Evaluación de la precisión diagnóstica del sistema Cobas 6800 para la detección de los niveles de viremia del virus de la hepatitis C a partir de muestras de gotas de sangre seca en papel de filtro

Dried Blood Spots-A Platform for Therapeutic Drug Monitoring (TDM) and Drug/Disease Response Monitoring (DRM)

This review provides an overview on the current applications of dried blood spots (DBS) as matrices for therapeutic drug (TDM) and drug or disease response monitoring (DRM). Compared with conventional methods using plasma/serum, DBS offers several advantages, including minimally invasiveness, a small blood volume requirement, reduced biohazardous risk, and improved sample stability. Numerous assays utilising DBS for TDM have been reported in the literature over the past decade, covering a wide range of therapeutic drugs. Several factors can affect the accuracy and reliability of the DBS sampling method, including haematocrit (HCT), blood volume, sampling paper and chromatographic effects. It is crucial to evaluate the correlation between DBS concentrations and conventional plasma/serum concentrations, as the latter has traditionally been used for clinical decision. The feasibility of using DBS sampling method as an option for home-based TDM is also discussed. Furthermore, DBS has also been used as a matrix for monitoring the drug or disease responses (DRM) through various approaches such as genotyping, viral load measurement, assessment of inflammatory factors, and more recently, metabolic profiling. Although this research is still in the development stage, advancements in technology are expected to lead to the identification of surrogate biomarkers for drug treatment in DBS and a better understanding of the correlation between DBS drug levels and drug responses. This will make DBS a valuable matrix for TDM and DRM, facilitating the achievement of pharmacokinetic and pharmacodynamic correlations and enabling personalised therapy.

Hepatitis C diagnosis slowdown in high-prevalence groups and using decentralised diagnostic strategies during the COVID-19 pandemic

INTRODUCTION

The COVID-19 pandemic has had a major impact on hepatitis C virus (HCV) diagnosis by hindering the path to elimination, although probably in an uneven manner depending on the risk group and diagnostic strategy.

METHODS

We recorded the requests of antibodies/RNA by venipuncture at the hospital and primary care centres (centralised), as well as the requests via venipuncture or dried blood spot test at prison and drug treatment centres referred for central processing (integrated decentralised), for one year before and after the onset of the COVID-19 health alarm.

RESULTS

A total of 20,600 tests (51% male, 47.9±15.8 years) were recorded. Among them, 96.5% of the cases came from centralised and 3.5% from decentralised settings, with an active infection rate of 0.2% and 2.3% (p<0.001), respectively. There was a 31.3% decrease in the number of requests during the pandemic compared to the pre-pandemic period, which was more pronounced in decentralised diagnosis than centralised (60 vs. 30%, p<0.001). In addition, there was a 31.5% decline in screening and an 18.2% decrease in the diagnosis of new cases of active infection, showing a statistically significant decrease in decentralised compared to centralised diagnosis.

CONCLUSIONS

During the COVID-19 pandemic, a decline in HCV diagnostic effort has been observed, especially in decentralised strategies with a higher prevalence of infection. Our results suggest a diagnostic delay that will prevent Spain from reaching the elimination target in 2023, and therefore the reactivation of strategies particularly targeting the priority groups is urgently required.

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

The use of dried blood spot (DBS) samples can facilitate the implementation of reflex testing by circumventing the need for centrifugation and freezing of venous blood samples. This systematic review assessed the accuracy of using DBS samples to diagnose chronic hepatitis C virus (HCV) infection. A comprehensive search was undertaken to identify articles published up to July 2020 evaluating the diagnostic accuracy of anti-HCV, HCV-RNA and HCV core antigen tests using DBS. Screening, data extraction, quality appraisal and Grading of Recommendations, Assessment, Development and Evaluations certainty of the evidence assessment were performed independently by two reviewers. Meta-analysis, meta-regression and sensitivity analyses were conducted. The evidence demonstrates that laboratory-based anti-HCV and HCV-RNA tests using DBS samples have high diagnostic accuracy. All comparisons were between DBS and venous samples. For the detection of anti-HCV, sensitivity was 95% (95% CI: 92%-97%) and specificity was 99% ([95% CI: 98%-99%]; n = 25; I²  = 81%; moderate certainty). For the detection of HCV-RNA, the sensitivity was 95% (95% CI: 93%-97%) and specificity was 97% ([95% CI: 94%-98%]; n = 20; I²  = 52%; moderate certainty). The sensitivity of HCV core antigen tests was 86% (95% CI: 79%-91%) and specificity was 98% ([95% CI: 94%-99%]; n = 5; I²  = 37%; low certainty) compared with HCV-RNA (the gold standard for detecting chronic HCV). DBS samples could facilitate diagnosis of chronic HCV infection as the necessary sequential tests (anti-HCV and then HCV-RNA or HCV core antigen) can be undertaken using the same blood sample. This could reduce loss of patient follow-up and support international efforts towards HCV elimination in both high and low prevalence settings.

Telemedicine and decentralized hepatitis C treatment as a strategy to enhance retention in care among people attending drug treatment centres

BACKGROUND

People attending drug treatment centres have a high burden of hepatitis C virus (HCV) and face barriers to diagnosis and treatment. Dried blood spot (DBS) testing has been proposed to simplify diagnosis, but many patients remain untreated. In this retrospective study, we evaluated the reasons for non-retention in care in an intervention using on-site DBS testing and the effect of telemedicine and decentralized care compared to standard of care among people attending drug treatment centres who were lost to follow-up.

METHODS

In a first phase, retention in care, adherence to treatment, and predictive factors in the DBS testing program of patients in drug treatment centres were analyzed and compared to a cohort of patients treated at the hospital outpatient clinic. Subsequently, in a second phase we evaluated in patients lost to follow-up from drug treatment centres the efficacy of one-step testing and telemedicine linked to a decentralized dispensation of HCV treatment or standard of care.

RESULTS

Among 512 patients attending drug treatment centres, 467 (91.2%) agreed to be tested and 53.4% (237 patients/444 valid tests) tested positive (46 ± 9 years, 87.3% male) for HCV antibodies. After excluding patients negative for RNA or under surveillance, 178 patients were scheduled to meet with a specialist. Overall, 44 patients did not attend and 25 did not complete the pre-treatment evaluation. The only factor associated with retention in care was patient's knowledge of HCV infection. Treated patients attending drug treatment centres (n = 68) compared to the hospital outpatient clinic cohort (n = 135) had lower rates of treatment adherence. Among the patients who attended drug treatment centres that were lost to follow-up (n = 69), the proportion of patients who completed the program was significantly higher among those assisted by telemedicine than by standard of care (62.5% vs. 24.3%, p = 0.002).

CONCLUSION

Although there was a high participation rate in a DBS testing program in drug treatment centres, non-retention in care is a challenge. Importantly, telemedicine linked to a decentralized dispensation of HCV treatment re-engages patients and may be effective for HCV microelimination.

Evaluation of the Aptima HCV Quant Dx Assay for Hepatitis C Virus RNA Detection from Fingerstick Capillary Dried Blood Spot and Venepuncture-Collected Samples

BACKGROUND

Simplified diagnostic strategies are needed increase hepatitis C virus (HCV) testing to determine active infection and link people into treatment. Collection methods such as dried blood spots (DBS) have advantages over standard phlebotomy, especially within marginalized populations.

METHODS

We evaluated the diagnostic performance of the Aptima HCV Quant assay for the quantification and detection of HCV RNA from paired DBS and venepuncture samples. Specimens were collected from participants enrolled in an Australian observational study. We compared HCV RNA detection from DBS against venepuncture samples (gold standard).

RESULTS

One hundred sixty-four participants had paired samples and HCV RNA was detected in 45 (27% [95% confidence interval, 21%-35%]) by the Aptima assay in venepuncture samples. Sensitivity of the Aptima assay for HCV RNA quantification from DBS (≥10 IU/mL in plasma) was 100% and specificity was 100%. Sensitivity for HCV RNA detection from DBS was 95.6% and specificity was 94.1%. A small bias in plasma over DBS was observed with good agreement (R2 = 0.96).

CONCLUSIONS

The Aptima HCV Quant assay detects active infection from DBS samples with acceptable diagnostic performance and is clinically comparable to plasma. These data will strengthen the case for the registration of a DBS kit insert claim, enabling future clinical utility.