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Health care trajectories and medication consumption of substance users in treatment :
linking TDI and IMA databases (Belgium)De Ridder Karin, Antoine Jérôme, Gremeaux Lies, Plettinckx Els, Blanckaert Peter, Tafforeau Jean.
WIV-ISP | Rue Juliette Wytsmanstraat 14 | 1050 Brussels | BelgiumT +32 2 642 57 61 | e-mail: [email protected] | site web: https://drugs.wiv-isp.be
Background• Problem substance use has a relative low prevalence and is often socially
stigmatised: health care trajectories and medication consumption among substance users are notoriously difficult to study
• The Belgian Treatment Demand Indicator register (TDI): • An European standardized tool collecting information on substance users
getting in contact with health professionals (tdi.wiv-isp.be) • Linkage with the health care and prescription register of the Belgian national
compulsory health insurance (IMA)(www.ima-aim.be) to create a data source in which longitudinal and case-control research on medication consumption and health care trajectories among substance users in treatment can be performed
MethodsTDI register:• Registration of every new treatment episode started in a treatment centre for
alcohol or illicit drug abuse • Limitation: only new treatment episodes for substance use are registered
and as such, it should be considered as an incidence register. On its own, it can’t serve as source for longitudinal studies on the individual level nor case-control studies.
• Extraction of records from centres specialized in treatment of drug addiction, some centres of mental health and general or psychiatric hospitals from 2011 until 2014
• Data on the client's socio-demographic profile, substance use pattern and treatment information
IMA databases• Data from seven Belgian Health Insurance Organizations in three national
databases: • (1) population database with socio-demographic data, • (2) health care database with administrative information on reimbursed
health care provision • (3) Farmanet database with data on reimbursed prescriptions
• Limitation: difficult to identify patients with substance use problem• Extraction of selected data related to socio-demography, health care and
prescriptions from 2008 until 2017
2011 TDI 2014
2008 IMA 2017
Time periods of data used in linkage:
Results• 69% (N=34,628) of the TDI records have a unique NIN and are eligible for
linkage with the three IMA databases (table 1)• Among them, 75% were male (figure 1), mean age was 36.5 years and 94%
were Belgian citizens• Besides the 41% in treatment for primary substance “alcohol”, 21% of the clients
reported to be in treatment for cannabis, followed by opiates (17%), cocaine (9%) and stimulants other than cocaine (7%) (figure 2)
• In 46% of the cases, the clients were registered in an outpatient treatment program, while 54% were in inpatient health care
Identification typeYear of treatment start2011 2012 2013 2014 Total
National identification number (NIN)
5,510(77%)
7,657(75%)
10,059(70%)
11,402(61%)
34,628 (69%)
Other non unique identification type
1,668 2,575 4,332 7,088 15,663 (31%)
Total 7,178 10,232 1,4391 18,490 50,291 (100%)
Table 1 : Number of patients (first treatment episode registered by patient) in the TDI database (Year of treatment start and identification type are indicated)
Figure 1 : Proportion of TDI patients eligible for linkage by age categories and sex
Figure 2: Proportion of TDI patients eligible for linkage by primary substance used
Conclusions• A linkage of TDI and IMA databases will result in the first large-scaled
longitudinal database in the Belgian drug epidemiology• Covers a 10-years period and enables a comparison with a matched control
group• Individual and treatment centres characteristics can be taken into account • First crucial practical steps:
• Recoding the project ID code used in TDI back to the NIN• Evaluate the linkage rate between TDI and IMA registers
Linkage• Both registers will be linked by a coded version of the patient’s unique
national identification number (NIN). In the TDI register, the use of this NIN is not mandatory, so a selection of records has to be made
• A Trusted Third Party (eHealth) is to decode, link and recode the NIN in order to link both registers
Case-control matching (1:4)• Aim: comparison of medical consumption of persons in drug treatment
with persons who did not enter into drug treatment• Each TDI case will be matched by sex, age and municipality with four
control persons from the IMA population database who have no administrative registrations of treatment for substance addiction in the IMA registers and TDI register
Privacy commission• Approved by the Privacy Commission (SCSZG/15/033) Progression• The linkage will be executed from autumn 2015 with a yearly update with
IMA data, up to and including the administrative registration year 2017
