Evaluation of the Xpert HCV Viral Load Finger-Stick Point-of-Care Assay

Remote areas of many low and middle income (LMI) countries have poor access to HIV viral load (HIV VL) testing. The SAMBA-II (Simple Amplification-based Assay) Semi-Q Whole Blood Test (Diagnostics for the Real World (DRW), Cambridge, UK) is a point of care assay which uses leucodepletion technology to allow whole blood testing in remote settings. 1540 consecutive HIV-positive clinic patients in Cameroon (250), UK (633), Ukraine (412) and Zimbabwe (245) donated venous blood (all countries) and finger-prick blood (all except UK) for testing on SAMBA-II. SAMBA II results were compared with simultaneous plasma results on the Abbott RealTime HIV-1 (Abbott Molecular, Des Plaines, IL) viral load assay and interpreted as either <1000 RNA copies/ml or ≥1000 RNA copies/ml. For 1528 venous whole-blood samples tested on SAMBA II, overall percent agreement with the reference test at a cut-off of HIV VL ≥1000 cps/ml was 96.9% (1480/1528 95% CI 95.9-97.7), negative percent agreement 97.7% (1259/1289 95% CI 96.7-98.4), positive percent agreement 92.5% (221/239 95% CI 88.4-95.5). For 854 finger-prick samples there was 95.0% (811/854 95% CI 93.3-96.3) overall percent agreement; negative percent agreement 98.0% (625/638, 95% CI 96.5-98.9); positive percent agreement 86.1% (186/216 95% CI 80.8-90.4). These rose to 93.5% (82.1, 98.6), 97.6% (95.6, 98.8) and 95.6% (93.3, 97.3) after exclusion of aberrant results from the Ukraine centre. These results show a high level of agreement between SAMBA-II and a laboratory-based assay. SAMBA-II has a performance that is suitable to use as a VL point of care assay in remote settings

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Field evaluation of Xpert ® HCV Viral Load point-of-care test for detection of hepatitis C virus infection by venipuncture-collected and finger-stick capillary whole-blood samples

Journal of Hepatology ◽

10.1016/s0168-8278(17)31900-1 ◽

2017 ◽

Vol 66 (1) ◽

pp. S709

Author(s):

J. Grebely ◽

F. Lamoury ◽

B. Hajarizadeh ◽

Y. Mowat ◽

A. Marshall ◽

...

Keyword(s):

Hepatitis C Virus ◽

Viral Load ◽

Hepatitis C ◽

Point Of Care ◽

Field Evaluation ◽

Hepatitis C Virus Infection ◽

Blood Samples ◽

Point Of Care Test ◽

Whole Blood Samples ◽

Finger Stick

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The Practicability of the Xpert HCV Viral Load Fingerstick Point-of-Care Assay in Primary Care Settings

Viruses ◽

10.3390/v13112327 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2327

Author(s):

David Petroff ◽

Olaf Bätz ◽

Katrin Jedrysiak ◽

Jan Kramer ◽

Thomas Berg ◽

...

Keyword(s):

Primary Care ◽

Viral Load ◽

Primary Care Physicians ◽

Point Of Care ◽

Linkage To Care ◽

Hcv Rna ◽

Primary Care Settings ◽

Hcv Screening ◽

The Individual ◽

Point Of Care Assay

Linkage to care presents one obstacle toward eliminating HCV, and the current two-step pathway (anti-HCV, followed by HCV-RNA testing) results in the loss of patients. HCV screening was tested in the primary care setting with the fingerstick Xpert HCV viral load point-of-care assay to analyze the practicability of immediate diagnosis. Anti-HCV (Cobas) and HCV-RNA (Cobas Amplicor version 2.0, only performed if anti-HCV was positive) were analyzed centrally as the gold standard. The Xpert assay was performed by 10 primary care private practices. In total, 622 patients were recruited. Five individuals (0.8%) were anti-HCV positive, and one was HCV-RNA positive. The Xpert test was valid in 546/622 (87.8%) patients. It was negative in 544 and positive in 2 cases, both of whom were anti-HCV negative. The HCV-RNA PCR and the Xpert test were both negative in 4/5 anti-HCV-positive cases, and the individual with HCV-RNA 4.5 × 106 IU/mL was not detected by the Xpert test. Primary care physicians rated the Xpert test practicability as bad, satisfactory, or good in 6%, 13%, and 81%, respectively, though 14/29 (48%) bad test ratings were assigned by a single practice. Despite adequate acceptance, interpretability and diagnostic performance in primary care settings should be further evaluated before its use in HCV screening can be recommended.

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