Background and methods

The World Health Organization has set a goal to eliminate hepatitis C virus (HCV) as a global public health threat by 2030. Targets include reducing new HCV infections by 80%, the number of HCV deaths by 65%, and increasing HCV diagnoses from 20 to 90% and eligible people receiving HCV treatment from <5 to 80%.1 Unsafe injecting drug use is the main route of HCV transmission in developed countries.2 Consequently, people who inject drugs (PWID) in the general and prison population represent a priority population for HCV elimination, given the high prevalence and incidence in this group. However, the prevalence of HCV infection among PWID in Ireland remains poorly understood. A recent study aimed to map key previous findings and identify gaps in the literature (published and unpublished) on HCV infection in Irish PWID and prisoners.3 

In this research, published in the BMC journal Infectious Diseases, a scoping review was carried out, guided by the methodological framework set out by Levac and colleagues (based on previous work by Arksey and O’Malley).4,5 

Results

Two 2014 studies identified from the grey literature reported on HCV infection in PWID attending methadone maintenance therapy (MMT) in drug clinics outside of Dublin and reported an anti-HCV prevalence of 24% (Horan A (2014): Chart audit of HCV screening measuring the effect of chart labelling, unpublished).6 A published 2017 study reported an anti-HCV prevalence of 63.6% among PWID attending MMT at a north Dublin inner-city treatment centre.7 

Two large HCV screening audits in 2016 reported an anti-HCV prevalence of almost 80% and a chronic HCV prevalence of 65% among PWID attending MMT at 23 drug treatment clinics in Dublin (Burke M (2016): Audit of HCV screening using retrospective patient records, unpublished). The most recent prevalence study in PWID attending opioid substitution therapy in general practice in Ireland reported an anti-HCV prevalence of 77.2%.8 

With regard to the prison population, a 2014 study conducted in 13 of the 15 prisons in the Republic of Ireland reported an anti-HCV prevalence of 13% (95% CI: 10.9–15.2%) among the general prison population, increasing to 41.5% in prisoners with a history of injecting drug use and 54% in those with a history of injecting heroin.9 Another prison study from 2014 (single site) reported an HCV prevalence of 37% among prisoners on MMT.10 

Conclusions

The authors noted that only two studies reported on HCV prevalence in PWID outside of Dublin and both were from secondary urban centres. In addition, the majority of the prevalence studies were over a decade old and only reported on anti-HCV prevalence and not on HCV RNA prevalence, which limits their usefulness at estimating the levels of chronic untreated infection and reinfection. Finally, the most recent epidemiological studies included in the review were mostly chart review audits, which limit their usefulness in informing policy and strategy.

1 World Health Organization (WHO) (2017) Global hepatitis report 2017. Geneva: WHO. https://www.drugsandalcohol.ie/27177/

2 Nelson P, Mathers B, Cowie B, Hagan H, Des Jarlais D, Horyniak D, et al. (2011) Global epidemiology of hepatitis B and hepatitis C in people who inject drugs: results of systematic reviews. Lancet, 378(9791): 571–83. https://www.drugsandalcohol.ie/15845/

3 Crowley D, Murtagh R, Cullen W, Lambert JS, McHugh T and Van Hout MC (2019) Hepatitis C virus infection in Irish drug users and prisoners – a scoping review. BMC Infect Dis, 19(1): 702. https://www.drugsandalcohol.ie/31395/

4 Levac D, Colquhoun H and O’Brien KK (2010) Scoping studies: advancing the methodology. Implement Sci, 5: 69.

5 Arksey H and O’Malley L (2005) Scoping studies: towards a methodological framework. Int J Soc Res Methodol, 8: 19–32.

6 Ryan H and Ryan S (2014) Increasing incidence of hepatitis C among intravenous drug users in HSE Mid-West. NIHS Res Bull, 7(1): 32. https://www.drugsandalcohol.ie/22639/

7 Keegan D, Crowley D, Laird E and Van Hout MC (2017) Prevalence and risk factors for hepatitis C viral infection amongst a cohort of Irish drug users attending a drug treatment centre for agonist opioid treatment (AOT). Heroin Addict Relat Clin Probl, 19(1): 45–54. http://www.drugsandalcohol.ie/25815/

8 Murtagh R, Swan D, O’Connor E, McCombe G, Lambert JS, Avramovic G, et al. (2018) Hepatitis C prevalence and management among patients receiving opioid substitution treatment in general practice in Ireland: baseline data from a feasibility study. Interact J Med Res, 7(2): e10313. https://www.drugsandalcohol.ie/30874/

9 Drummond A, Codd M, Donnelly N, McCausland D, Mehegan J, Daly L, et al. (2014) Study on the prevalence of drug use, including intravenous drug use, and blood-borne viruses among the Irish prisoner population. Dublin: National Advisory Committee on Drugs and Alcohol. https://www.drugsandalcohol.ie/21750/

10      Galander T, Rosalim J, Betts-Symonds G and Scully M (2014) A survey of patients on methadone programmes in Wheatfield Prison, Dublin, Ireland. Heroin Addict Relat Clin Probl, 16(2): 17–22. https://www.drugsandalcohol.ie/23736/