Abstract

Background: The hidden nature of the use of opioids, amphetamines, cocaine, and cannabis (the most commonly used and studied illicit drugs) precludes the accurate estimation of how many people use them and further important aspects of the use. Among the many aspects of drug use, the permanence times in specific drug using states related to the lifestyles of the various sub populations of users are of interest, per se, as essential components of estimates relating prevalence and incidence of drug use and for evaluating policies.

Methods: Several administrative databases and surveys collected in Italy and in different EU countries concerning different sub-populations of drug users were analysed to estimate the permanence time in a specific drug using state and the stages of a typical drug-using career.

Results: Cannabis is mostly the first illegal substance used. The age at onset corresponds to the very beginning of adolescence and various sources indicate that this onset happens earlier for men than for women. For problematic drug users, the switch from cannabis to heavy drugs happens within a rather narrow period of time, within 5-6 years from the first use of cannabis, along with the first episode of drug dealing. The latency period distribution estimated from different data sources is quite stable, with men presenting longer latency periods than women.

Conclusions: The comparative analysis of several data sources allowed a more complete overview of the different subpopulations on the drug scene and provides interesting data to understand and to estimate parameters for dynamic models of drug use.

Keywords: Dynamic models, evaluating interventions, inter-event time, length of stay time, problematic drug use, survey.