Department of Hepatology, Imperial College London, St Mary's Hospital, London, UK.
Department of Psychiatry, Muhimbili University of Health and Allied Sciences, Muhimbili National Hospital, Dar es Salaam, Tanzania.
J Int AIDS Soc. 2017 Sep 19;20(1):21856. doi: 10.7448/IAS.20.1.21856.
A lack of access to hepatitis C virus (HCV) diagnostics is a significant barrier to achieving the World Health Organization 2030 global elimination goal. HCV core antigen (HCVcAg) quantification and dried blood spot (DBS) are appealing alternatives to conventional HCV serology and nucleic acid testing (NAT) for resource-constraint settings, particularly in difficult-to-reach populations. We assessed the accuracy of serum and DBS HCVcAg testing in people who inject drugs in Tanzania using HCV NAT as a reference.
Between May and July 2015, consecutive HCV-seropositive patients enrolled in the local opioid substitution treatment centre were invited to participate in the study. All had HCV RNA detection (Roche Molecular Systems, Pleasanton, CA, USA), genotyping (NS5B gene phylogenetic analysis) and HCVcAg on blood samples and DBS (Architect assay; Abbott Diagnostics, Chicago, IL, USA).
Out of 153 HCV-seropositive individuals, 65 (42.5%) and 15 (9.8%) were co-infected with HIV (41 (63%) were on anti-retroviral therapy (ARVs)) and hepatitis B respectively. In total, 116 were viraemic, median viral load of 5.7 (Interquartile range (IQR); 4.0-6.3) log iU/ml (75 (68.2%) were genotype 1a, 35 (31.8%) genotype 4a). The median alanine transaminase (ALT) (iU/l), aspartate transaminase (AST) (iU/l) and gamma-glutamyl transferase (GGT) (iU/l) were 35 (IQR; 23-51), 46 (32-57) and 69 (35-151) respectively. For the quantification of HCV RNA, serum HCVcAg had a sensitivity at 99.1% and a specificity at 94.1%, with an area under the receiver operating curve (AUROC) at 0.99 (95% CI 0.98-1.00). DBS HCVcAg had a sensitivity of 76.1% and a specificity of 97.3%, with an AUROC of 0.87 (95% CI 0.83-0.92). HCVcAg performance did not differ by HIV co-infection or HCV genotype. Our study suggests that HCVcAg testing in serum is an excellent alternative to HCV polymerase chain reaction in Africa. Although HCVcAg detection and quantification in DBS has a reduced sensitivity, its specificity and accuracy are good and it could therefore be used for scaling up HCV testing and care in resource-limited African settings.
缺乏丙型肝炎病毒 (HCV) 诊断是实现世界卫生组织 2030 年全球消除目标的一个重大障碍。HCV 核心抗原 (HCVcAg) 定量和干血斑 (DBS) 是对资源有限环境中常规 HCV 血清学和核酸检测 (NAT) 的有吸引力的替代方法，特别是在难以到达的人群中。我们使用 HCV NAT 作为参考，评估了坦桑尼亚注射毒品者的血清和 DBS HCVcAg 检测的准确性。
2015 年 5 月至 7 月期间，当地阿片类药物替代治疗中心连续招募了 HCV 血清阳性的患者参与该研究。所有患者均进行 HCV RNA 检测（罗氏分子系统公司，普莱斯顿，加利福尼亚州，美国）、基因分型（NS5B 基因系统进化分析）和血液样本及 DBS（Architect 检测；雅培诊断公司，芝加哥，伊利诺伊州，美国）的 HCVcAg 检测。
在 153 名 HCV 血清阳性个体中，65 名（42.5%）和 15 名（9.8%）同时感染了 HIV（41 名（63%）正在接受抗逆转录病毒治疗（ARVs））和乙型肝炎。共有 116 名病毒血症患者，中位病毒载量为 5.7（四分位间距 (IQR); 4.0-6.3) log iU/ml（75 名（68.2%）为基因型 1a，35 名（31.8%）为基因型 4a）。中位丙氨酸转氨酶 (ALT)（IU/L）、天冬氨酸转氨酶 (AST)（IU/L）和γ-谷氨酰转移酶 (GGT)（IU/L）分别为 35（IQR；23-51）、46（32-57）和 69（35-151）。对于 HCV RNA 的定量，血清 HCVcAg 的灵敏度为 99.1%，特异性为 94.1%，受体操作特征曲线 (AUROC) 下面积为 0.99（95%CI 0.98-1.00）。DBS HCVcAg 的灵敏度为 76.1%，特异性为 97.3%，AUROC 为 0.87（95%CI 0.83-0.92）。HCVcAg 检测的性能不受 HIV 合并感染或 HCV 基因型的影响。我们的研究表明，HCVcAg 检测在血清中是非洲 HCV 聚合酶链反应的极好替代方法。虽然 DBS 中 HCVcAg 的检测和定量敏感性降低，但特异性和准确性良好，因此可用于扩大资源有限的非洲环境中的 HCV 检测和护理。
