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Open Access Research article

A multi-state model to estimate incidence of heroin use

Albert Sánchez-Niubò12, Odd O Aalen3, Antònia Domingo-Salvany12*, Ellen J Amundsen4, Josep Fortiana5 and Kjetil Røysland3

Author Affiliations

1 Drug Abuse Epidemiology Research Group, IMIM- Institut de Recerca Hospital del Mar, Doctor Aiguader 88, E-08003, Barcelona, Spain

2 CIBER in Epidemiology and Public Health, CIBERESP, Doctor Aiguader 88, E-08003, Barcelona, Spain

3 Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, P.O.Box 1122 Blindern, N-0317, Oslo, Norway

4 Norwegian Institute for Alcohol and Drug Research, SIRUS, P.O. box 565 Sentrum, NO-0105, Oslo, Norway

5 Department of Probability, Logic and Statistics, University of Barcelona, Gran Via de les Corts Catalanes 585, E-08007, Barcelona, Spain

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BMC Medical Research Methodology 2013, 13:4  doi:10.1186/1471-2288-13-4

Published: 14 January 2013

Abstract

Background

Existing incidence estimates of heroin use are usually based on one information source. This study aims to incorporate more sources to estimate heroin use incidence trends in Spain between 1971 and 2005.

Methods

A multi-state model was constructed, whereby the initial state “heroin consumer” is followed by transition to either “admitted to first treatment” or to “left heroin use” (i.e. permanent cessation or death). Heroin use incidence and probabilities of entering first treatment ever were estimated following a back-calculation approach.

Results

The highest heroin use incidence rates in Spain, around 1.5 per 1,000 inhabitants aged 10–44, occurred between 1985 and 1990; subdividing by route of administration reveals higher incidences of injection between 1980 and 1985 (a mean of 0.62 per 1.000) and a peak for non-injectors in 1990 (0.867 per 1,000).

Conclusions

A simple conceptual model for heroin users’ trajectories related to treatment admission, provided a broader view of the historical trend of heroin use incidence in Spain.

Keywords:
Back-calculation; Epidemiology; Heroin; Incidence; Multi-state model