Prevention in Focus

Spring 2021 

Dried blood spot collection for hepatitis C and HIV testing in Canada

By Mallory Harrigan

Dried blood spot (DBS) collection is a promising approach to hepatitis C and HIV testing that can reach people who might not access traditional health services. Using this method, a sample of blood droplets is collected on a filter paper and then dried for transportation to a laboratory where standard hepatitis C and/or HIV testing is performed. The ease of sample collection and the stability of the collected sample make DBS collection a useful tool. This approach is not yet widely used in Canada for hepatitis C and HIV testing, but it may become more widely available in the coming years as it has the potential to complement existing testing options. This article will explore what DBS testing is, the advantages of DBS testing and its use in Canada.

What is dried blood spot testing?

DBS testing is a method of blood collection that can be used for diagnostic hepatitis C and HIV testing. It was originally developed as a method to collect blood to test for metabolic disorders in newborns. Through this method, samples of blood are collected from a finger prick (or heel prick in infants), dropped onto a filter paper and then dried for transportation to a laboratory.1 DBS samples do not require special storage. At the laboratory, the dried blood spots are rehydrated and then the laboratory can conduct the same tests that would be used on a venous blood sample.2 The reliability and accuracy of DBS testing for hepatitis C and HIV approaches that of standard blood-based testing methods.3–6 However, it should be noted that with hepatitis C testing, DBS samples sometimes do not provide a large enough sample for hepatitis C genotyping and viral load testing.7

What are the advantages of DBS testing compared with other testing methods?

Barriers to hepatitis C and HIV testing exist in Canada, and as a result an estimated 44% of people with a chronic hepatitis C infection are undiagnosed8 and 13% of people with HIV are undiagnosed.9 Testing is an important step to linking clients to prevention, care and treatment services for both HIV and hepatitis C.

Compared with other types of testing, DBS testing has advantages that could reduce some barriers to hepatitis C and/or HIV testing. If DBS testing becomes more widely used, this additional option could help to reach more people who are undiagnosed.

The sample can be collected by lay providers or self-collected

DBS sample collection can be performed by trained lay providers because the samples are easy to collect and do not require a blood draw. The flexibility of allowing people with a connection to a community (for example a peer) to be trained to collect the sample may increase trust and result in higher rates of testing.10 It is also possible for people to collect the blood sample themselves (called self-collection), which can be a convenient option.

It is an alternative for people who are unable to provide a venous sample

DBS collection can be used to collect blood when a person cannot provide a venous blood sample. For example, it is a good option for people who have damaged veins because of drug use.7

The sample is easier to store and ship

DBS test samples are very easy to store (e.g., they do not require refrigeration) and ship. Once the blood has dried on the filter paper, the sample is stable. As a result, DBS test samples can be sent to a laboratory without the need for the specialized transportation and packaging that is required for the tubes of blood used in regular testing. This is especially beneficial in communities that do not have the ability to store and ship standard venous blood samples at the necessary temperatures.1 This is more convenient and less expensive than the process for transporting standard blood samples from remote areas to a testing laboratory.

Testing can be performed in a variety of locations

Given the ease of collection and storage, DBS testing can be offered in a variety of locations outside of medical offices or facilities, expanding access to testing services.1,11 This could lead to higher rates of testing among people living in remote communities where testing options are limited.

DBS can be used to diagnose multiple infections

DBS can be used to test for multiple infections on the same card (e.g., HIV, hepatitis C and syphilis).12 Because HIV, hepatitis C and other sexually transmitted infections share common transmission routes and risk factors and affect similar priority populations, the integration of testing for multiple infections can ensure that infections do not go undiagnosed.  

DBS can reduce loss to follow-up for confirmatory testing

With DBS testing, the collected sample can be used for both screening and confirmatory testing. If the screening test is reactive, a confirmatory test can be run on the same sample. This gives DBS tests an advantage over some other screening tests, which may require the person to get their blood drawn for confirmatory testing at a later date. Sometimes it can be a challenge to reach people for confirmatory testing, and if people do not undergo confirmatory testing they will not receive treatment and care.1

Results are not given in the same visit as sample collection

With DBS tests, the results are not given in the same visit as when the sample is collected, unlike point-of-care testing. Anecdotal evidence from communities in Canada where DBS testing has been rolled out suggests that there are benefits to the results not being given in the same visit.13 Some people prefer to have time between the sample collection and receipt of their results, to prepare psychologically for their result.14 Also, if the provider collecting the sample is known to the person being tested, it can be an advantage that the person collecting the sample will not know the test result.

How widely is DBS testing for hepatitis C and HIV being used in Canada?

The use of DBS testing for diagnosing hepatitis C and HIV is very limited in Canada at present, with few public health laboratories currently processing DBS samples. Most of the DBS testing in Canada is being done in remote Indigenous communities where accessing traditional testing can be a challenge.14–16

There are a few reasons why DBS tests are not being used more widely in Canada to diagnose HIV and hepatitis C. First, it is labour intensive and costly for laboratories to prepare the sample for testing.15 In addition, each public health laboratory is required to independently validate the test before being able to offer it. Lastly, DBS testing is only preferred or necessary in certain situations, such as when traditional testing is a challenge (e.g., when it is difficult to transport samples over long distances or to access a client’s vein).

There is hope that the use of DBS testing may be expanded in the coming years. In 2018 the federal government allocated funds for the development of innovative testing approaches, including DBS testing, to reach more people who are undiagnosed, especially in rural and remote communities.17 In addition, there are studies being planned that will use DBS collection to test for COVID-19 antibodies,15 which may help to increase Canada’s capacity to process DBS samples. This will potentially improve the ability of public health laboratories to process DBS cards for diagnostic hepatitis C and HIV testing.

Although the use of DBS testing to diagnose hepatitis C and HIV is limited, this sampling method has long been used in Canada for epidemiological studies through the National HIV and Retrovirology Laboratory.13 These studies are intended to assess the prevalence of the hepatitis C and HIV viruses in a population rather than to provide individuals with a diagnosis. DBS testing has been used for studies among gay, bisexual and other men who have sex with men18,19 and people who inject drugs.20 These studies suggest that using DBS testing is feasible in the populations most affected by hepatitis C and HIV in Canada.

The potential to increase testing

Given the unique advantages that DBS testing offers, such as the fact that DBS samples can be transported over long distances and remain stable and the fact that samples can be collected for multiple tests simultaneously, it has the potential to increase testing in certain populations.

Because DBS testing is currently limited in Canada, there has been limited research to date examining the impact of its use in communities. One small pilot program in Alberta used DBS testing for hepatitis B and C, HIV and syphilis at two Métis community events21 and provided evidence that this testing method was able to reach people who had previously not tested. Among 26 participants, 50% reported this was their first time getting tested for HIV, and 46% reported it was their first time getting tested for hepatitis C.

International research has shown that DBS testing programs increase uptake of hepatitis C and HIV testing. A review article included six studies that evaluated whether hepatitis C testing increased when a DBS testing program was introduced.22 All the programs were in the United Kingdom among people in prison or people with a history of drug use. In five of the six studies, the DBS testing intervention increased the number of hepatitis C tests, the number of new diagnoses or both. In the study that did not find an increase, there were logistical challenges that prevented the program from being rolled out as planned. This review was focused on hepatitis C testing, but in two of the studies, participants were tested for HIV as well. In one of those studies, an increase in HIV testing was observed when the program was introduced.23

Implications for service providers

Testing for hepatitis C and HIV using DBS samples is highly accurate and could increase the uptake of testing. It is important for service providers to be aware of the potential advantages of DBS testing and to consider whether its use could be beneficial to the populations that they serve. DBS testing can be useful in remote communities, in situations where there may be delays in getting samples to a laboratory, for people who have veins that are difficult to access or in situations where it is only feasible to collect one blood sample for both screening and confirmatory testing. Service providers will also need to consider whether they have access to a public health laboratory that can process DBS testing, as this access will differ across Canada. Service providers should consult their provincial or territorial local public health laboratory for more information. Service providers can also consider whether advocating for access to DBS testing is important in their regions and could help to expand access to testing.

Related resources

HIV self-testing

Dried blood spot testing: Accurate for both hepatitis C screening and confirmatory tests

Reaching the Undiagnosed: HIV self-testing in Canada – what should we expect?

References

  1. Tuaillon E, Kania D, Pisoni A et al. Dried blood spot tests for the diagnosis and therapeutic monitoring of HIV and viral hepatitis B and C. Frontiers in Microbiology. 2020 Mar 9;11:373.
  2. Parker SP, Cubitt WD. The use of the dried blood spot sample in epidemiological studies. Journal of Clinical Pathology. 1999 Sep;52(9):633-39.
  3. Lange B, Cohn J, Roberts T et al. Diagnostic accuracy of serological diagnosis of hepatitis C and B using dried blood spot samples (DBS): two systematic reviews and meta-analyses. BMC Infectious Diseases. 2017;17(Suppl 1):700. Available from: https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-017-2777-y
  4. Lange B, Roberts T, Cohn J et al. Diagnostic accuracy of detection and quantification of HBV-DNA and HCV-RNA using dried blood spot (DBS) samples — a systematic review and meta-analysis. BMC Infectious Diseases. 2017;17(Suppl 1):693. Available from: https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-017-2776-z
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  10. World Health Organization. HIV testing: WHO recommends HIV testing by lay providers. Policy brief. Geneva: World Health Organization; 2015. Available from: https://www.who.int/hiv/pub/toolkits/policy-hiv-testing-by-lay-provider/en/
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  12. British Columbia Centre for Disease Control.  Summary report: provincial point of care program 2013/14 – 2018/19. Vancouver: British Columbia Centre for Disease Control; 2020.  Available from: http://www.bccdc.ca/resource-gallery/Documents/Statistics%20and%20Research/Statistics%20and%20Reports/STI/CPS_POC_Program_Summary_Report_20200116.pdf
  13. CATIE. Dr. John Kim: Dried blood spot testing for HIV diagnosis in Canada [video]. Toronto: CATIE; 2017. Available from: https://www.youtube.com/watch?v=-zX3jtCRfoI&ab_channel=CATIEinfo
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  15. Kim J. Personal communication about dried blood spot testing in Canada. 2020 Oct.
  16. Public Health Agency of Canada. Horizontal evaluation of the federal initiative to address HIV/AIDS in Canada 2013-14 to 2017-18. Ottawa: Public Health Agency of Canada; 2019. Available from: https://www.canada.ca/en/public-health/corporate/transparency/corporate-management-reporting/evaluation/report-horizontal-evaluation-federal-initiative-address-hiv-aids-2013-2014-2017-2018.html
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About the author(s)

Mallory Harrigan is CATIE's knowledge specialist, HIV testing. She has a Master’s degree in community psychology from Wilfrid Laurier University.