culture or granulomata plus acid-fast bacilli on histology.
  
  
  RESULTS
  In total, 221 participants retrospectively fulfilled the WHO ambulatory SNTB algorithm entry criteria. The diagnostic performance of the WHO algorithm was: positive predictive value 0.34 (95%CI 0.26-0.43), negative predictive value 0.86 (95%CI 0.76-0.92), positive likelihood ratio 1.43 (95%CI 1.34-1.48), negative likelihood ratio 0.46 (95%CI 0.38-0.56) and diagnostic odds 3.1 (95%CI 1.52-6.34). Losses to follow-up (n = 4), hospitalisations (n = 6) and deaths (n = 5) did not differ significantly in those who were and were not diagnosed with SNTB.
  
  
  CONCLUSIONS
  The WHO ambulatory SNTB algorithm had a reasonably high negative predictive value but low positive predictive value. Mortality over an 8-week period was low in participants who met the entry criteria for the WHO algorithm.
authors.affiliation: Department of Medicine, Edendale Hospital, Pietermaritzburg, South Africa. wilsondpk@gmail.com
authors.forename: D
authors.initials: D
authors.lastname: Wilson
authors.forename: L
authors.initials: L
authors.lastname: Mbhele
authors.forename: M
authors.initials: M
authors.lastname: Badri
authors.forename: C
authors.initials: C
authors.lastname: Morroni
authors.forename: J
authors.initials: J
authors.lastname: Nachega
authors.forename: R E
authors.initials: RE
authors.lastname: Chaisson
authors.forename: G
authors.initials: G
authors.lastname: Maartens
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D000328:Adult; D000465:Algorithms; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013019:South Africa / Q000453:epidemiology; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D014944:World Health Organization