2 research outputs found
Early morning urine collection to improve the sensitivity of LAM in hospitalised TB/HIV co-infected patients
Point-of-care detection of urine lipoarabinomannan (LAM) is a low-cost rapid TB diagnostic for use in HIV co-infected patients. However, its sensitivity in these patients is suboptimal. Strategies to improve its performance is a need. The hypothesis was that early morning urine (EMU), rather than random urine sampling, would improve LAM's sensitivity. Methods Recruitment process conducted between June 2012 and February 2014 for HIV-infected patients from four hospitals in Cape Town, South Africa presenting with possible TB (all patients initiated on TB treatment). Fresh random and early morning urine (EMU) samples (~10-30 ml) collected in sterile containers. Following the manufacturer's instructions, an Alere Determine® TB Lateral flow assay performed on each sample, using both grade 1 and 2 cut-points. A single sputum Xpert MTB/RIF and/or liquid TB culture was a reference standard. Those designated probable TB patients were sputum Xpert MTB/RIF and/ TB culture negative, but started on TB treatment
Comparison of same day diagnostic tools including Gene Xpert and unstimulated IFN-γ for the evaluation of pleural tuberculosis: a prospective cohort study
Background: The accuracy of currently available same-day diagnostic tools (smear microscopy and conventional nucleic acid amplification tests) for pleural tuberculosis (TB) is sub-optimal. Newer technologies may offer improved detection. Methods: Smear-microscopy, adenosine deaminase (ADA), interferon gamma (IFN-γ), and Xpert MTB/RIF [using an unprocessed (1 ml) and centrifuged (~20 ml) sample] test accuracy was evaluated in pleural fluid from 103 consecutive patients with suspected pleural TB. Culture for M.tuberculosis and/or histopathology (pleural biopsy) served as the reference standard. Patients were followed prospectively to determine their diagnostic categorisation. Results: Of 93 evaluable participants, 40 had definite-TB (reference positive), 5 probable-TB (not definite but treated for TB) and 48 non-TB (culture and histology negative, and not treated for TB). Xpert MTB/RIF sensitivity and specificity (95% CI) was 22.5% (12.4 - 37.6) and 98% (89.2 - 99.7), respectively, and centrifugation did not improve sensitivity (23.7%). The Xpert MTB/RIF internal positive control showed no evidence of inhibition. Biomarker specific sensitivity, specificity, PPV, and NPVs were: ADA (48.85 IU/L; rule-in cut-point) 55.3% (39.8 - 69.9), 95.2% (83.9 - 98.7), 91.4 (73.4 - 95.4), 69.7% (56.7 - 80.1); ADA (30 IU/L; clinically used cut-point) 79% (63.7 - 89), 92.7% (80.6 - 97.5), 91.0 (73.4 - 95.4), 82.7% (69.3 - 90.1); and IFN-γ (107.7 pg/ml; rule-in cut-point) 92.5% (80.2 - 97.5), 95.9% (86.1 - 98.9), 94.9% (83.2 - 98.6), 93.9% (83.5 - 97.9), respectively (IFN-γ sensitivity and NPV better than Xpert [p < 0.05] and rule-in ADA [p < 0.05]). Conclusion: The usefulness of Xpert MTB/RIF to diagnose pleural TB is limited by its poor sensitivity. IFN-γ is an excellent rule-in test and, compared to ADA, has significantly better sensitivity and rule-out value in a TB-endemic setting