ABSTRACT
OBJECTIVE: To assess the diagnostic performance of urine lipoarabinomannan (LAM) detection for TB screening in HIV-positive adults in Ethiopia. METHODS: Testing for LAM was performed using the Determine TB-LAM lateral flow assay on urine samples from participants in a prospective cohort with baseline bacteriological categorisation for active TB in sputum. Characteristics of TB patients with regard to LAM status were determined. Participants were followed for 6 months to evaluate survival, retention in care and incident TB. RESULTS: Positive LAM results were found in 78/757 participants. Among 128 subjects with definite (confirmed by culture and/or Xpert MTB/RIF) TB, 33 were LAM-positive (25.8%); the respective figure for clinically diagnosed cases was 2/20 (10%). Five of the remaining 43 LAM-positive individuals had died during the 6-month follow-up period, whereas 38 remained in care without clinical signs of TB. The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 25.8%, 92.9%, 42.3% and 86.0%, respectively. Among TB patients, LAM positivity was associated with higher WHO clinical stage, lower body mass index (BMI), CD4 cell and haemoglobin levels, and with increased mortality. A combination algorithm of urine LAM testing and sputum smear microscopy detected 49 (38.2%) of definite TB cases; among those with CD4 count ≤100 cells/mm3 , this proportion was 66.7%. CONCLUSIONS: The performance of urine LAM testing for TB detection was poor in this population. However, this was improved among subjects with CD4 count ≤100 cells/mm3 . In combination with sputum microscopy urine, LAM could be considered for targeted TB screening in this subgroup.
ABSTRACT
BACKGROUND: Currently, antiretroviral therapy (ART) is recommended for all HIV-positive patients with tuberculosis (TB). The timing of ART during the course of anti-TB treatment is based on CD4 cell counts. Access to CD4 cell testing is not universally available; this constitutes an obstacle for the provision of ART in low-income countries. OBJECTIVE: To determine clinical variables associated with HIV co-infection in TB patients and to identify correlations between clinical variables and CD4 cell strata in HIV/TB co-infected subjects, with the aim of developing a clinical scoring system for the assessment of immunosuppression. DESIGN: Cross-sectional study of adults with TB (with and without HIV co-infection) recruited in Ethiopian outpatient clinics. Clinical variables potentially associated with immunosuppression were recorded using a structured questionnaire, and they were correlated to CD4 cell strata used to determine timing of ART initiation. Variables found to be significant in multivariate analysis were used to construct a scoring system. Results : Among 1,116 participants, the following findings were significantly more frequent in 307 HIV-positive patients compared to 809 HIV-negative subjects: diarrhea, odynophagia, conjunctival pallor, herpes zoster, oral candidiasis, skin rash, and mid-upper arm circumference (MUAC) <20 cm. Among HIV-positive patients, conjunctival pallor, MUAC <20 cm, dyspnea, oral hairy leukoplakia (OHL), oral candidiasis, and gingivitis were significantly associated with <350 CD4 cells/mm(3). A scoring system based on these variables had a negative predictive value of 87% for excluding subjects with CD4 cell counts <100 cells/mm(3); however, the positive predictive value for identifying such individuals was low (47%). CONCLUSIONS: Clinical variables correlate with CD4 cell strata in HIV-positive patients with TB. The clinical scoring system had adequate negative predictive value for excluding severe immunosuppression. Clinical scoring systems could be of use to categorize TB/HIV co-infected patients with regard to the timing of ART initiation in settings with limited access to laboratory facilities.
