Hiv hcv and hbv in injecting drug users in europe
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EMCDDA conference. May 2009. HIV, HCV, and HBV in injecting drug users in Europe. Mirjam Kretzschmar Centre for Infectious Disease Control, RIVM, and Julius Center for Health Sciences & Primary Care University Medical Centre Utrecht, The Netherlands.

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Hiv hcv and hbv in injecting drug users in europe

EMCDDA conference

May 2009

HIV, HCV, and HBV in injecting drug users in Europe

Mirjam Kretzschmar

Centre for Infectious Disease Control, RIVM, and

Julius Center for Health Sciences & Primary Care

University Medical Centre Utrecht, The Netherlands


Hiv hcv and hbv in injecting drug users in europe

HIV infections newly diagnosed in injecting drug users, by year of report, by country, cases per million, 1996–2006.

Source: EMCDDA website


Hiv prevalence among injecting drug users studies with national and subnational coverage

HIV prevalence among injecting drug users — studies with national and subnational coverage.

100%

75%

All injecting drug users, 2005 and 2006

Young injecting drug users

(under age 25), 2005 to 2006

Black dots: national

Blue dots: subnational

Source: EMCDDA website


Hiv hcv and hbv in injecting drug users in europe

Estimated HCV antibody prevalence among injecting drug users — studies with national and subnational coverage

100%

100%

Young injecting drug users

(under age 25), 2005 to 2006

All injecting drug users, 2005 and 2006

Source: EMCDDA website


Hiv hcv and hbv in injecting drug users in europe

Prevalence of markers of HBV infection estimated among national and subnational samples of injecting drug users 2005 to 2006, where data are available

100%

16%

Percentage positive for

current infection (HBsAg)

Percentage positive for

ever infected (antiHBc)

Source: EMCDDA website


Questions

Questions

  • How are HIV and HCV prevalence related?

  • And HBV?

  • How do these prevalences depend on risk behaviour, duration of injecting, intervention?

  • What is the impact of harm reduction on incidence and prevalence?

    Use statistical methods and mathematical modelling to get some answers


Project

Project

  • First project: Sept. 2006 – Nov. 2007 tendered by EMCDDA and conducted as a collaboration between EMCDDA and School of Public Health, University of Bielefeld

    • Set up team of modellers to work on analysis of European data

    • Produce 5 draft papers for publication in international journals

    • Resulted in collaboration with epidemiologists (the ‘Study group‘)

  • Second phase: Collaboration with WHO Europe project: ‘Review statistical methods for estimating HIV incidence in countries with concentrated epidemics’

    • Discuss other modelling issues and approaches

    • Continue EMCDDA work, link with WHO interests

  • Background: EMCDDA EU network on drug related infectious diseases (HIV, hepatitis B/C in IDUs: experts, national focal points in 30 countries


Relationships between hiv and hcv prevalence

Relationships between HIV and HCV prevalence

HIV and HCV prevalence data

for 310 regions

from published studies

Thresholds?

Vickerman et al. submitted


Force of infection links incidence and prevalence

Force of infection links incidence and prevalence

  • Force of infection (FOI):

    • risk per time unit for a susceptible person to become infected

    • depends on exposure and therefore on prevalence

    • can be different for different groups of IDU

    • can change during drug use career

λ

B

susceptible

μ


Link between foi and heterogeneity

Link between FOI and heterogeneity

Sutton et al. J Viral Hepatitis 2008

Estimates of force of infections from

seroprevalence studies in different

populations

Frailty function indicates heterogeneity

with respect to exposure


Hiv hcv and hbv in injecting drug users in europe

Force of infection as a function of time since start of injecting:

Exposure duration

  • Caveats:

  • steady state assumption

  • impact of intervention?

Hamata et al; in preparation


Hiv hcv and hbv in injecting drug users in europe

How effective have NEPs been?

Hurley et al Lancet 1997

Amundsen et al Eur J Pub Health 2003

How can we interpret ecological studies?


Decline hiv and hcv incidence in acs 1985 2005

Decline HIV and HCV incidence in ACS 1985-2005

Amsterdam Cohort Studies among drug users

  • Prospective HIV testing

  • Retrospectively tested for HCV antibodies

  • 952 ever injecting DU

    58 HCV infections

    90 HIV infections

30

HCV

0

10

HIV

0

Van den Berg et al. Eur J Epidemiol 2007

1985 - 2004


Is it all really the effect of harm reduction

Is it all really the effect of harm reduction?

Possible other explanation:

Demographic changes in IDU population (e.g., ageing)

Disease related mortality in those groups at highest risk of infections in the first decade of the HIV epidemic might have led to a change in the composition of the IDU population with less risk behaviour and lower transmission rates at the population level over calendar time.

Smit et al, JAIDS 2008


Conclusions

Conclusions

  • Epidemiology of HIV and HCV is closely related, but need to understand better thresholds and transmission dynamics

  • Force of infection links incidence and prevalence, can say something about heterogeneity if we have data about more than on infection

  • The impact of calender time on these relationships is not yet clear, need cohort studies to analyse that

  • We need to disentangle impact of harm reduction from other influences – demographic changes, behaviour changes


Acknowledgements

Acknowledgements

  • Lucas Wiessing

  • Peter Vickerman

  • Ziv Shkedy

  • Emma White

  • Andrew Sutton

  • Viktor Mravcik

  • Cathy Matheï

  • Maria Prins

  • Fernando Vallejo

  • Barbara Suligoi

  • Lillebil Norden

    and all other members of the study group


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