Novel High Sensitivity Tuberculosis Point-of-Care Test for People Living with HIV

Abstract

Background: Most tuberculosis-related deaths in people living with HIV (PLHIV) could be prevented with earlier diagnosis and treatment. The only commercially available tuberculosis point-of-care test (Alere DetermineTM TB LAM Ag (AlereLAM)) has suboptimal sensitivity which restricts its use in clinical practice. The novel Fujifilm SILVAMP TB LAM (FujiLAM) test was designed to achieve superior diagnostic accuracy. Methods: We performed a blinded assessment of FujiLAM on biobanked urine samples from three independent prospective cohort studies of hospitalized PLHIV at two South African district hospitals. Diagnostic accuracy was determined against both microbiological (MRS) and composite reference standards (CRS, including clinical diagnoses), in comparison with AlereLAM. Findings: A total of 968 newly admitted PLHIV were included. The prevalence of microbiologically-confirmed TB was 62% and the median CD4 count 86 cells/µl. In a meta-analysis, the estimated sensitivity of the FujiLAM was superior at 70·4% (95%CI: 53·0-83·1) over that of AlereLAM at 42·3% (31·7-51·8), against the MRS, with a difference of 28.1% (21.5-34.4). Specificities were 90·8% (86·0-94·4) and 95·0% (87·7-98·8) for the FujiLAM and AlereLAM against the MRS, respectively, with a non-significant difference of -4.2% (-12.7-4.4). Against the CRS, specificities of both assays were higher (FujiLAM 95·7% and AlereLAM 98·2%) but sensitivities were lower (FujiLAM 64·9% and AlereLAM 38·2%). In the subgroup of patients with CD4 ≤100 cells/µl, the sensitivity of FujiLAM was 84·2% (71·4-91·4) versus 57·3% (42·2-69·6) for AlereLAM. Interpretation: In comparison to AlereLAM, FujiLAM offers superior diagnostic sensitivity, while maintaining specificity, and has the potential to transform rapid point-of-care tuberculosis diagnosis for hospitalized PLHIV. FujiLAM's suitability for settings of intended use needs to be assessed in a prospective evaluation. Funding: GHIT Fund, UK DFID, Dutch MoFA, BMGF, Australian DFAT, German BMBF through KfW, Wellcome Trust, DST/ NRF of South Africa, and South African MRC. Declaration of Interest: TB, EI, AM, SO, CCB, and CMD are 384 employed by FIND. FIND is a not for-profit foundation that supports the evaluation of publicly prioritized tuberculosis assays and the implementation of WHO-approved (guidance and prequalification) assays using donor grants. FIND has product evaluation agreements with several private sector companies that design diagnostics for tuberculosis and other diseases. These agreements strictly define FIND’s independence and neutrality vis-a-vis the companies whose products get evaluated and describe roles and responsibilities. AP and TB report patents in the field of lipoarabinomannan detection. All other authors declare no competing interests. Ethical Approval: All study-related activities were approved by the Human Research Ethics Committee (HREC) of the University of Cape Town (UCT). Written informed consent was obtained from patients, as per study protocols. Study participation did not affect standard of care. Reporting followed STARD guidelines.12 167 Retrospective urine LAM testing was supervised by the sponsor, FIND, and was performed at UCT in April 2018.