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Background: We evaluated the field performance of a rapid point-of-care (POC) test for hepatitis B surface antigen (HBsAg) that could support decentralization and scale-up of hepatitis B virus (HBV) diagnosis in Africa., Objective: To determine the field performance of the Determine HBsAg POC test for diagnosis of HBV co-infection among HIV patients in Zambia., Study Design: Between 2013-2014, we screened HIV-infected adults for HBsAg at two urban clinics in Zambia. A subset were tested with the POC Determine HBsAg (Alere, USA) by finger prick in the clinic and HBsAg serology (Access2Analyzer, Beckman Coulter) at a reference laboratory. If either test was reactive, we determined HBV viral load (VL) and genotype. We described patient demographic and clinical characteristics (including liver fibrosis) and assessed the sensitivity, specificity, positive and negative predictive values (PPV and NPV) of the Determine test. In secondary analyses, we assessed sensitivity among patients with replicating HBV (i.e., VL>20 IU/ml) and with high HBV VL (i.e.,>20,000IU/ml)., Results: Among 412 participants with both HBsAg tests, median age was 34 years, 51% were women, and median CD4 was 208 cells/mm 3 . By serology, 66 (16%) were HBsAg-positive. Overall Determine had 87.9% sensitivity, 99.7% specificity, 98.3% PPV, and 97.7% NPV. Six of 8 patients with false negative results had undetectable HBV VL and no evidence of significant liver fibrosis. Test sensitivity was 95.9% among the 51 with replicating HBV and 100% among the 28 with high HBV VL., Conclusions: Determine HBsAg is a cheaper alternative HBV testing option compared to the gold standard ELISA and has high specificity and good sensitivity in the field among HIV-infected individuals., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Access to hepatitis B viral load (VL) testing is poor in sub-Saharan Africa (SSA) due to economic and logistical reasons., Objectives: To demonstrate the feasibility of testing dried blood spots (DBS) for hepatitis B virus (HBV) VL in a laboratory in Lusaka, Zambia, and to compare HBV VLs between DBS and plasma samples., Study Design: Paired plasma and DBS samples from HIV-HBV co-infected Zambian adults were analyzed for HBV VL using the COBAS AmpliPrep/COBAS TaqMan HBV test (Version 2.0) and for HBV genotype by direct sequencing. We used Bland-Altman analysis to compare VLs between sample types and by genotype. Logistic regression analysis was conducted to assess the probability of an undetectable DBS result by plasma VL., Results: Among 68 participants, median age was 34 years, 61.8% were men, and median plasma HBV VL was 3.98logIU/ml (interquartile range, 2.04-5.95). Among sequenced viruses, 28 were genotype A1 and 27 were genotype E. Bland-Altman plots suggested strong agreement between DBS and plasma VLs. DBS VLs were on average 1.59logIU/ml lower than plasma with 95% limits of agreement of -2.40 to -0.83log IU/ml. At a plasma VL ≥2,000IU/ml, the probability of an undetectable DBS result was 1.8% (95% CI: 0.5-6.6). At plasma VL ≥20,000IU/ml this probability reduced to 0.2% (95% CI: 0.03-1.7)., Conclusions: In a Zambian laboratory, we observed strong agreement between DBS and plasma VLs and high sensitivity in DBS at plasma VL ≥2,000IU/ml. As HBV treatment expands, DBS could increase access to HBV VL testing and care in SSA settings., (Copyright © 2015. Published by Elsevier B.V.)