Alex Telnov, Ivan Manhiça, Sekai Chenai Mathabire Rucker, Elisabeth Szumilin, Kuzani Mbendera, Helena Huerga, Loide Cossa, Mathieu Bastard, Isabel Amoros, Elisabeth Sanchez-Padilla, and Lucas Molfino
Background Current guidelines recommend the use of the lateral flow urine lipoarabinomannan assay (LAM) in HIV-positive, ambulatory patients with signs and symptoms of tuberculosis (TB) only if they are seriously ill or have CD4 count ≤ 100 cells/μl. We assessed the diagnostic yield of including LAM in TB diagnostic algorithms in HIV-positive, ambulatory patients with CD4 < 200 cells/μl, as well as the risk of mortality in LAM-positive patients who were not diagnosed using other diagnostic tools and not treated for TB. Methods and findings We conducted a prospective observational study including HIV-positive adult patients with signs and symptoms of TB and CD4 < 200 cells/μl attending 6 health facilities in Malawi and Mozambique. Patients were included consecutively from 18 September 2015 to 27 October 2016 in Malawi and from 3 December 2014 to 22 August 2016 in Mozambique. All patients had a clinical exam and LAM, chest X-ray, sputum microscopy, and Xpert MTB/RIF assay (Xpert) requested. Culture in sputum was done for a subset of patients. The diagnostic yield was defined as the proportion of patients with a positive assay result among those with laboratory-confirmed TB. For the 456 patients included in the study, the median age was 36 years (IQR 31–43) and the median CD4 count was 50 cells/μl (IQR 21–108). Forty-five percent (205/456) of the patients had laboratory-confirmed TB. The diagnostic yields of LAM, microscopy, and Xpert were 82.4% (169/205), 33.7% (69/205), and 40.0% (84/205), respectively. In total, 50.2% (103/205) of the patients with laboratory-confirmed TB were diagnosed only through LAM. Overall, the use of LAM in diagnostic algorithms increased the yield of algorithms with microscopy and with Xpert by 38.0% (78/205) and 34.6% (71/205), respectively, and, specifically among patients with CD4 100–199 cells/μl, by 27.5% (14/51) and 29.4% (15/51), respectively. LAM-positive patients not diagnosed through other tools and not treated for TB had a significantly higher risk of mortality than LAM-positive patients who received treatment (adjusted risk ratio 2.57, 95% CI 1.27–5.19, p = 0.009). Although the TB diagnostic conditions in the study sites were similar to those in other resource-limited settings, the added value of LAM may depend on the availability of microscopy or Xpert results. Conclusions LAM has diagnostic value for identifying TB in HIV-positive patients with signs and symptoms of TB and advanced immunodeficiency, including those with a CD4 count of 100–199 cells/μl. In this study, the use of LAM enabled the diagnosis of TB in half of the patients with confirmed TB disease; without LAM, these patients would have been missed. The rapid identification and treatment of TB enabled by LAM may decrease overall mortality risk for these patients., Helena Huerga and colleagues assess a urine-based lipoarabinomannan assay for diagnosing tuberculosis in immunocompromised patients with HIV., Author summary Why was this study done? Tuberculosis (TB) is the leading cause of death in HIV-positive patients, but it remains difficult to diagnose. The availability of diagnostic tests is limited, and most require sputum samples, which are difficult to obtain from very sick patients. The lipoarabinomannan assay (LAM) is a urine-based point-of-care test that has shown utility in immunosuppressed HIV-positive patients. However, this test is not widely used. Current international guidelines recommend the use of the LAM test only in extremely immunocompromised HIV-positive, ambulatory patients. However, we hypothesized that the test could also be useful to diagnose TB in a broader group including less severely immunocompromised ambulatory patients. What did the researchers do and find? We conducted a prospective observational study in 6 health facilities in Malawi and Mozambique, enrolling HIV-positive, ambulatory patients with symptoms of TB. The clinicians conducted a clinical exam, requested diagnostic tests for TB (LAM in urine, microscopy, Xpert MTB/RIF assay [Xpert], culture in sputum, and chest radiography) at the first consultation, and followed the patients at subsequent visits over a 6-month period. Of the 456 enrolled patients, 205 (45%) had TB; of these, LAM was positive in 82.4% (169/205), microscopy in 33.7% (69/205), and Xpert in 40.0% (84/205). Using LAM in addition to the other available diagnostic tools increased the proportion of patients diagnosed with TB by 38.0% compared to a diagnostic algorithm including clinical exam, chest X-ray, and microscopy, and by 34.6% compared to an algorithm including clinical exam, chest X-ray, and Xpert. A similar increase was observed for less severely immunocompromised patients. What do these findings mean? The use of the urine-based LAM test can increase the proportion of immunocompromised HIV-positive patients diagnosed with TB, including patients who are less severely immunocompromised. LAM is useful in a broader population than what it is currently recommended for, and can be expanded for use in patients who are less severely immunocompromised.