To the best of our knowledge, this is the first study globally to report on the usability and acceptability of an oral fluid-based HCV antibody self-test among the general population in an LMIC setting. The 116 study participants were enrolled from attendees at two outpatient clinics in the Nile Delta region of Egypt, a region with a high HCV prevalence but also a high level of awareness of HCV infection. Overall, our study showed high usability and acceptability of HCVST. The majority of participants were able to correctly perform HCVST, following a short one-to-one demonstration on how to use the test. Although most participants (88%) conducted the HCVST process without any mistakes and interpreted the results correctly, more than half (53.4%) were observed to have difficulties with at least one step, and 14 participants (12%) requested assistance (four required assistance with more than one step in the testing process). The most common errors were incorrect handling of the test device (i.e., a participant touched the flat pad), incorrect timekeeping, and misinterpretation of test results. The most frequently observed difficulties related to removing the cap from the test tube (41.4%) and sliding the tube into the stand (18.1%).
Our findings are broadly consistent with those from earlier, comparable studies of HIVST [28, 29]. In a 2014 study of the usability of five different HIV self-test devices in unsupervised settings in Kenya, Malawi, and South Africa, 15% of participants made more than one error with an oral fluid self-test . Similar user errors and difficulties have been reported in other HIVST studies [12, 13, 24], especially with early prototype test kits and instructions for use that were not yet optimized for self-testing . The most common errors with oral fluid HIVST kits were incorrect swabbing of the gums and misinterpretation of the results, particularly those with faint positive lines. With blood-based HIVST kits, difficulties in sample collection were documented in 5–31% of participants, especially among those from high-risk populations [12, 27]. Generally, fewer user errors were reported when there was in-person observation, video recording of participants, provision of additional training, or direct supervision .
In the present study, overall inter-reader agreement was 86%, with a Cohen’s kappa value of 0.6. Three participants yielded invalid self-test results, although they had all collected their sample correctly and read the results after waiting for the appropriate length of time (Additional File 2). Five participants reported positive test results as negative and four reported negative results as positive. More than half of these misinterpretations (5 out of 9) were among participants with low levels of education or literacy (Additional File 2). The two participants who were unable to interpret their test results were both aged more than 60 years and had only received primary school education. The inter-operator concordance (i.e., comparing self-test results with the results of a rapid test performed by a provider) was 92.7%, with a Cohen’s kappa value of 0.75. These values fall within the range of 85.4–100% and 0.28 to 0.99, respectively, reported in a previous systematic review of HIVST studies . The pooled kappa value in this systematic review also showed comparable results for directly assisted (0.98, 95% CI 0.96–0.99) and unassisted HIVST (0.97, 0.96–0.98), suggesting that self-testers can perform HIVST as well as trained providers. In an HIVST study with relatively low levels of agreement (kappa value 0.47, − 0.04 to 0.97), conducted in rural Zimbabwe, the study investigators attributed the poor performance to both low levels of literacy in the population tested and suboptimal instructions for use . While in our study the overall concordance rate was high, we found three false-negative and three false-positive results, indicating that additional support for self-testers may be needed in the initial phases of implementation.
There was a high level of pre- and post-test acceptability of HCVST in our study, consistent with reports for HIVST [10, 12]. The majority of study participants rated the HCVST procedure as easy or very easy and stated that they would be willing to use a self-test again and recommend it to their friends and family. The most common reasons expressed for preferring to use a self-test were greater privacy and the possibility to perform a self-test at any time. The majority of participants were also aware of the need to contact health services for confirmatory viral load testing and to determine their eligibility for treatment. Although we used an oral fluid-based test, 24% of participants expressed a preference for blood-based assays. While the reasons for this preference were not sought in our study, extensive research into HIVST has shown that people express no clear preference for blood versus oral fluid HIVST kits. Some people express a preference for oral fluid tests because they are pain-free and easy to perform, while others prefer blood-based tests because of their perceived greater accuracy [12, 32–34]. Recent WHO guidance on HIVST encourages country programs to offer a choice in the type of self-test kits offered and sample types collected, promote supplier diversity, and address the preferences of different population groups . Further work is ongoing to assess the usability of blood-based self-tests for HCV.
This study has several limitations that must be considered when interpreting the findings. The sample size of 116 participants was small, and the study was based on the use of an oral fluid test only. The findings may therefore not be generalizable to the larger HCV-infected population in the community in Egypt, or to other sample types. The provision of an initial in-person demonstration for all participants in this study, combined with the observation of participants during the HCVST process and availability of assistance, may also have influenced how the HCVST procedure was conducted, resulting in fewer errors and difficulties. Egypt has a well-established, effective, and free national HCV testing, care, and treatment program . High levels of awareness about this disease and ready access to confirmatory testing and treatment in Egypt is likely to have contributed to higher levels of acceptability than in settings and populations without such a program. For example, a recent study among PWID in the UK found a lower acceptability of HCVST; perceived barriers in access to confirmatory testing and treatment, as well as a lack of post-testing counselling and the need to cope with test results in isolation, were among the key concerns expressed .
What are the implications of our findings for future HCVST implementation projects? First, there is a need to minimize errors and difficulties related to self-testing, by simplifying test procedures, improving test devices, optimizing instructions for use, and providing support tools. This may include the use of instructional videos as well as virtual and even in-person assistance for some individuals or populations, for example those with low literacy levels. Additional support tools to accompany further roll-out of HCVST and linkage to care may include telephone hotlines, interactive resources in social media, and mobile apps. Such tools have been developed and successfully implemented during the roll-out of HIVST [8, 11].
In addition to the four other recently completed HCVST studies that used the same protocol as this study, in high-risk populations in Vietnam, China, Georgia, and Kenya, there is a need to evaluate a range of oral fluid- and blood-based HCVST assays in different populations and settings. Additional studies are needed to compare the HCVST approach with other community- and facility-based HCV testing to identify the optimal positioning of self-testing for promoting access to testing and treatment. This includes impact on linkage to care. Although randomized clinical trials have shown that HIVST can achieve linkage rates comparable with standard testing following a reactive result , HCV diagnosis requires a two-step process, with viral load confirmation following positive serology test result, and HCVST will require specific strategies and messaging to promote linkage to care.
Overall, our study demonstrated the feasibility of assisted self-testing for HCV in a general population sample from a semi-rural setting in the high HCV prevalence Nile Delta region. Although there has already been a substantial investment in HCV case-finding, with more than 60 million people tested through the recent national campaign in Egypt, HCVST may still have a role to play in promoting access to testing among those not yet reached. This could include young people, college students, migrant workers, and certain marginalized populations, such as MSM and PWID, or those with limited access to healthcare facilities.