Dried blood spots perform well to identify patients with active HCV infection in Vietnam

Abstract

Recently, treatment advances in direct‐acting antivirals have radically changed the management of HCV patients. However, in resource‐limited countries, identification of patients with active HCV infection is still challenging in remote settings due to the limited access to laboratories able to measure HCV viral load. This study evaluated whether dried blood spots (DBS) transferred to a central laboratory could overcome this challenge. A total of 315 HCV‐infected patients, naïve to anti‐HCV treatment, provided each three type of samples: plasma, DBS with calibrated quantities of venous blood and DBS with uncalibrated quantities of capillary blood. Qualitative comparison was conducted in terms of detection of HCV viral load on DBS as opposed to plasma to estimate sensitivity and specificity. Quantitative comparisons were conducted by means of correlation estimation. Of the 250 patients with detected plasma HCV viral load, 245 also had detectable DBS HCV viral load (capillary or venous) leading to a sensitivity of 98.0% (95% confidence interval (CI): 95.4%‐99.3%); importantly, all measurements with a plasma HCV viral load >118 IU/mL were also detected in DBS. When HCV was not detected in plasma, it was also not detected in DBS resulting in 100% specificity (95% CI: 94.5%‐100%). Quantitative HCV viral load results were very similar when utilizing plasma or DBS sample types as illustrated by correlations >0.99. In conclusion, DBS sample types, with either uncalibrated capillary blood or calibrated venous blood, performed well to distinguish patients with active HCV infection, and who therefore need treatment, from other patients.

Laboratory‐based testing for hepatitis C infection using dried blood spot samples: A systematic review and meta‐analysis of diagnostic accuracy

“…The 20 studies investigating the diagnostic accuracy of HCV‐RNA tests in DBS were published between 2002 and 2020 63,67,78,81,82,85,88–101 . Of these, 9 were cross‐sectional, 81,89,90,93–97,100 and 11 were case–control 63,67,78,82,85,88,91,92,98,99,101 .…”

“…Of these, 9 were cross‐sectional, 81,89,90,93–97,100 and 11 were case–control 63,67,78,82,85,88,91,92,98,99,101 . Sixteen studies were from high‐income countries, 67,78,81,82,85,88–93,96–99,101 and 4 were from lower–middle‐income countries 63,94,95,100 . Overall, samples from 2940 participants (study sample size range: 25–511) were compared.…”

“…25,[111][112][113] Our systematic review and meta-analysis of DBS samples included evidence from eight additional studies on anti-HCV, 63,66,69,71,73,74,86,87 and 11 additional studies on HCV-RNA. 63,89,90,[92][93][94][95]97,98,100,101 Accordingly, the international literature indicates that DBS samples can be used to provide an accurate diagnosis of prior exposure to HCV and/or current infection. Given these findings, DBS could be used in low-resource settings and settings where the collection of a blood sample by venepuncture is challenging (e.g., drug service centres), but importantly also in settings where reflex testing is not feasible due to the logistical challenges associated with its use (e.g.,…”

“…63,67,78,82,85,88,91,92,98,99,101 Sixteen studies were from high-income countries, 67,78,81,82,85,[88][89][90][91][92][93][96][97][98][99]101 and 4 were from lower-middle-income countries. 63,94,95,100 Overall, samples from 2940 participants (study sample size range: 25-511) were compared. The prevalence of HCV-RNA was 62% (range: 27%-85%).…”

“…Overall, 6 of the studies were rated as at low risk of bias, 89,90,94,96,97,100 10 were at moderate risk of bias 63,67,81,82,88,[91][92][93]95,98 and 4 were at high risk of bias. 78,85,99,101 Common issues were identified in relation to patient selection, 63,67,78,82,85,88,89,[91][92][93]95,[97][98][99]101 interpretation of index test results, 63,67,78,81,82,85,88,[90][91][92][93][94][95][98][99][100]…”