Feasibility of a repetitive prevalence study among the general population

Research Period

1 October 2007 - 30 November 2008


Belgian Science policy



Key Words

prevalence, feasibility, general population


Policymakers need reliable and accurate data about the features and the size of the drug phenomenon in Belgium. This data is necessary to define priorities, to plan efficient interventions, and to evaluate the long-term policy. Belgium is obligated to gather this data to inform the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) about the prevalence of drug use among the Belgian population.

Research Question

Although a lot of studies have been carried out in relation to the prevalence of drug use among young people, the knowledge of the prevalence of drug use among the Belgian population is limited. So far, the prevalence of drugs use within the Belgian population has never been researched.


The objective of this study is a detailed comparison of methods and designs, used in prevalence studies in other countries. This contains the evaluation of the strengths, the restrictions, the preconditions and the costs of former studies. Finally, this study consists of the formulation of concrete recommendations for the implementation of a prevalence study in the future.


This research consists of a cooperation between the Institute for Social Drug Research (ISD) and the 'Centrum voor Longitudinaal en Levensloop Onderzoek' (CELLO). ISD focuses on the intrinsic components, CELLO on the methodological-technical components.

The project contains three parts: 1) a study of the literature, 2) a postal survey of international experts and 3) a profound analysis of the collected data. The research will start with a literature study, which aims at making a meta-analysis of the international guidelines and existing research in Europe. Both the European guidelines and the existing research designs, will be compared with some examples of 'good practice' from abroad. With the literature study, we will set up a postal survey to apply various experts. At the end, we will compare the results from the literature study with those from the postal survey. The final report will also include a cognitive test of the suggested questionnaire items.


We may conclude that a Belgian population survey on drug use is feasible when the possibilities and restrictions of the Belgian context are taken into account. The national policy makers have a choice between three feasible scenarios: a ‘maximal single survey scenario’, a ‘minimal single survey scenario’, and a ‘piggybacking scenario’. Each scenario consists of a questionnaire (in Dutch, French and English), a realistic estimate of the budget (overhead, fieldwork, equipment, operational costs, etc.) and the time required to conduct a Belgian population survey, a detailed description of (the strengths and limitations of) the research design and a thorough explanation of how national policy makers can make data easy available and accessible to interested people.

As cross-national comparability is one of the strengths of population surveys on illicit drug use in Europe, the Belgian population survey on drug use must pursue high compatibility with the European Model Questionnaire (EMQ) and the existing European population surveys. However, as the cognitive test reveals several biases in the EMQ, the Belgian population survey must strike a balance between compatibility with the EMQ (and cross-national comparability with other population surveys in Europe) and the quantity and quality of the survey data. We hope that this feasibility study gives an initial impetus to the dialogue on the implementation of a Belgian population survey on drug use. Population surveys on drug use are an important data source for drafting the objectives of a national drug policy (policy formulation) or for evaluating the existing policy (policy evaluation). The ready availability of this information also plays an important role in sustaining the public debate and in strengthening preventive actions (e.g. prevention campaigns). As Belgium has no information about the drug use among the general population (except for some questions in the HIS), a population survey on drug use may constitute a first attempt at getting a detailed image of drug use among the general population. Only the inclusion of a population survey with more specific questions on illicit drug use will enable Belgium to comply with the international guidelines (e.g. EMQ, WHO) and to improve cross-national comparability. This research study shows that the desirability and feasibility of a Belgian population survey on illicit drug use is beyond discussion.

Valorisation: publications and lectures

Expert seminar: Scenarios for a Belgian population survey on drug use (April 29th 2009, Brussels)

  • DECORTE, T., MORTELMANS, D., TIEBERGHIEN, J. & DE MOOR, S. (2009). Haalbaarheid van een repetitieve prevalentiestudie onder de algemene bevolking. Gent: Academia Press.
  • DECORTE, T., MORTELMANS, D., TIEBERGHIEN J. & DE MOOR, S. (2009). Drug use: an overview of general population survey in Europe. Lisbon: EMCDDA. (electronic version)
  • TIEBERGHIEN, J., DE MOOR, S., DECORTE, T. & MORTELMANS, D. (2008) Meta-analysis of general population surveys in Europe. Paper presented at the Expert meeting 'Prevalence and patterns of drug use among general population'. Lissabon (Portugal), 26-27 juni 2008.
  • DE MOOR S., TIEBERGHIEN J., DECORTE T. & MORTELMANS D. (2008). Pros and cons: single versus piggybacking. Paper presented at the Round table 'General health surveys versus specialised drug surveys'. Lissabon (Portugal), 26-27 juni 2008.