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Archives of Public Health

Volume 73 Supplement 1

Methods in Epidemiology Symposium

Open Access

Health care trajectories and medication consumption of substance users in treatment: linking TDI and IMA databases (Belgium)

  • Karin De Ridder1,
  • Jérôme Antoine1,
  • Lies Gremeaux1,
  • Els Plettinckx1,
  • Peter Blanckaert1 and
  • Jean Tafforeau1
Archives of Public HealthThe official journal of the Belgian Public Health Association201573(Suppl 1):P30

Published: 17 September 2015


As problem substance use has a relative low prevalence and is often socially stigmatised, it is rather difficult to study health care trajectories and medication consumption among substance users. In Belgium, the Treatment Demand Indicator register (TDI) is a major information source for drug epidemiology. However, it should be considered as an incidence register as only new drug-related treatment episodes are registered. Linkage with national compulsory health insurance data (IMA) will create a data source in which longitudinal and case-control studies can be performed.


In the TDI register, every new treatment episode started by a person in a treatment centre for his/her alcohol or illicit drug use is registered. This research project will comprise TDI data (2011-2014) with the client's sociodemographic profile, substance use pattern and treatment information linked to a 10-years period of IMA data (2008-2017). IMA collects the data from the seven Health Insurance Organizations in three databases: (1) population database, (2) reimbursed health care, (3) reimbursed prescribed medicines. A Trusted Third Party (eHealth) is to link the coded version of the unique national identification number (NIN) of both registers. Each TDI case will be matched by sex, age and municipality with four controls who have no administrative registrations of drug treatment in the TDI and IMA registers. The research project has been approved by the Privacy Commission (SCSZG/15/033) and the linkage will be executed from autumn 2015.


The TDI register (2011-2014) contains 50,291 persons and 69% (N=34,628) clients with a unique NIN are eligible for linkage. Among them, 75% were male. In 41% of the registered cases, the primary substance was alcohol, followed by cannabis (21%), opiates (17%), cocaine (9%) and stimulants other than cocaine (7%).


A linkage of TDI-IMA will result in the first large-scaled longitudinal database in the Belgian drug epidemiology.

Authors’ Affiliations

Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium


© De Ridder et al. 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.


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