1. Modelling hepatitis C infection among injecting
drug users in Oslo
Ioana Bradeanu, Mirjam Kretzschmar1 and Olav Dalgard2
1University Medical Centre Utrecht, The Netherlands and National Institute for Public Health and the Environment, Bilthoven, The Netherlands
2Department of Infectious Diseases, Akershus University Hospital, 1478 Lørenskog, Norway
Background
Hepatitis C (HCV) infection is a serious health problem with
the potential to induce cirrhosis and endstage liver disease in
a significant number of those infected [1]. HCV treatment
reduses an individual’s risk of developing chronic liver
disease, cirrhosis and hepatocellular carcinoma and
improves quality of life [2]. Treating HCV in people who
currently inject drugs also has a broader public health
benefit. It has been suggested that only a small proportion of
people who currently inject drugs need to be treated to
significantly reduce HCV infection prevalence among
injecting drug users over 20 years [3].
References
[1] Dalgard O, Jeansson S, Skaug K, Raknerud N, Bell H. Hepatitis C in the General Adult Population of Oslo:
Prevalence and Clinical Spectrum. Scand J Gastroenterol 2003;38:864–870.
[2] Shepard CW, Finelli l, Alter M J. Global epidemiology of hepatitis C virus infection. Lancet Infect Dis 2005;
5; 558-567
[3] Natasha K. Martin, Peter Vickerman, and Matthew Hickman, Mathematical modelling of hepatitis C
treatment for injecting drug users. Journal of Theoretical Biology 274 (2011) 58–66
[4] Martin N, Vickerman P, Foster G et al. Can antiviral therapy for Hepatitis C reduce the prevalence among
injecting drug user populations? A modelling analysis of its prevention utility. J. Hepatol 2011; 54: 1137-1144
Aims
To develop a mathematical model to project the potential
impact of hepatitis C virus (HCV) treatment on HCV infection
prevalence among injecting drug users in Oslo.
Design
We are using Norwegian estimates of the number of people
who are currently active injecting drug users, average duration
of injecting, chronic HCV infection prevalence among people
who inject drugs, anual mortality, and annual HCV treatment
rate.
Outcome measure
Prevalence of chronic HCV infection among people who are
currently active injecting drug users.
Mathematical model
We consider a mathematical model to depict HCV in the
population of IDU [4]. The IDUs population are separated
into: the susceptible group S, individuals that are injecting but
not infected; the acutely infected group A, individuals that
have contracted HCV but have yet to pass to the chronic stage
of the disease; the chronically infected group, C; the HCV
treatment group T; and individuals who have recovered from
HCV either spontaneously or through HCV treatment R.
Given the short period of acute infection, and that this
frequently goes undetected, only chronically infected
individuals were assumed to enrol in HCV treatment.
Results
We investigate the impact on HCV prevalence of increasing levels
of HCV treatment.
The effect of the treatment rate of acutely infected and chronically
infected users in the endemic steady state.
The steady state value of the mathematical model.
Baseline chronic
prevalence, 50%.
Baseline treatment
rate 1/1000 IDU
annually
Estimated reduction in chronic HCV infection prevalence
among IDU over time through antiviral treatment at different rates
Estimated effect of treatment rate on reduction
in chronic HCV infection prevalence among IDU at 15 and 30 years
Assuming full treatment rate.
Baseline chronic prevalence,
50%.
Baseline treatment rate
1/1000 IDU
annually.