This study demonstrates that the OraQuick® anti-HCV rapid test by finger-prick is widely accepted and preferred in this sample of young adult PWID in San Francisco. This preference was not associated with sociodemographic characteristics, including age, gender, race/ethnicity, HCV and HIV testing history, or reported injection risk exposures. The principal reason participants indicated for preferring the rapid test was wanting fast results regarding anti-HCV status and with potentially less pain than with testing using a blood draw. An important indication that the test was acceptable was the widespread endorsement that they would recommend it to a friend. As hoped, these results suggest that rapid HCV testing has potential to increase HCV testing and knowledge of exposure to HCV infection. We also found that test preference did not differ by anti-HCV results; those testing positive were equally likely to favor the rapid test as those testing negative. This is important since follow-up testing for those testing anti-HCV positive will require a blood draw for HCV RNA testing. These results suggest that those at highest risk are not deterred from anti-HCV testing, or the potential for additional testing that may follow positive results.
In the U.S., there is growing concern about an emergent HCV epidemic in young adult PWID, not only in urban, but suburban and rural areas
, and reflected by disproportionate increases in the number of acute HCV cases identified among young PWID and reported to the CDC in the past five years
. Our population is comparable to other studies of young adult PWID sampled in urban areas and in national surveys
[17, 25, 53–56]. The large number of participants who were unstably housed or homeless presents another significant concern and potential opportunity for the implementation of this test. Evidence shows worrying rates of injection drug use among homeless youth
. These factors, and others, including mobility
, coupled with barriers to phlebotomy-based testing faced by homeless youth
[21, 32, 33], increase the imperative for more accessible options for HCV testing, prevention and linkages to care, and reinforce our focus on this population.
This test offers a critical opportunity to increase HCV testing among high risk young adult PWID, as well as access to other health services, including counseling to reduce risk behaviors and linkage to care. As evidenced by the introduction of rapid HIV testing, being able to offer rapid testing and immediate results may be the determining factor in increasing testing numbers, results disclosures and appropriate counseling services
[43, 45, 59]. Comprehensive prevention programs that provide testing options, along with clean injection equipment, substance use treatment options, health education, and opportunities to access treatment and care, could potentially stem infection rates among young PWID
[60, 61]. Rapid HCV testing could be an essential component of such an inclusive approach. A majority (over 80%) of participants in this study report using needle exchange services. Implementation of rapid testing at such programs has potential to reach a large number of PWID. Knowing one’s HCV status is also critical to seeking and getting access to the appropriate care. Improved treatment options that are more tolerable and effective are likely to increase the demand for faster, more accessible testing options, together hopefully increasing access to care and treatment.
The rapid anti-HCV test remains limited by the need for nuanced counseling messages associated with anti-HCV testing, and by the need to confirm positive results. A single rapid test does not distinguish between those individuals with current HCV infection and those with past infection who have cleared the virus, nor will it give a clear picture of acute versus chronic infection. For this reason, viral RNA testing remains necessary for accurate knowledge of HCV infection status
. The HCV RNA test is associated with phlebotomy and lab work and participants must return for results, although use of dried-blood spots for HCV RNA testing is feasible and accurate
[62, 63] and testers might circumvent phlebotomy in some cases. In addition, testing sites without trained phlebotomists or the resources to offer RNA testing will have to provide referrals to clinical sites for people with positive HCV antibody. Many of the aforementioned barriers associated with testing that young PWID face, such as venipuncture and returning for results, thus remain a potential problem if someone tests anti-HCV positive.
Although the antibody testing does not give a clear picture of infection status or timeline, the rapid test may be more accessible and cheaper, facilitating serial testing among those who are negative and at high risk. Rapid testing could, then, help providers estimate a window of when someone newly acquires HCV, offering an important opportunity for prevention messages and referral to confirmatory testing and care, as new infections are marked by high viremia and these individuals are potentially at high risk of HCV transmission
This study is limited by the fact that participants were already engaged in a study of HCV transmission and risk, had previously agreed to regular HCV testing, and may have received a HCV test prior to the baseline visit. Participants also understood that they would receive a phlebotomy blood draw as part of that study, regardless of whether they chose the rapid test or not. This study, therefore, does not necessarily represent individuals who are not already seeking and engaged in testing. Nevertheless, our population is highly reflective of the population at high risk of HCV, especially those in urban areas
[13, 16, 57]. Generalizability of the favorable preference profile for the rapid test is also limited by the fact that all participants underwent phlebotomy-based testing for HCV RNA testing. Current HCV screening algorithms recommend reflexive testing for HCV viremia only among those testing anti-HCV positive
. Furthermore, as the rapid test may be implemented in settings where there are limited clinical staff, options for HCV RNA testing may be more limited. However, given the high rate of infection and the long seronegative viremic window observed in acute and early HCV infection, there is a need to find other methods to detect viremia in PWID in order to reduce the risk of HCV transmission during the seronegative window
. It is possible that our sample also had familiarity with rapid HIV testing, which could result in overestimates of the acceptability of HCV testing. We note, however, that HIV testing in the UFO Study is voluntary and not part of routine research testing. Since we have not measured the types of HIV testing that participants have had we cannot assess the effect of this potential exposure.
Through its accessibility in non-medical settings by lay-workers, by not initially requiring phlebotomy or accessible veins, and by providing immediate results, rapid testing offers an important opportunity to enhance prevention programs, and streamline access to care and treatment, adding a critical new dimension to preventing and treating HCV among vulnerable populations. Preference and acceptability should be assessed among those not already being tested, in real-world settings and at other community settings, such as substance abuse treatment centers, drop-in services, and needle exchange programs.