Dried blood spots for HCV measurement among injecting drug users

Dried blood spots for HCV measurement among injecting drug users

A study in the latest issue of the Journal of Viral Hepatitis measures hepatitis C infections among a community recruited sample of injecting drug users, using dried blood spots.

Monitoring hepatitis C virus (HCV) infection among injecting drug users in the community is complicated by difficulties in obtaining biological specimens and biases in recruitment and follow-up.

Dr Vivian Hope and colleagues from the United Kingdom examined the utility of dried blood spot specimens from injecting drug users recruited using respondent-driven sampling.

Active injecting drug users underwent a computer-assisted interview and provided a dried blood spot sample, tested for HCV antibody (anti-HCV) and HCV-RNA.

The researchers estimated HCV incidence from the proportion of anti-HCV-negative subjects found HCV-RNA-positive and estimates of the duration of this state.

Results were adjusted according to injecting drug users dried blood spot derived sample weights.
14 had homology of more than 99%
Journal of Viral Hepatitis

HCV-RNA testing was performed on 288 dried blood spot samples.

The research team found that 173 were anti-HCV-positive, of which 42% were RNA-negative indicating cleared infection.

Among the 115 anti-HCV-negatives, 14 were RNA-positive suggesting an incidence of 38–47 per 100 person years.

The team observed that incident infections were younger than anti-HCV-negative and prevalent infections, at 25 vs. 29 and 34 years, respectively.

The research team noted that incidence was highest among individuals with poor needle exchange coverage.

The researchers genotyped 114 patients, of which 14 had homology of more than 99%, including 10 incident infections.

Public health surveillance of HCV among injecting drug users could be enhanced through the collection of dried blood spot samples with appropriate recruitment approaches.

Dr Hope's team concluded, "Dried blood spot allow differentiation between individuals with cleared infections, ongoing infection and those recently infected."

"They also enable virus characterization at genotype and nucleotide level."

"This would allow surveillance to inform development of harm reduction interventions, and the international evidence base for these."

J Vir Hep 2011: 18(4): 262–70
07 April 2011
http://www.gastrohep.com/news/news.asp?id=107970