Abstract
BackgroundThe 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.Methods281 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.Results187/281 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.ConclusionsLAM 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.
Highlights
The early high mortality (.25%) amongst hospitalised TB HIV co-infected patients in resource-poor settings requires urgent attention [1,2]
Formalized World Health Organisation (WHO) clinical algorithms are available to guide empiric treatment and, despite modest diagnostic accuracy in ambulatory patients [9,10], evidence suggests that their use may reduce mortality amongst hospitalised HIV-infected patients [8]
Our study investigated whether point-of-care urine LAM strip testing offered any value over basic clinical and radiological screening, and whether testing was redundant in the context of routine ‘real world’ day-to-day clinical practice where empiric treatment is commonly used
Summary
The early high mortality (.25%) amongst hospitalised TB HIV co-infected patients in resource-poor settings requires urgent attention [1,2]. Empiric TB treatment, based only on clinical and radiological findings is common (,50%) amongst hospitalised HIV-infected patients with advanced immunosuppression; given their high pre-test probability of disease and illness severity [7,8]. Formalized World Health Organisation (WHO) clinical algorithms are available to guide empiric treatment and, despite modest diagnostic accuracy in ambulatory patients [9,10], evidence suggests that their use may reduce mortality amongst hospitalised HIV-infected patients [8]. Given high rates of empiric treatment amongst hospitalised patients in highburden 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
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