February 21, 2019
2 min read

Higher limit of detection identifies 97% of HCV viremic infections

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Researchers determined a target limit of detection for hepatitis C point-of-care tests that would identify 97% of viremic infections among all populations including low- and middle-income countries, according to a recently published study.

“Available tests for viremia are expensive, and require advanced laboratory facilities, electricity, water, and refrigerated reagents,” J. Morgan Freiman, MD, from the Boston Medical Center in Massachusetts, and colleagues wrote. “A rapid, affordable, easy-to-use test for confirmation of HCV viremia at the point-of-care (POC) that can be deployed on a large scale has the potential to improve outcomes across the diagnosis and care continuum, particularly in high HCV prevalence settings.”

To determine the target limit of detection (LOD) necessary to diagnose the highest percentage of patients with HCV eligible for treatment and identify characteristics associated with low-level viremia, the researchers evaluated 66,640 patients with viremic HCV who were not on treatment.

The dataset included patients from Georgia (44.4%), Canada (40.9%), India (8.1%), Cambodia (2.6%), Egypt (1.6%), Pakistan (1.3%), Cameroon (0.4%), Indonesia (0.2%), Thailand (0.2%), Vietnam (0.1%), Malaysia (0.05%), and Mozambique (0.02%).

The LOD was 3,311 IU/mL (95% CI, 3,256.3-2,268) for the 95% percentile, 1,318 IU/mL (95% CI, 1,298.4-1,322.3) for the 97% percentile, and 214 IU/mL (95% CI, 207.1-218.6) for the 99% percentile.

Factors associated with higher odds for low-level viremia included age 18 years to 30 years vs. age 51 years to 64 years (OR = 2.56; 95% CI, 2.19-2.99), female vs. male sex (OR = 1.32; 95% CI, 1.18-1.49), genotype 2 (OR = 1.24; 95% CI, 1.07-1.43) and genotype 3 (OR = 1.17; 95% CI, 1.03-1.33) vs. genotype 1, and fibrosis stage 4 vs. stages 0 to 1 (OR = 1.44; 95% CI ,1.21-1.69.

Freiman and colleagues noted that a test with a 1,318 IU/mL LOD would be approximately 100 times higher (or less sensitive) than the current “gold-standard” nucleic acid tests with a 97% detection rate for HCV viremia.

“While an increase in LOD may not impact cost and development of near patient molecular technologies, it sets an achievable LOD for immunoassays such as those that involve HCV core antigen detection,” the researchers wrote. “Comparative and cost-effectiveness analyses will be needed to investigate settings that may benefit the most, and to quantify how a less sensitive test might impact the diagnosis, treatment and cure cascade in [low- and middle-income countries].” – by Talitha Bennett

Disclosure: The authors report no relevant financial disclosures.