Diagnostic strategies to enhance testing for hepatitis C virus infection

Background: Simplified and affordable HCV diagnostic pathways that incorporate innovative collection and testing methods are required to globally scale up HCV elimination efforts. This is especially applicable among highly marginalised populations. Aims: The aim of this research was to evaluate the performance of emerging diagnostic technologies with novel sample types such as dried blood spots (DBS) and finger-stick samples in clinical and decentralised settings. The specific aims include 1) Assessing performance of the Aptima HCV Quant Dx real-time assay for HCV RNA detection using DBS (from a laboratory and cohort collected population), 2) Evaluating performance of HCV core antigen (HCVcAg) detection in plasma and DBS, and 3) Performing a systematic review of point-of-care and DBS HCV RNA testing. Methods: In Chapter Two, HCV RNA detection from retrospective paired plasma and laboratory spotted DBS was compared on the Aptima assay. The same evaluation was performed in Chapter Three, however paired finger-stick capillary DBS and venepuncture collected samples obtained through the LiveRlife study (observational cohort study) were tested. In Chapter Four, detection of HCVcAg from plasma and DBS samples (LiveRlife study) was evaluated on the ARCHITECT-i2000R analyser. For Chapters Two, Three and Four data were analysed for assay sensitivity, specificity, bias and agreement and participant characteristics (Chapters Three and Four only) using statistical methods including paired T-test, Deming correlation, Bland-Altman, data distribution and summary statistics. In Chapter Five, bibliographic databases and conference presentations were searched for eligible studies. Meta-analysis was used to pool estimates. Key Findings: Laboratory spotted and clinically collected DBS samples tested on the Aptima assay displayed good sensitivity, specificity, and correlation to plasma for the detection of HCV RNA. HCVcAg testing in plasma may be an affordable tool for determining active HCV infection with the potential to reflex test from a positive anti-HCV antibody result. HCVcAg DBS testing showed lower sensitivity but may be suitable for screening high-risk populations in countries with medium to high (1.5-3.5% and >3.5%) HCV prevalence. Results from our systematic review showed excellent diagnostic performance among assays that detect HCV RNA from finger-stick whole blood and DBS samples. However, the proportion of invalid results following Xpert HCV Viral Load Finger-stick testing highlights the importance of operator training and quality assurance programs. Conclusion: Novel collection and testing methods, including DBS and finger-stick point-of-care are suitable diagnostic alternatives to standard pathology testing. A targeted testing approach that considers the setting and population could facilitate enhanced HCV testing, linkage to care and treatment