One-Step HCV RNA Tests Help Encourage Hepatitis C Screening
Viral hepatitis is responsible for 1.34 million worldwide deaths each year, as many as HIV/AIDS, tuberculosis, or malaria. The World Health Organization (WHO) has recognized the critical role played by laboratory diagnostics in eliminating the hepatitis C virus (HCV) by 2030. Onsite HCV screening using fingerstick technology offers the promise of rapid, cost-effective, and accurate […]
The Diagnostic ChallengeConventional HCV testing requires patients to make multiple clinical visits. During the first visit, clinicians perform a test for HCV antibodies. A positive test result means only that the patient has been exposed to the virus. The patient must then schedule another visit to be tested for HCV RNA to determine the presence of active infection. Sometimes subsequent visits are necessary. All of this requires laboratory analysis, trained phlebotomists, sample preparation, and other test resources. And in many cases, patients who test positive in visit one do not follow up with a second visit. New products from companies like Cepheid, OraSure, and Abbott Laboratories enabling detection of active HCV infection in a single step may be much more effective in engaging patients and convincing them to get screened. There are two basic kinds of HCV tests: 1) HCV RNA tests that can be done at the point of care (POC) on a drop of blood that is self-collected via fingerstick; and 2) tests that detect HCV RNA from a laboratory using dried blood spots collected at the site of care.
Use of POC HCV Screening Tests on Injection Drug UsersOne of the biggest advantages of POC HCV tests and dried blood spot sampling (DBS) is enabling testing of people in different nonclinical settings such as drug treatment centers. This is highly significant because people who inject drugs (PWID) are at particularly high risk of contracting HCV infection. Studies have demonstrated the effectiveness of POC and DBS testing of PWID in these settings.
The Paris StudyA study from the US National Library of Medicine and National Institutes of Health published in the journal Open Forum Infectious Diseases in June 2020 evaluated whole blood POC HCV RNA testing and fingerstick DBS sampling on HCV-seropositive PWID attending two drug treatment services and one supervised consumption room in Paris. Of the 89 participants enrolled, HCV RNA was detected in 34 (38.6 percent). Fingerstick whole blood POC RNA testing and HCV RNA detection from DBS samples were found to be feasible and acceptable among PWID with no major difference in terms of HCV RNA detection rate. Overall, 16 participants received pan-genotypic antiviral treatment. The proportion of PWID with sustained virologic response at 12 weeks was 81.2 percent. A one-step screening strategy based on the detection of HCV RNA would engage people in care for treatment scale-up and HCV elimination, the researchers concluded.
The Barcelona StudyAnother study published in June 2020 in the International Journal of Drug Policy compared the effectiveness of the different single-step HCV screening methods on PWID attending a drug consumption room (DCR) in Barcelona, Spain. Performance of each test strategy was based on comparison with the reference method. The researchers determined HCV genotypes/subtypes and HIV status by sequencing and serology, respectively, and administered a questionnaire on preferences regarding delivery of test results. Prevalence of HCV RNA was 63.0 percent (of which 25.8 percent were co-infected with HIV. The RNA POC tests showed a sensitivity of 98.4 percent for detectable viral loads and 100 percent for quantifiable viral loads. The DBS-based assay had a sensitivity of 93.7 percent for detectable viral loads and 96.7 percent for quantifiable viral loads. There were no significant differences between the sensitivity values of these two strategies, and the specificity was 100 percent in both cases, the researchers found. Half of the participants preferred to receive the HCV RNA result on the same day, and 80 percent received their RNA POC test results on the same day. Both the HCV RNA POC test and DBS-based assay are highly reliable tools for the simplified diagnosis of HCV among current PWID, the researchers concluded.
The Italian StudyA study presented during the Liver Meeting Digital Experience in Nov. 2021 found that onsite screening with a fingerstick assay at addiction treatment centers in Italy increased diagnosis and treatment of HCV among PWID. The researchers invited 909 PWID from five different addiction treatment centers to participate in HCV screening using a fingerstick capillary whole-blood RNA test. The results were delivered directly to the patient after 60 minutes. Among the 872 (96 percent) who opted to participate, the mean age was 42.6 years, 78 percent were male and the mean duration of opioid agonist therapy was 10.3 years. Additionally, 64 percent had a history of injection drug use and 69 percent had a history of tattooing. Nearly 40 percent of the participants had never been screened for HCV before. Twenty percent of the patients were HCV RNA-positive, with genotypes 1 and 3 being the most common. Among the HCV RNA-positive, 88 percent were linked to care. Sixty percent of those patients subsequently completed treatment, all of whom achieved sustained virologic response. “This is one of the largest HCV RNA screening and linkage to care projects performed in people who use drugs attending our treatment centers,” according to lead researcher Roberto Somaini, PhD. “This project evidenced the feasibility and acceptability of onsite testing using HCV RNA viral load fingerstick assays, with 96 percent of the people accepting to undergo this type of screening.”
TakeawayEvidence of the effectiveness of one-step HCV screening methods on PWID continues to mount. This bodes well for future treatment of not just vulnerable people but the general population.
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