WHO policy guidance: The use of lateral flow urine lipoarabinomannan assay (LF-LAM) for the diagnosis and screening of active TB in people living with HIV
The World Health Organization (WHO) has evaluated a new diagnostic test - Alere DetermineTM - a urine lateral flow lipoarabinomannan assay (LF-LAM,) to determine its suitability for use in the screening or diagnosis of tuberculosis disease.
Lipoarabinomannan (LAM) is a substance present in the cell walls of TB bacteria which is released from bacterial cells that are either alive or dead. LAM appears to be present only in people with active TB disease. Tests based on the detection of LAM in urine have the potential to be point-of-care tests for TB. The main advantages over sputum-based testing are that urine is easy to collect and store, and lacks the infection control risks associated with sputum collection.
WHO review and recommendations
In June 2015, WHO convened a Guideline Development Group to review the evidence on the use of the urine-based assay (manufactured by Alere Incorporated in the USA) for the detection of TB in people living with HIV.
Evidence from a systematic review of the performance characteristics of the assay was assessed by the Guideline Development Group. Based on their findings, WHO has now published guidance on the test for which certain patient groups could benefit.
The test is not recommended by WHO for TB screening or diagnosis of active TB disease in most population groups. However, it is recommended to assist the diagnosis of TB in two specific population groups: in HIV positive adult in-patients with signs and symptoms of TB (pulmonary and/or extrapulmonary) and a CD4 cell count less than or equal to 100 cells/μL, and people living with HIV who are deemed “seriously ill” under given criteria, given their high risk for mortality, regardless of CD4 count or if the CD4 count is unknown.
Full details of evidence evaluated, definitions for the two populations groups that may benefit from the test and WHO policy recommendations are available at: http://apps.who.int/iris/bitstream/10665/193633/1/9789241509633_eng.pdf?ua=1
The assay reviewed is a commercially available test to detect active TB (Alere DetermineTM TB LAM Ag, Alere Inc, Waltham, MA, USA). The evidence reviewed and this policy guidance apply to the use of this commercial LF-LAM assay only. Other LAM based assays have not been adequately validated or used outside limited research settings. Any new or generic LAM-based assay would be subject to adequate evaluation and validation in the settings of intended use as per WHO policy.
These recommendations will be incorporated into the upcoming WHO consolidated guideline for people living with HIV.
Download the policy guidance here.
