The results for unselected patients were 31 and 62% respectively. Pooled sensitivities were 29% in outpatients with TB symptoms and 52% in hospitalised patients with TB symptoms. reported pooled sensitivities of 42% in patients with TB symptoms as opposed to 35% in patients who had not been assessed for features of TB with corresponding specificities of 91 and 95% respectively. In a recent Cochrane review of the performance of TB LAM in HIV positive patients, Bjerrum et al. The reported sensitivity and specificity of TB LAM varies according to the cohort studied: in particular whether the patients had TB symptoms or were an unselected cohort whether the participants were outpatients or were hospitalised and according to CD4 lymphocyte count. Furthermore, patients with extrapulmonary TB may have negative sputum and endotracheal aspirates using GeneXpert but may have LAM antigenuria which the TB LAM Ag test could detect. The advantage of the TB LAM Ag test is that it can be done at the patient’s bedside and results are available immediately. The Alere Determine TB LAM Ag test is a simple, easy to use lateral flow assay. The precise mechanism by which LAM gets into the urine is unknown. LAM is one of the lipopolysaccharides that make up the mycobacterial cell wall. Many mycobacterial antigens can be detected in urine, of which the most promising has been the cell wall lipopolysaccharide lipoarabinomannan (LAM). Urine antigen testing is an attractive option for diagnosis of TB as it is an easily obtained specimen and does not generate dangerous aerosols. The ideal test would thus also be point of care and would deliver an answer at the bedside. Delays in diagnosis and initiation of treatment result in higher mortality rates. A diagnostic test for TB would ideally be able to detect pulmonary and extrapulmonary TB and perform well in both HIV positive and negative patients. The sensitivity of GeneXpert is lower, and the risk of extrapulmonary TB is higher, in HIV positive patients. GeneXpert has the greatest utility for diagnosis of pulmonary TB and may have lower sensitivity or may not be technically feasible for diagnosis of extrapulmonary TB. The GeneXpert is an automated platform that offers a more rapid test but still requires sophisticated equipment and a laboratory to process the specimen. Culture can take up to 6 weeks and more rapid tests are needed for critically ill patients in an intensive care setting. The gold standard for TB diagnosis is culture of pulmonary or extrapulmonary specimens. The mortality rate of TB which necessitates intensive care unit (ICU) admission ranges between 15.5 and 65.9%. Tuberculosis (TB) is a major contributor to mortality globally. A positive urinary LAM should prompt consideration to initiate antituberculous treatment while the results of further diagnostic testing are awaited. Urinary LAM allows for rapid bedside diagnosis of tuberculosis in critically ill patients. Urinary LAM had a sensitivity of 50.0% (95% CI, 21.1 to 78.9%) and a specificity of 84.2% (95% CI, 68.8 to 94.0%) for confirmed tuberculosis. ![]() All patients received mechanical ventilation, and the ICU mortality was 60%. ![]() ![]() Resultsįifty patients were included in the study, with 12 having confirmed tuberculosis. A patient was classified as having confirmed tuberculosis if they met the following criteria: a clinical presentation compatible with tuberculosis, with either a positive TB culture, a positive GeneXpert, or a histological diagnosis of tuberculosis. Urinary LAM testing was performed using the Alere Determine TB LAM Ag lateral flow assay test strips. The study was a single centre, prospective observational study that compared the utility of urinary LAM with conventional tuberculosis diagnostic modalities in patients with suspected tuberculosis who required intensive care admission. Urinary LAM may be used as a bedside diagnostic test for tuberculosis. Lipoarabinomannan (LAM) is a lipopolysaccharide found in the cell wall of Mycobacterium tuberculosis. Patients with tuberculosis who require critical care have a high mortality and delay in initiating antituberculous therapy is associated with increased mortality. Tuberculosis is a major global public health concern.
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