Screening Technologies and Development of Non-invasive Techniques
Recent technological advances in diagnostic testing and the use of less-invasive techniques are being increasingly used to overcome barriers to testing.
Most Routinely Performed Invasive Technology
- Venapuncture or venipuncture is the process of obtaining intravenous access – through a vein – for the purpose for blood sampling. This procedure is usually performed by medical practitioners, phlebotomists or nursing staff.
- Venapuncture is one of the most routinely performed invasive procedures and is routinely carried out in clinical settings to obtain blood for diagnostic purposes.
- Although other veins can and are often used, blood is most commonly obtained from the median cubital vein. This vein lies close to the surface of the skin on the inside of the elbow and in most people, can be readily accessed.
However venous access for people with a history of injecting may be compromised making venipuncture unsuitable and a barrier to testing.
Recent technological advances in diagnostic testing and the use of less-invasive techniques including dried blood spot testing (DBST) and other rapid diagnostic tests (RDTs) is becoming more established. These newer technologies are being increasingly used to overcome barriers to testing, improving access to affected communities through both healthcare and community outreach settings and potentially, through peer delivered interventions.
+Dried blood spot testing:
Dried blood spot testing (DBS), which requires a much smaller sample of capillary blood to be taken using a finger prick to filter paper, can improve testing uptake, particularly among hard-to-reach (e.g. PWID) populations.
Simpler and painless
Collection of blood spots is a relatively simple and nearly painless procedure and can be performed by trained, supervised non-clinical personnel making testing easier in non- clinical (e.g. drug treatment/harm reduction/ pharmacy) settings.
DBS, as well as being used to collect whole blood specimens in order to perform EIA detection of antibodies to hepatitis B and C in a central laboratory, is now increasingly being used as a reliable alternative to venepuncture sampling for point of care screening and confirmation of current hepatitis B and C infection.
+Rapid diagnostic tests (RDTs)
Time and cost effective
Innovations in viral hepatitis testing and RDTs now include point-of-care assays for nucleic acid testing (NAT) and core antigen, which avoid the need for expensive laboratory processing. These newer testing technologies don’t require extensive training to deliver and are now sufficiently sensitive, specific and convenient to offer a time and cost-saving alternative to conventional tests.
RDTs which provide same-day point of care results are recommended for use by EASL in settings with limited access to laboratory services, and in particular to improve access in hard-to-reach and rural populations.
The sensitivity and specificity of some of the latest generation of RDTs can be comparable to those of EIAs. However, the quality of assays is variable. A variety of RDTs are under evaluation and/or are currently in use in low- and middle- income countries for screening, diagnostic and surveillance purposes.
Benefits of RDTs
- The simplicity, relatively low cost and rapid turnaround time of RDTs, can substantially improve access to HCV testing, enhance linkage to care and reduce loss to follow-up.
- RDTs provide same-day results and do not require complex equipment or advanced training. They can be performed outside of a traditional laboratory setting by persons without a laboratory background who have been trained to conduct the testing process using an RDT.
- Affected populations and health workers show strong support for the use of RDTs delivered at the point-of-care to overcome barriers associated with conventional testing methods and promote access to care.
- RDTs can be performed by readily trained non-medical practitioners and can be used in outreach programmes (e.g., prison services, substance use/treatment services) to increase the uptake of hepatitis screening.
- RDTs are likely to be cost-effective and may mitigate the difficulties of inefficient specimen collection, processing and transportation to laboratory services, and allow for the simplification and decentralisation of testing.
- Systematic reviews of RDTs have shown high sensitivity and specificity across a wide range of settings and different populations which compare highly with laboratory-based reference EIAs.
- RDTs that used oral fluid (of particular value where collection of venous or capillary whole blood is challenging) also had adequate sensitivity and specificity.
+ Self testing
Testing at home
New assays have been developed that in the future will also give the potential for home or self-testing of blood-borne viruses. Self-testing is a process in which a person who wants to know their status collects a specimen, performs a test and interprets the result themselves, discreetly and conveniently.
The experience with hepatitis self-testing is currently very limited, but, based on experiences with HIV self-testing, represents a potentially important approach to optimise viral hepatitis testing in the future and to facilitate increased access to comprehensive viral hepatitis testing, treatment and care for hard to reach populations.
“Simple technologies are required to ensure that testing services can reach remote areas and hard-to-reach populations.
Priority should be given to the development of rapid diagnostic tests for diagnosing viral hepatitis B and C infection, point-of-care tests for monitoring hepatitis B and hepatitis C viral load (and hepatitis C virus antigen) to guide treatment decisions.”
Global Health Sector Strategy on Viral Hepatitis 2016 -2021. WHO (2016)