Point of care and oral fluid hepatitis B testing in remote Indigenous communities of northern Australia

Abstract

Many Indigenous Australians in northern Australia living with chronic hepatitis B are unaware of their diagnosis due to low screening rates. A venous blood point of care test (POCT) or oral fluid laboratory test could improve testing uptake in this region. The purpose of this study was to assess the field performance of venous blood POCT and laboratory performance of an oral fluid hepatitis B surface antigen (HBsAg) test in Indigenous individuals living in remote northern Australian communities. The study was conducted with four very remote communities in the tropical north of Australia's Northern Territory. Community research workers collected venous blood and oral fluid samples. We performed the venous blood POCT for HBsAg in the field. We assessed the venous blood and oral fluid specimens for the presence of HBsAg using standard laboratory assays. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the POCT and oral fluid test, using serum laboratory detection of HBsAg as the gold standard. From 215 enrolled participants, 155 POCT and 197 oral fluid tests had corresponding serum HBsAg results. The POCT had a sensitivity of 91.7% and specificity of 100%. Based on a population prevalence of 6%, the PPV was 100% and NPV was 99.5%. The oral fluid test had a sensitivity of 56.8%, specificity of 98.1%, PPV of 97.3% and NPV of 65.9%. The venous blood POCT has excellent test characteristics and could be used to identify individuals with chronic HBV infection in high prevalence communities with limited access to health care. Oral fluid performance was suboptimal.

Point-of-Care Tests for Hepatitis B: An Overview

“…The cause of the reported lower sensitivity in HIV-coinfected populations [ 39 , 40 , 43 , 44 ] is unclear, but potential reasons may include the cross reaction of HIV-reverse transcriptase inhibitors and hepatitis B virus, a higher rate of occult hepatitis B infection in early HIV cohorts, a higher reported rate of HBsAg loss in both untreated and treated HIV-infected populations and the use of tenofovir-based HIV regimens that effectively suppress hepatitis B virus DNA levels and a large decline in HBsAg titres [ 31 , 45 , 46 ]. SD Bioline HBsAg [ 38 , 47 , 48 , 49 ] and VIKIA HBsAg POC test [ 32 , 33 , 38 , 50 , 51 ] have also been shown to have good sensitivity (above 90%) and excellent specificity (above 99%) in general populations; however, lower sensitivity was also reported in HIV-infected populations [ 40 ].…”

“…Innovations in sampling technique have provided more convenient specimen collection methods, such as using oral fluid as specimen collected by an oral swab [ 25 , 48 , 51 ]. The simplified process was highly acceptable to individuals [ 25 , 48 ], but testing accuracy is a challenge to overcome [ 48 ], and it may additionally require trained technicians or lab-based enzyme immunoassays or equipment for sample preparation such as requiring a centrifuge for target analyte separation [ 51 ]. Future development needs to consider combining sample preparation steps together with detection and readout into one single device, without sacrificing testing accuracy.…”

Point-of-Care Testing for Hepatitis Viruses: A Growing Need

“…Indeed, a metaanalysis that included 30 studies evaluating the performance of 33 different HBsAg LFTs found an overall sensitivity of 90.0% (95% CI, 89.1-90.8%) and specificity of 99.5% (95% CI, 99.4-99.5%) [88]. More recent evaluations of commercial HBsAg LFTs have shown sensitivities above 91% and specificities above 94% [89][90][91]. Mutations within the antigenic determinants of HBsAg appear to have little impact on the performance of certain HBsAg LFTs, although this may depend on the specific antigen epitopes that are recognized by the antibodies used in the test [92].…”

Hepatocellular carcinoma in Indigenous Australians: a call to action

“…Where this is not feasible, evidence‐based models of outreach specialist care should be implemented in collaboration with Indigenous communities. Indigenous nurse practitioners embedded within multidisciplinary liver disease teams, integration of hospital and remote health services through telehealth initiatives (eg, the Project ECHO model of care [https://hsc.unm.edu/echo/], where primary care workers can discuss cases with specialists via virtual case conferences in regional and remote areas), and Indigenous peer‐led navigation of health service programs have successfully improved liver disease screening, management and cancer surveillance uptake here and overseas 18‐23 …”

“…Medicare rebate reforms to sustain telehealth initiatives developed during the coronavirus disease 2019 pandemic would be beneficial. Incorporating viral hepatitis diagnostic point‐of‐care tests into nurse‐led models of care could overcome barriers to diagnostics access in remote communities 18 . Public–private initiatives to financially support Indigenous health worker training are imperative to increase and retain the Indigenous health workforce.…”