title: Can point-of-care urine LAM strip testing for tuberculosis add value to clinical decision making in hospitalised HIV-infected persons?
abstract: BACKGROUND
  The urine lipoarabinomannan (LAM) strip-test (Determine®-TB) can rapidly rule-in TB in HIV-infected persons with advanced immunosuppression. However, given high rates of empiric treatment amongst hospitalised patients in high-burden settings (≈ 50%) it is unclear whether LAM can add any value to clinical decision making, or identify a subset of patients with unfavourable outcomes that would otherwise have been missed by empiric treatment.
  
  
  METHODS
  281 HIV-infected hospitalised patients with suspected TB received urine LAM strip testing, and were categorised as definite (culture-positive), probable-, or non-TB. Both the proportion and morbidity of TB cases identified by LAM testing, early empiric treatment (initiated prior to test result availability) and a set of clinical predictors were compared across groups.
  
  
  RESULTS
  187/281 patients had either definite- (n = 116) or probable-TB (n = 71). As a rule-in test for definite and probable-TB, LAM identified a similar proportion of TB cases compared to early empiric treatment (85/187 vs. 93/187, p = 0.4), but a greater proportion than classified by a set of clinical predictors alone (19/187; p<0.001). Thirty-nine of the 187 (21%) LAM-positive patients who had either definite- or probable-TB were missed by early empiric treatment, and of these 25/39 (64%) would also have been missed by smear microscopy. Thus, 25/187 (8%) of definite- or probable-TB patients with otherwise delayed initiation of TB treatment could be detected by the LAM strip test. LAM-positive patients missed by early empiric treatment had a lower median CD4 count (p = 0.008), a higher median illness severity score (p = 0.001) and increased urea levels (p = 0.002) compared to LAM-negative patients given early empiric treatment.
  
  
  CONCLUSIONS
  LAM strip testing outperformed TB diagnosis based on clinical criteria but in day-to-day practice identified a similar proportion of patients compared to early empiric treatment. However, compared to empiric treatment, LAM identified a different subset of patients with more advanced immunosuppression and greater disease severity.
authors: Lung Infection and Immunity Unit, Division of Pulmonology & UCT Lung Institute, Department of Medicine, University of Cape Town, Cape Town, South Africa.
authors: Jonathan G
authors: JG
authors: Peter
authors: Grant
authors: G
authors: Theron
authors: Keertan
authors: K
authors: Dheda
mesh_terms: D000328:Adult; D060085:Coinfection; D005260:Female; D006678:HIV / Q000302:isolation & purification; D015658:HIV Infections / Q000652:urine / Q000821:virology*; D006801:Humans; D008070:Lipopolysaccharides / Q000652:urine*; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D019095:Point-of-Care Systems; D011934:Reagent Strips; D012720:Severity of Illness Index; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology / Q000652:urine*; D016482:Urinalysis / Q000706:statistics & numerical data*
chemical_list: D008070:Lipopolysaccharides; D011934:Reagent Strips; C050016:lipoarabinomannan
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