Evaluation of dried blood spot as an alternative specimen for the diagnosis of anti-HCV in resource-limited settings

Evaluation of the diagnostic accuracy of laboratory-based screening for hepatitis C in dried blood spot samples: A systematic review and meta-analysis

The dried blood spot (DBS) is increasingly used for the hepatitis C virus (HCV) screening. Our objective was to perform a meta-analysis of the methodology for HCV screening in DBS samples, particularly in the type of diagnostic assay used. We performed a meta-analysis of all eligible studies published to date (March 2018). The literature search revealed 26 studies: 21 for detection of anti-HCV antibodies and 10 for detection of HCV-RNA. Statistical analyses were performed using Meta-DiSc and STATA (MIDAS module). For detection of HCV antibodies, pooled diagnostic accuracy measures were as follows: sensitivity 96.1%, specificity 99.2%, positive likelihood ratio (PLR) 105, negative likelihood ratio (NLR) 0.04, diagnostic odds ratio (DOR) 2692.9, and summary receiver operating characteristic (SROC) 0.997 ± 0.001. For detection of HCV-RNA, the pooled diagnostic accuracy measures were as follows: sensitivity 97.8%, specificity 99.2%, PLR 44.8, NLR 0.04, DOR 1966.9, and SROC 0.996 ± 0.013. Similar values of pooled diagnostic accuracy measures were found according to the type of anti-HCV antibody detection assay (enzyme-linked immunosorbent assay, rapid diagnostic test, and chemiluminescence assays) and HCV-RNA detection assay (real-time polymerase chain reaction and transcription-mediated amplification). The analysis of external validity showed a high negative predicted value (NPV) for both approaches, but a low positive predicted value (PPV) when prevalence was < 10%, particularly in HCV-RNA tests. Finally, this meta-analysis is subject to limitations, especially publication bias and significant heterogeneity between studies. In conclusion, HCV screening in DBS samples has an outstanding diagnostic performance, with no relevant differences between the techniques used. However, external validity may be limited when the HCV prevalence is low.

Detection of anti-hepatitis C virus and hepatitis C virus RNA in dried blood spot specimens using Whatman No. 1 filter paper

Purpose

Dried blood spot (DBS) specimen simplifies blood collection, processing, storage and shipment and may reduce the cost of testing for hepatitis C virus (HCV) infection. We wanted to see if DBS using a cheap filter paper is reliable alternative to serum for detection of anti-HCV and HCV RNA.

Materials and Methods

At a tertiary care hospital in Northeast India, we collected 91 paired DBS and serum specimens from patients at risk of HCV infection from July 2014 to June 2015. DBS was collected on Whatman No. 1 filter paper. After processing, the specimens were subjected to anti-HCV detection by a third-generation Enzyme-Linked Immunosorbent Assay (ELISA). The reactive DBS and serum specimens were further subjected to HCV RNA detection by polymerase chain reaction. The results were analysed in paired screen-positive study design.

Results

Anti-HCV was detected in 9 (9.9%) DBS specimens and 10 (10.9%) serum specimens. There was statistically significant (P < 0.0001) correlation between the optical density values of DBS and serum specimens (Pearson r = 0.9181, 95% confidence interval: 0.8781-0.9453). HCV RNA was detected in 5/9 (55.6%) reactive DBS and 9/10 (90.0%) reactive serum specimens. There was no correlation between HCV RNA levels in the DBS and the serum specimens. The relative sensitivity rate and the relative false-positive rate of DBS anti-HCV ELISA were 0.89 and 1.00, respectively.

Conclusions

DBS using Whatman No. 1 filter paper is quite reliable as serum for detection of anti-HCV. It can be useful in effective surveillance. However, it is not suitable for confirmation of chronic HCV infection.

Diagnostic accuracy of serological diagnosis of hepatitis C and B using dried blood spot samples (DBS): two systematic reviews and meta-analyses

BACKGROUND

Dried blood spots (DBS) are a convenient tool to enable diagnostic testing for viral diseases due to transport, handling and logistical advantages over conventional venous blood sampling. A better understanding of the performance of serological testing for hepatitis C (HCV) and hepatitis B virus (HBV) from DBS is important to enable more widespread use of this sampling approach in resource limited settings, and to inform the 2017 World Health Organization (WHO) guidance on testing for HBV/HCV.

METHODS

We conducted two systematic reviews and meta-analyses on the diagnostic accuracy of HCV antibody (HCV-Ab) and HBV surface antigen (HBsAg) from DBS samples compared to venous blood samples. MEDLINE, EMBASE, Global Health and Cochrane library were searched for studies that assessed diagnostic accuracy with DBS and agreement between DBS and venous sampling. Heterogeneity of results was assessed and where possible a pooled analysis of sensitivity and specificity was performed using a bivariate analysis with maximum likelihood estimate and 95% confidence intervals (95%CI). We conducted a narrative review on the impact of varying storage conditions or limits of detection in subsets of samples. The QUADAS-2 tool was used to assess risk of bias.

RESULTS

For the diagnostic accuracy of HBsAg from DBS compared to venous blood, 19 studies were included in a quantitative meta-analysis, and 23 in a narrative review. Pooled sensitivity and specificity were 98% (95%CI:95%-99%) and 100% (95%CI:99-100%), respectively. For the diagnostic accuracy of HCV-Ab from DBS, 19 studies were included in a pooled quantitative meta-analysis, and 23 studies were included in a narrative review. Pooled estimates of sensitivity and specificity were 98% (CI95%:95-99) and 99% (CI95%:98-100), respectively. Overall quality of studies and heterogeneity were rated as moderate in both systematic reviews.

CONCLUSION

HCV-Ab and HBsAg testing using DBS compared to venous blood sampling was associated with excellent diagnostic accuracy. However, generalizability is limited as no uniform protocol was applied and most studies did not use fresh samples. Future studies on diagnostic accuracy should include an assessment of impact of environmental conditions common in low resource field settings. Manufacturers also need to formally validate their assays for DBS for use with their commercial assays.

Who to test and how to test for chronic hepatitis C infection - 2016 WHO testing guidance for low- and middle-income countries

Testing and diagnosis of hepatitis C virus (HCV) infection is the gateway for access to both treatment and prevention services, and crucial for an effective hepatitis epidemic response. In contrast to HIV, a systematic approach to hepatitis C testing has been fragmented and limited to a few countries, and there remains a large burden of undiagnosed cases globally. Key challenges in the current hepatitis testing response, include lack of simple, reliable, and low cost diagnostic tests, laboratory capacity, and testing facilities; inadequate data to guide country-specific hepatitis testing approaches and who to test; stigmatization and social marginalization of some groups with or at risk of viral hepatitis; and lack of international or national guidelines on hepatitis testing for resource-limited settings. New tools to support the hepatitis global response include the 2016 Global Hepatitis Health Sector Strategy which include targets for testing and diagnosis, and World Health Organization (WHO) 2016 hepatitis testing guidelines for adults, adolescents, and children in low- and middle-income countries. The testing guidance complements recent published WHO guidance on the prevention, care and treatment of chronic hepatitis C and hepatitis B infection. These testing guidelines outline the public health approach to strengthening and expanding current testing practices for HCV and HBV and address what serological and virological assays to use, and who to test, as well as interventions to promote linkage to prevention and care after testing. They are intended for use across all age groups and populations. See boxes for key recommendations. Future directions and innovations in viral hepatitis testing include use of point-of-care assays for nucleic acid testing (NAT) and core antigen; validation of dried blood spots specimens with different commercial serological and NAT assays; multiplex and polyvalent platforms for integrated testing of HIV, HBV and HCV; and potential for self-testing.