The Value of Lateral Flow Urine Lipoarabinomannan Assay and Empirical Treatment in the Xpert MTB/RIF Ultra Era: a Prospective Cohort Study

Abstract

Introduction: The value of Lateral Flow urine Lipoarabinomannan (LF-LAM) assay and the role of empiric tuberculosis (TB) treatment in the era of the highly sensitive Xpert MTB/RIF Ultra (Xpert Ultra) assay is unclear. This study aimed to assess the additional yield of Xpert Ultra compared to Xpert MTB/RIF, the yield of LF-LAM assay when used in combination with Xpert Ultra, and the role of empiric TB treatment in the Xpert Ultra era among patients with symptoms of TB admitted to a tertiary hospital in Ethiopia. Methods: We performed a secondary analysis of a cohort of hospitalized Xpert MTB/RIF-negative patients. Sputum samples were examined for Mycobacterium tuberculosis by culture and Xpert Ultra. In HIV positive and severely ill patients, a urine sample was collected for the LF-LAM assay. Treatment outcome was assessed six months after enrollment. Logistic regression was used to identify factors predictive of deaths among Xpert Ultra negative patients. Results: Of the 250 hospitalized Xpert MTB/RIF-negative patients, 35 (14.0%) had culture-confirmed TB. The Xpert Ultra assay diagnosed 31 of the 35 culture positive cases that had been missed by Xpert MTB/RIF. The LF-LAM assay did not identify any case that was not detected by Xpert Ultra. Empiric treatment did not improve survival among Xpert Ultra negative patients (OR 1.28, 95% CI: 0.3-5.3). Low body mass index (< 18.5kg/m2) was the only significant predictor of death in Xpert Ultra negative patients (OR 4.0, 95% CI: 1.12-16.5).Conclusions: In this prospective cohort, we observed that LF-LAM did not improve the diagnostic yield when used in combination with Xpert Ultra and did not find a survival benefit of empiric treatment among Xpert Ultra negative individuals. Research is needed to determine the optimal management of patients with presumptive TB and a negative Xpert Ultra assay in high TB burden settings.

GeneXpert has perfect test agreement with WHO recommended TB lipoarabinomannan antigen test for the diagnosis of TB among under five children from urine sample in Tuberculosis endemic setting of Ethiopia

“…[29], Zambia 1.58% [29], Mozambique 1.65% [30], south Africa 1.3% [31] and Tanzania 5.4% [42]. In opposite, lower prevalence was detected than other reports from Jimma, Ethiopia 11.5% [33], other study of India 20% [34], Nigeria 32% [35] and Bangladesh 32.97% [36]. The variation in the prevalence of Pediatric TB could be due to the difference in socio-demographic characteristics, HIV status of study participants.…”